Higher-order functions: Difference between revisions
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m (→{{header|Joy}}) |
Thundergnat (talk | contribs) m (syntax highlighting fixup automation) |
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{{trans|Python}} |
{{trans|Python}} |
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< |
<syntaxhighlight lang="11l">F first(function) |
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R function() |
R function() |
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V result = first(second) |
V result = first(second) |
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print(result)</ |
print(result)</syntaxhighlight> |
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{{out}} |
{{out}} |
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Code is called using the following macro, e.g. <code>PrintOutput #$FF,foo</code>. The printing routine is left unimplemented. |
Code is called using the following macro, e.g. <code>PrintOutput #$FF,foo</code>. The printing routine is left unimplemented. |
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< |
<syntaxhighlight lang="6502asm">macro PrintOutput,input,addr |
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; input: desired function's input |
; input: desired function's input |
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; addr: function you wish to call |
; addr: function you wish to call |
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Line 38: | Line 38: | ||
LDA \input |
LDA \input |
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JSR doPrintOutput |
JSR doPrintOutput |
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endm</ |
endm</syntaxhighlight> |
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< |
<syntaxhighlight lang="6502asm">PrintOutput: |
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; prints the output of the function "foo" to the screen. |
; prints the output of the function "foo" to the screen. |
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; input: |
; input: |
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Line 62: | Line 62: | ||
JSR PrintAccumulator |
JSR PrintAccumulator |
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rts</ |
rts</syntaxhighlight> |
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=={{header|68000 Assembly}}== |
=={{header|68000 Assembly}}== |
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This trivial example shows a simple return spoof. |
This trivial example shows a simple return spoof. |
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< |
<syntaxhighlight lang="68000devpac">LEA foo,A0 |
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JSR bar |
JSR bar |
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Line 75: | Line 75: | ||
foo: |
foo: |
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RTS ;do nothing and return. This rts retuns execution just after "JSR bar" but before "JMP *".</ |
RTS ;do nothing and return. This rts retuns execution just after "JSR bar" but before "JMP *".</syntaxhighlight> |
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=={{header|8th}}== |
=={{header|8th}}== |
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< |
<syntaxhighlight lang="forth"> |
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: pass-me |
: pass-me |
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"I was passed\n" . ; |
"I was passed\n" . ; |
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Line 86: | Line 86: | ||
\ pass 'pass-me' to 'passer' |
\ pass 'pass-me' to 'passer' |
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' pass-me passer |
' pass-me passer |
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</syntaxhighlight> |
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</lang> |
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{{out}} |
{{out}} |
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I was passed |
I was passed |
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=={{header|ActionScript}}== |
=={{header|ActionScript}}== |
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< |
<syntaxhighlight lang="actionscript">package { |
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public class MyClass { |
public class MyClass { |
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Line 109: | Line 109: | ||
} |
} |
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} |
} |
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}</ |
}</syntaxhighlight> |
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=={{header|Ada}}== |
=={{header|Ada}}== |
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===Simple Example=== |
===Simple Example=== |
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< |
<syntaxhighlight lang="ada">with Ada.Text_Io; use Ada.Text_Io; |
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procedure Subprogram_As_Argument is |
procedure Subprogram_As_Argument is |
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Line 129: | Line 129: | ||
begin |
begin |
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First(Second'Access); |
First(Second'Access); |
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end Subprogram_As_Argument;</ |
end Subprogram_As_Argument;</syntaxhighlight> |
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===Complex Example=== |
===Complex Example=== |
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< |
<syntaxhighlight lang="ada">with Ada.Text_Io; use Ada.Text_Io; |
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procedure Subprogram_As_Argument_2 is |
procedure Subprogram_As_Argument_2 is |
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Line 182: | Line 182: | ||
Int_Ptr := Complex_Func(F_Ptr, 3); |
Int_Ptr := Complex_Func(F_Ptr, 3); |
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Put_Line(Integer'Image(Int_Ptr.All)); |
Put_Line(Integer'Image(Int_Ptr.All)); |
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end Subprogram_As_Argument_2;</ |
end Subprogram_As_Argument_2;</syntaxhighlight> |
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=={{header|Aime}}== |
=={{header|Aime}}== |
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< |
<syntaxhighlight lang="aime">integer |
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average(integer p, integer q) |
average(integer p, integer q) |
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{ |
{ |
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Line 209: | Line 209: | ||
return 0; |
return 0; |
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}</ |
}</syntaxhighlight> |
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=={{header|ALGOL 68}}== |
=={{header|ALGOL 68}}== |
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{{works with|ALGOL 68G|Any - tested with release [http://sourceforge.net/projects/algol68/files/algol68g/algol68g-1.18.0/algol68g-1.18.0-9h.tiny.el5.centos.fc11.i386.rpm/download 1.18.0-9h.tiny]}} |
{{works with|ALGOL 68G|Any - tested with release [http://sourceforge.net/projects/algol68/files/algol68g/algol68g-1.18.0/algol68g-1.18.0-9h.tiny.el5.centos.fc11.i386.rpm/download 1.18.0-9h.tiny]}} |
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{{wont work with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release [http://sourceforge.net/projects/algol68/files/algol68toc/algol68toc-1.8.8d/algol68toc-1.8-8d.fc9.i386.rpm/download 1.8-8d] - due to extensive use of FORMATted transput}} |
{{wont work with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release [http://sourceforge.net/projects/algol68/files/algol68toc/algol68toc-1.8.8d/algol68toc-1.8-8d.fc9.i386.rpm/download 1.8-8d] - due to extensive use of FORMATted transput}} |
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< |
<syntaxhighlight lang="algol68">PROC first = (PROC(LONG REAL)LONG REAL f) LONG REAL: |
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( |
( |
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f(1) + 2 |
f(1) + 2 |
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Line 228: | Line 228: | ||
main: ( |
main: ( |
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printf(($xg(5,2)l$,first(second))) |
printf(($xg(5,2)l$,first(second))) |
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)</ |
)</syntaxhighlight> |
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Output: |
Output: |
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<pre> |
<pre> |
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Line 236: | Line 236: | ||
=={{header|AmigaE}}== |
=={{header|AmigaE}}== |
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The <tt>{}</tt> takes the pointer to an object (code/functions, variables and so on); Amiga E does not distinguish nor check anything, so it is up to the programmer to use the pointer properly. For this reason, a warning is always raised when a ''variable'' (<tt>func</tt>, holding a pointer to a real function in our case) is used like a function. |
The <tt>{}</tt> takes the pointer to an object (code/functions, variables and so on); Amiga E does not distinguish nor check anything, so it is up to the programmer to use the pointer properly. For this reason, a warning is always raised when a ''variable'' (<tt>func</tt>, holding a pointer to a real function in our case) is used like a function. |
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< |
<syntaxhighlight lang="amigae">PROC compute(func, val) |
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DEF s[10] : STRING |
DEF s[10] : STRING |
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WriteF('\s\n', RealF(s,func(val),4)) |
WriteF('\s\n', RealF(s,func(val),4)) |
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compute({sin_wrap}, 0.0) |
compute({sin_wrap}, 0.0) |
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compute({cos_wrap}, 3.1415) |
compute({cos_wrap}, 3.1415) |
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ENDPROC</ |
ENDPROC</syntaxhighlight> |
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=={{header|AntLang}}== |
=={{header|AntLang}}== |
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< |
<syntaxhighlight lang="antlang">twice:{x[x[y]]} |
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echo twice "Hello!"</ |
echo twice "Hello!"</syntaxhighlight> |
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=={{header|AppleScript}}== |
=={{header|AppleScript}}== |
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< |
<syntaxhighlight lang="applescript">-- This handler takes a script object (singer) |
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-- with another handler (call). |
-- with another handler (call). |
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on sing about topic by singer |
on sing about topic by singer |
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Line 278: | Line 278: | ||
end script |
end script |
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end hire |
end hire |
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sing about "closures" by (hire for "Pipe Organ")</ |
sing about "closures" by (hire for "Pipe Organ")</syntaxhighlight> |
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As we can see above, AppleScript functions (referred to as 'handlers' in Apple's documentation) are not, in themselves, first class objects. They can only be applied within other functions, when passed as arguments, if wrapped in Script objects. If we abstract out this lifting of functions into objects by writing an '''mReturn''' or '''mInject''' function, we can then use it to write some higher-order functions which directly accept unadorned AppleScript handlers as arguments. |
As we can see above, AppleScript functions (referred to as 'handlers' in Apple's documentation) are not, in themselves, first class objects. They can only be applied within other functions, when passed as arguments, if wrapped in Script objects. If we abstract out this lifting of functions into objects by writing an '''mReturn''' or '''mInject''' function, we can then use it to write some higher-order functions which directly accept unadorned AppleScript handlers as arguments. |
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We could, for example, write '''map''', '''fold/reduce''' and '''filter''' functions for AppleScript as follows: |
We could, for example, write '''map''', '''fold/reduce''' and '''filter''' functions for AppleScript as follows: |
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< |
<syntaxhighlight lang="applescript">on run |
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-- PASSING FUNCTIONS AS ARGUMENTS TO |
-- PASSING FUNCTIONS AS ARGUMENTS TO |
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-- MAP, FOLD/REDUCE, AND FILTER, ACROSS A LIST |
-- MAP, FOLD/REDUCE, AND FILTER, ACROSS A LIST |
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on isEven(x) |
on isEven(x) |
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x mod 2 = 0 |
x mod 2 = 0 |
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end isEven</ |
end isEven</syntaxhighlight> |
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{{Out}} |
{{Out}} |
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< |
<syntaxhighlight lang="applescript">{{0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20}, |
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{0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100}, |
{0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100}, |
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{true, false, true, false, true, false, true, false, true, false, true}}</ |
{true, false, true, false, true, false, true, false, true, false, true}}</syntaxhighlight> |
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===Alternative description=== |
===Alternative description=== |
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In plain English, one handler can be passed as a parameter to another either in a script object … |
In plain English, one handler can be passed as a parameter to another either in a script object … |
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< |
<syntaxhighlight lang="applescript">script aScript |
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on aHandler(aParameter) |
on aHandler(aParameter) |
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say aParameter |
say aParameter |
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end receivingHandler |
end receivingHandler |
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receivingHandler(aScript)</ |
receivingHandler(aScript)</syntaxhighlight> |
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… or directly, with the passed pointer being assigned to a script object property upon receipt: |
… or directly, with the passed pointer being assigned to a script object property upon receipt: |
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< |
<syntaxhighlight lang="applescript">on aHandler(aParameter) |
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say aParameter |
say aParameter |
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end aHandler |
end aHandler |
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end receivingHandler |
end receivingHandler |
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receivingHandler(aHandler)</ |
receivingHandler(aHandler)</syntaxhighlight> |
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It's not often that handlers actually need to be passed as parameters, but passing them in script objects is usually more flexible as additional information on which they depend can then be included if required which the receiving handler doesn't need to know. |
It's not often that handlers actually need to be passed as parameters, but passing them in script objects is usually more flexible as additional information on which they depend can then be included if required which the receiving handler doesn't need to know. |
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=={{header|Arturo}}== |
=={{header|Arturo}}== |
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< |
<syntaxhighlight lang="arturo">doSthWith: function [x y f][ |
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f x y |
f x y |
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] |
] |
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print [ "add:" doSthWith 2 3 $[x y][x+y] ] |
print [ "add:" doSthWith 2 3 $[x y][x+y] ] |
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print [ "multiply:" doSthWith 2 3 $[x y][x*y] ]</ |
print [ "multiply:" doSthWith 2 3 $[x y][x*y] ]</syntaxhighlight> |
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{{out}} |
{{out}} |
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<pre>add: 5 |
<pre>add: 5 |
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=={{header|ATS}}== |
=={{header|ATS}}== |
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<syntaxhighlight lang="ats"> |
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<lang ATS> |
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#include |
#include |
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"share/atspre_staload.hats" |
"share/atspre_staload.hats" |
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Line 466: | Line 466: | ||
// |
// |
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} (* end of [main0] *) |
} (* end of [main0] *) |
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</syntaxhighlight> |
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</lang> |
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=={{header|AutoHotkey}}== |
=={{header|AutoHotkey}}== |
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<syntaxhighlight lang="autohotkey"> |
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<lang AutoHotkey> |
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f(x) { |
f(x) { |
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return "This " . x |
return "This " . x |
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show("g") ; or just name the function |
show("g") ; or just name the function |
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return |
return |
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</syntaxhighlight> |
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</lang> |
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=={{header|BBC BASIC}}== |
=={{header|BBC BASIC}}== |
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{{works with|BBC BASIC for Windows}} |
{{works with|BBC BASIC for Windows}} |
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< |
<syntaxhighlight lang="bbcbasic"> REM Test passing a function to a function: |
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PRINT FNtwo(FNone(), 10, 11) |
PRINT FNtwo(FNone(), 10, 11) |
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END |
END |
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REM Function taking a function as an argument: |
REM Function taking a function as an argument: |
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DEF FNtwo(RETURN f%, x, y) = FN(^f%)(x, y)</ |
DEF FNtwo(RETURN f%, x, y) = FN(^f%)(x, y)</syntaxhighlight> |
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'''Output:''' |
'''Output:''' |
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<pre> |
<pre> |
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A function's name in lowercase can be used to pass it as a subject, rather than a function to be executed. |
A function's name in lowercase can be used to pass it as a subject, rather than a function to be executed. |
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< |
<syntaxhighlight lang="bqn">Uniq ← ⍷ |
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•Show uniq {𝕎𝕩} 5‿6‿7‿5</ |
•Show uniq {𝕎𝕩} 5‿6‿7‿5</syntaxhighlight><syntaxhighlight lang="text">⟨ 5 6 7 ⟩</syntaxhighlight> |
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[https://mlochbaum.github.io/BQN/try.html#code=VW5pcSDihpAg4o23CgrigKJTaG93IHVuaXEge/CdlY7wnZWpfSA14oC/NuKAvzfigL81 Try It!] |
[https://mlochbaum.github.io/BQN/try.html#code=VW5pcSDihpAg4o23CgrigKJTaG93IHVuaXEge/CdlY7wnZWpfSA14oC/NuKAvzfigL81 Try It!] |
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=={{header|Bracmat}}== |
=={{header|Bracmat}}== |
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< |
<syntaxhighlight lang="bracmat">( (plus=a b.!arg:(?a.?b)&!a+!b) |
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& ( print |
& ( print |
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= text a b func |
= text a b func |
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. multiply |
. multiply |
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) |
) |
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);</ |
);</syntaxhighlight> |
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Output: |
Output: |
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<pre>add(3,7)=10 |
<pre>add(3,7)=10 |
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=={{header|Brat}}== |
=={{header|Brat}}== |
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< |
<syntaxhighlight lang="brat">add = { a, b | a + b } |
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doit = { f, a, b | f a, b } |
doit = { f, a, b | f a, b } |
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p doit ->add 1 2 #prints 3</ |
p doit ->add 1 2 #prints 3</syntaxhighlight> |
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=={{header|Burlesque}}== |
=={{header|Burlesque}}== |
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The function "m[" (map) takes a block (a 'function') as it's argument. Add 5 to every element in a list (like map (+5) [1,2,3,4] in haskell): |
The function "m[" (map) takes a block (a 'function') as it's argument. Add 5 to every element in a list (like map (+5) [1,2,3,4] in haskell): |
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< |
<syntaxhighlight lang="burlesque"> |
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blsq ) {1 2 3 4}{5.+}m[ |
blsq ) {1 2 3 4}{5.+}m[ |
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{6 7 8 9} |
{6 7 8 9} |
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</syntaxhighlight> |
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</lang> |
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=={{header|C}}== |
=={{header|C}}== |
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Definition of a function whose only parameter is a pointer to a function with no parameters and no return value: |
Definition of a function whose only parameter is a pointer to a function with no parameters and no return value: |
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< |
<syntaxhighlight lang="c">void myFuncSimple( void (*funcParameter)(void) ) |
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{ |
{ |
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/* ... */ |
/* ... */ |
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Line 563: | Line 563: | ||
/* ... */ |
/* ... */ |
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}</ |
}</syntaxhighlight> |
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Note that you ''can't'' call the passed function by " *funcParameter() ", since that would mean "call funcParameter and then apply the * operator on the returned value". |
Note that you ''can't'' call the passed function by " *funcParameter() ", since that would mean "call funcParameter and then apply the * operator on the returned value". |
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Call: |
Call: |
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< |
<syntaxhighlight lang="c">void funcToBePassed(void); |
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/* ... */ |
/* ... */ |
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myFuncSimple(&funcToBePassed);</ |
myFuncSimple(&funcToBePassed);</syntaxhighlight> |
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'''Complex example''' |
'''Complex example''' |
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Definition of a function whose return value is a pointer to int and whose only parameter is a pointer to a function, whose (in turn) return value is a pointer to double and whose only parameter is a pointer to long. |
Definition of a function whose return value is a pointer to int and whose only parameter is a pointer to a function, whose (in turn) return value is a pointer to double and whose only parameter is a pointer to long. |
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< |
<syntaxhighlight lang="c">int* myFuncComplex( double* (*funcParameter)(long* parameter) ) |
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{ |
{ |
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long inLong; |
long inLong; |
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Line 591: | Line 591: | ||
/* ... */ |
/* ... */ |
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}</ |
}</syntaxhighlight> |
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Call: |
Call: |
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< |
<syntaxhighlight lang="c">double* funcToBePassed(long* parameter); |
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/* ... */ |
/* ... */ |
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int* outInt; |
int* outInt; |
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outInt = myFuncComplex(&funcToBePassed);</ |
outInt = myFuncComplex(&funcToBePassed);</syntaxhighlight> |
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'''Pointer''' |
'''Pointer''' |
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Finally, declaration of a pointer variable of the proper type to hold such a function as myFunc: |
Finally, declaration of a pointer variable of the proper type to hold such a function as myFunc: |
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< |
<syntaxhighlight lang="c">int* (*funcPointer)( double* (*funcParameter)(long* parameter) ); |
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/* ... */ |
/* ... */ |
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funcPointer = &myFuncComplex;</ |
funcPointer = &myFuncComplex;</syntaxhighlight> |
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Of course, in a real project you shouldn't write such a convoluted code, but use some typedef instead, in order to break complexity into steps. |
Of course, in a real project you shouldn't write such a convoluted code, but use some typedef instead, in order to break complexity into steps. |
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This implementation works in all standard versions of C#. |
This implementation works in all standard versions of C#. |
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< |
<syntaxhighlight lang="csharp">using System; |
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// A delegate declaration. Because delegates are types, they can exist directly in namespaces. |
// A delegate declaration. Because delegates are types, they can exist directly in namespaces. |
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Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call(div, a, b)); |
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call(div, a, b)); |
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} |
} |
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}</ |
}</syntaxhighlight> |
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===C# 2.0: Anonymous methods=== |
===C# 2.0: Anonymous methods=== |
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Anonymous methods were added in C# 2.0. Parameter types must be specified. Anonymous methods must be "coerced" to a delegate type known at compile-time; they cannot be used with a target type of Object or to initialize implicitly typed variables. |
Anonymous methods were added in C# 2.0. Parameter types must be specified. Anonymous methods must be "coerced" to a delegate type known at compile-time; they cannot be used with a target type of Object or to initialize implicitly typed variables. |
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< |
<syntaxhighlight lang="csharp">using System; |
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delegate int Func2(int a, int b); |
delegate int Func2(int a, int b); |
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Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call(delegate(int x, int y) { return x / y; }, a, b)); |
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call(delegate(int x, int y) { return x / y; }, a, b)); |
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} |
} |
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}</ |
}</syntaxhighlight> |
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==={{anchor|C#: Lambda expressions}}C# 3.0: Lambda expressions=== |
==={{anchor|C#: Lambda expressions}}C# 3.0: Lambda expressions=== |
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{{works with|C sharp|C#|3+}} |
{{works with|C sharp|C#|3+}} |
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< |
<syntaxhighlight lang="csharp">using System; |
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class Program |
class Program |
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Line 729: | Line 729: | ||
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call((x, y) => x / y, a, b)); |
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, Call((x, y) => x / y, a, b)); |
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} |
} |
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}</ |
}</syntaxhighlight> |
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=={{header|C++}}== |
=={{header|C++}}== |
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{{works with|gcc|4.4}} |
{{works with|gcc|4.4}} |
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< |
<syntaxhighlight lang="cpp"> |
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// Use <functional> for C++11 |
// Use <functional> for C++11 |
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#include <tr1/functional> |
#include <tr1/functional> |
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first(second); |
first(second); |
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} |
} |
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</syntaxhighlight> |
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</lang> |
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===Template and Inheritance=== |
===Template and Inheritance=== |
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Line 774: | Line 774: | ||
{{works with|Visual C++|2005}} |
{{works with|Visual C++|2005}} |
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< |
<syntaxhighlight lang="cpp">#include <iostream> |
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#include <functional> |
#include <functional> |
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Line 796: | Line 796: | ||
std::cout << first(second(), 2) << std::endl; |
std::cout << first(second(), 2) << std::endl; |
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return 0; |
return 0; |
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}</ |
}</syntaxhighlight> |
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=={{header|Clean}}== |
=={{header|Clean}}== |
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Take a function as an argument and apply it to all elements in a list: |
Take a function as an argument and apply it to all elements in a list: |
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< |
<syntaxhighlight lang="clean">map f [x:xs] = [f x:map f xs] |
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map f [] = []</ |
map f [] = []</syntaxhighlight> |
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Pass a function as an argument: |
Pass a function as an argument: |
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< |
<syntaxhighlight lang="clean">incr x = x + 1 |
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Start = map incr [1..10]</ |
Start = map incr [1..10]</syntaxhighlight> |
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Do the same using a anonymous function: |
Do the same using a anonymous function: |
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< |
<syntaxhighlight lang="clean">Start = map (\x -> x + 1) [1..10]</syntaxhighlight> |
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Do the same using currying: |
Do the same using currying: |
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< |
<syntaxhighlight lang="clean">Start = map ((+) 1) [1..10]</syntaxhighlight> |
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=={{header|Clojure}}== |
=={{header|Clojure}}== |
||
< |
<syntaxhighlight lang="lisp"> |
||
(defn append-hello [s] |
(defn append-hello [s] |
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(str "Hello " s)) |
(str "Hello " s)) |
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Line 821: | Line 821: | ||
(println (modify-string append-hello "World!")) |
(println (modify-string append-hello "World!")) |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|CLU}}== |
=={{header|CLU}}== |
||
< |
<syntaxhighlight lang="clu">% Functions can be passed to other functions using the 'proctype' |
||
% type generator. The same works for iterators, using 'itertype' |
% type generator. The same works for iterators, using 'itertype' |
||
Line 847: | Line 847: | ||
do_calcs(1, 10, "Squares", square) |
do_calcs(1, 10, "Squares", square) |
||
do_calcs(1, 10, "Cubes", cube) |
do_calcs(1, 10, "Cubes", cube) |
||
end start_up</ |
end start_up</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>Squares -> 1 4 9 16 25 36 49 64 81 100 |
<pre>Squares -> 1 4 9 16 25 36 49 64 81 100 |
||
Line 856: | Line 856: | ||
Passing an anonymous function to built-in map/reduce functions: |
Passing an anonymous function to built-in map/reduce functions: |
||
< |
<syntaxhighlight lang="coffeescript">double = [1,2,3].map (x) -> x*2</syntaxhighlight> |
||
Using a function stored in a variable: |
Using a function stored in a variable: |
||
< |
<syntaxhighlight lang="coffeescript">fn = -> return 8 |
||
sum = (a, b) -> a() + b() |
sum = (a, b) -> a() + b() |
||
sum(fn, fn) # => 16 |
sum(fn, fn) # => 16 |
||
</syntaxhighlight> |
|||
</lang> |
|||
List comprehension with a function argument: |
List comprehension with a function argument: |
||
< |
<syntaxhighlight lang="coffeescript">bowl = ["Cheese", "Tomato"] |
||
smash = (ingredient) -> |
smash = (ingredient) -> |
||
Line 874: | Line 874: | ||
contents = smash ingredient for ingredient in bowl |
contents = smash ingredient for ingredient in bowl |
||
# => ["Smashed Cheese", "Smashed Tomato"] |
# => ["Smashed Cheese", "Smashed Tomato"] |
||
</syntaxhighlight> |
|||
</lang> |
|||
Nested function passing: |
Nested function passing: |
||
< |
<syntaxhighlight lang="coffeescript">double = (x) -> x*2 |
||
triple = (x) -> x*3 |
triple = (x) -> x*3 |
||
addOne = (x) -> x+1 |
addOne = (x) -> x+1 |
||
addOne triple double 2 # same as addOne(triple(double(2)))</ |
addOne triple double 2 # same as addOne(triple(double(2)))</syntaxhighlight> |
||
A function that returns a function that returns a function that returns a function that returns 2, immediately executed: |
A function that returns a function that returns a function that returns a function that returns 2, immediately executed: |
||
< |
<syntaxhighlight lang="coffeescript">(-> -> -> -> 2 )()()()() # => 2</syntaxhighlight> |
||
A function that takes a function that takes a function argument: |
A function that takes a function that takes a function argument: |
||
< |
<syntaxhighlight lang="coffeescript">((x)-> |
||
2 + x(-> 5) |
2 + x(-> 5) |
||
)((y) -> y()+3) |
)((y) -> y()+3) |
||
# result: 10</ |
# result: 10</syntaxhighlight> |
||
=={{header|Common Lisp}}== |
=={{header|Common Lisp}}== |
||
In Common Lisp, functions are [[wp:First-class_object|first class objects]], so you can pass function objects as arguments to other functions: |
In Common Lisp, functions are [[wp:First-class_object|first class objects]], so you can pass function objects as arguments to other functions: |
||
< |
<syntaxhighlight lang="lisp">CL-USER> (defun add (a b) (+ a b)) |
||
ADD |
ADD |
||
CL-USER> (add 1 2) |
CL-USER> (add 1 2) |
||
Line 906: | Line 906: | ||
CALL-IT |
CALL-IT |
||
CL-USER> (call-it #'add 1 2) |
CL-USER> (call-it #'add 1 2) |
||
3</ |
3</syntaxhighlight> |
||
The Common Lisp library makes extensive use of higher-order functions: |
The Common Lisp library makes extensive use of higher-order functions: |
||
<pre>CL-USER> (funcall #'+ 1 2 3) |
<pre>CL-USER> (funcall #'+ 1 2 3) |
||
Line 921: | Line 921: | ||
=={{header|Cowgol}}== |
=={{header|Cowgol}}== |
||
< |
<syntaxhighlight lang="cowgol">include "cowgol.coh"; |
||
# In order to pass functions around, you must first define an interface. |
# In order to pass functions around, you must first define an interface. |
||
Line 973: | Line 973: | ||
end sub; |
end sub; |
||
showAll(&operators[0], 84, 42); # example</ |
showAll(&operators[0], 84, 42); # example</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 983: | Line 983: | ||
=={{header|D}}== |
=={{header|D}}== |
||
< |
<syntaxhighlight lang="d">int hof(int a, int b, int delegate(int, int) f) { |
||
return f(a, b); |
return f(a, b); |
||
} |
} |
||
Line 991: | Line 991: | ||
writeln("Add: ", hof(2, 3, (a, b) => a + b)); |
writeln("Add: ", hof(2, 3, (a, b) => a + b)); |
||
writeln("Multiply: ", hof(2, 3, (a, b) => a * b)); |
writeln("Multiply: ", hof(2, 3, (a, b) => a * b)); |
||
}</ |
}</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>Add: 5 |
<pre>Add: 5 |
||
Multiply: 6</pre> |
Multiply: 6</pre> |
||
This longer and more systematic example shows D functions/delegates by passing each type of function/delegate to _test_ as argument. |
This longer and more systematic example shows D functions/delegates by passing each type of function/delegate to _test_ as argument. |
||
< |
<syntaxhighlight lang="d">import std.stdio; |
||
// Test the function argument. |
// Test the function argument. |
||
Line 1,056: | Line 1,056: | ||
"Literal".test(function string() { return "literal.F"; }) |
"Literal".test(function string() { return "literal.F"; }) |
||
.test(delegate string() { return "literal.D"; }); |
.test(delegate string() { return "literal.D"; }); |
||
}</ |
}</syntaxhighlight> |
||
{{out}}} |
{{out}}} |
||
<pre>Hi, Function : scope: Global (function) : immutable(char)[]()* |
<pre>Hi, Function : scope: Global (function) : immutable(char)[]()* |
||
Line 1,075: | Line 1,075: | ||
=={{header|DWScript}}== |
=={{header|DWScript}}== |
||
< |
<syntaxhighlight lang="delphi">type TFnType = function(x : Float) : Float; |
||
function First(f : TFnType) : Float; |
function First(f : TFnType) : Float; |
||
Line 1,087: | Line 1,087: | ||
end; |
end; |
||
PrintLn(First(Second));</ |
PrintLn(First(Second));</syntaxhighlight> |
||
=={{header|Dyalect}}== |
=={{header|Dyalect}}== |
||
Line 1,093: | Line 1,093: | ||
{{trans|C#}} |
{{trans|C#}} |
||
< |
<syntaxhighlight lang="dyalect">func call(f, a, b) { |
||
f(a, b) |
f(a, b) |
||
} |
} |
||
Line 1,102: | Line 1,102: | ||
print("f=add, f(\(a), \(b)) = \(call((x, y) => x + y, a, b))") |
print("f=add, f(\(a), \(b)) = \(call((x, y) => x + y, a, b))") |
||
print("f=mul, f(\(a), \(b)) = \(call((x, y) => x * y, a, b))") |
print("f=mul, f(\(a), \(b)) = \(call((x, y) => x * y, a, b))") |
||
print("f=div, f(\(a), \(b)) = \(call((x, y) => x / y, a, b))")</ |
print("f=div, f(\(a), \(b)) = \(call((x, y) => x / y, a, b))")</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 1,111: | Line 1,111: | ||
=={{header|Déjà Vu}}== |
=={{header|Déjà Vu}}== |
||
< |
<syntaxhighlight lang="dejavu">map f lst: |
||
] |
] |
||
for item in lst: |
for item in lst: |
||
Line 1,120: | Line 1,120: | ||
* 2 |
* 2 |
||
!. map @twice [ 1 2 5 ]</ |
!. map @twice [ 1 2 5 ]</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>[ 2 4 10 ]</pre> |
<pre>[ 2 4 10 ]</pre> |
||
=={{header|Draco}}== |
=={{header|Draco}}== |
||
< |
<syntaxhighlight lang="draco">/* Example functions - there are no anonymous functions */ |
||
proc nonrec square(word n) word: n*n corp |
proc nonrec square(word n) word: n*n corp |
||
proc nonrec cube(word n) word: n*n*n corp |
proc nonrec cube(word n) word: n*n*n corp |
||
Line 1,147: | Line 1,147: | ||
do_func(1, 10, square); |
do_func(1, 10, square); |
||
do_func(1, 10, cube) |
do_func(1, 10, cube) |
||
corp</ |
corp</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre> 1 4 9 16 25 36 49 64 81 100 |
<pre> 1 4 9 16 25 36 49 64 81 100 |
||
1 8 27 64 125 216 343 512 729 1000</pre> |
1 8 27 64 125 216 343 512 729 1000</pre> |
||
=={{header|E}}== |
=={{header|E}}== |
||
< |
<syntaxhighlight lang="e">def map(f, list) { |
||
var out := [] |
var out := [] |
||
for x in list { |
for x in list { |
||
Line 1,168: | Line 1,168: | ||
? def foo(x) { return -(x.size()) } |
? def foo(x) { return -(x.size()) } |
||
> map(foo, ["", "a", "bc"]) |
> map(foo, ["", "a", "bc"]) |
||
# value: [0, -1, -2]</ |
# value: [0, -1, -2]</syntaxhighlight> |
||
=={{header|ECL}}== |
=={{header|ECL}}== |
||
<lang>//a Function prototype: |
<syntaxhighlight lang="text">//a Function prototype: |
||
INTEGER actionPrototype(INTEGER v1, INTEGER v2) := 0; |
INTEGER actionPrototype(INTEGER v1, INTEGER v2) := 0; |
||
Line 1,221: | Line 1,221: | ||
OUTPUT(doMany(2, applyValue4, applyValue2,multiValues)); |
OUTPUT(doMany(2, applyValue4, applyValue2,multiValues)); |
||
// produces "24:12"</ |
// produces "24:12"</syntaxhighlight> |
||
=={{header|Efene}}== |
=={{header|Efene}}== |
||
< |
<syntaxhighlight lang="efene">first = fn (F) { |
||
F() |
F() |
||
} |
} |
||
Line 1,248: | Line 1,248: | ||
first(F2) |
first(F2) |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Elena}}== |
=={{header|Elena}}== |
||
{{trans|Smalltalk}} |
{{trans|Smalltalk}} |
||
ELENA 4.1 : |
ELENA 4.1 : |
||
< |
<syntaxhighlight lang="elena">import extensions; |
||
public program() |
public program() |
||
Line 1,260: | Line 1,260: | ||
var second := {"second"}; |
var second := {"second"}; |
||
console.printLine(first(second)) |
console.printLine(first(second)) |
||
}</ |
}</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>second</pre> |
<pre>second</pre> |
||
=={{header|Elixir}}== |
=={{header|Elixir}}== |
||
< |
<syntaxhighlight lang="elixir">iex(1)> defmodule RC do |
||
...(1)> def first(f), do: f.() |
...(1)> def first(f), do: f.() |
||
...(1)> def second, do: :hello |
...(1)> def second, do: :hello |
||
Line 1,281: | Line 1,281: | ||
#Function<20.54118792/0 in :erl_eval.expr/5> |
#Function<20.54118792/0 in :erl_eval.expr/5> |
||
iex(5)> RC.first(f) |
iex(5)> RC.first(f) |
||
:world</ |
:world</syntaxhighlight> |
||
=={{header|Erlang}}== |
=={{header|Erlang}}== |
||
Erlang functions are atoms, and they're considered different functions if their arity (the number of arguments they take) is different. As such, an Erlang function must be passed as <code>fun Function/Arity</code>, but can be used as any other variable: |
Erlang functions are atoms, and they're considered different functions if their arity (the number of arguments they take) is different. As such, an Erlang function must be passed as <code>fun Function/Arity</code>, but can be used as any other variable: |
||
< |
<syntaxhighlight lang="erlang">-module(test). |
||
-export([first/1, second/0]). |
-export([first/1, second/0]). |
||
first(F) -> F(). |
first(F) -> F(). |
||
second() -> hello.</ |
second() -> hello.</syntaxhighlight> |
||
Testing it: |
Testing it: |
||
< |
<syntaxhighlight lang="erlang">1> c(tests). |
||
{ok, tests} |
{ok, tests} |
||
2> tests:first(fun tests:second/0). |
2> tests:first(fun tests:second/0). |
||
hello |
hello |
||
3> tests:first(fun() -> anonymous_function end). |
3> tests:first(fun() -> anonymous_function end). |
||
anonymous_function</ |
anonymous_function</syntaxhighlight> |
||
=={{header|ERRE}}== |
=={{header|ERRE}}== |
||
ERRE function are limited to one-line FUNCTION, but you can write: |
ERRE function are limited to one-line FUNCTION, but you can write: |
||
<syntaxhighlight lang="erre"> |
|||
<lang ERRE> |
|||
PROGRAM FUNC_PASS |
PROGRAM FUNC_PASS |
||
Line 1,315: | Line 1,315: | ||
PRINT(TWO(10,11)) |
PRINT(TWO(10,11)) |
||
END PROGRAM |
END PROGRAM |
||
</syntaxhighlight> |
|||
</lang> |
|||
Answer is 442 |
Answer is 442 |
||
=={{header|Euler Math Toolbox}}== |
=={{header|Euler Math Toolbox}}== |
||
<syntaxhighlight lang="euler math toolbox"> |
|||
<lang Euler Math Toolbox> |
|||
>function f(x,a) := x^a-a^x |
>function f(x,a) := x^a-a^x |
||
>function dof (f$:string,x) := f$(x,args()); |
>function dof (f$:string,x) := f$(x,args()); |
||
Line 1,326: | Line 1,326: | ||
[ -1 0 1 0 -7 ] |
[ -1 0 1 0 -7 ] |
||
>plot2d("f",1,5;2): |
>plot2d("f",1,5;2): |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Euphoria}}== |
=={{header|Euphoria}}== |
||
< |
<syntaxhighlight lang="euphoria">procedure use(integer fi, integer a, integer b) |
||
print(1,call_func(fi,{a,b})) |
print(1,call_func(fi,{a,b})) |
||
end procedure |
end procedure |
||
Line 1,337: | Line 1,337: | ||
end function |
end function |
||
use(routine_id("add"),23,45)</ |
use(routine_id("add"),23,45)</syntaxhighlight> |
||
=={{header|F Sharp|F#}}== |
=={{header|F Sharp|F#}}== |
||
We define a function that takes another function f as an argument and applies that function twice to the argument x: |
We define a function that takes another function f as an argument and applies that function twice to the argument x: |
||
< |
<syntaxhighlight lang="fsharp">> let twice f x = f (f x);; |
||
val twice : ('a -> 'a) -> 'a -> 'a |
val twice : ('a -> 'a) -> 'a -> 'a |
||
> twice System.Math.Sqrt 81.0;; |
> twice System.Math.Sqrt 81.0;; |
||
val it : float = 3.0</ |
val it : float = 3.0</syntaxhighlight> |
||
Another example, using an operator as a function: |
Another example, using an operator as a function: |
||
< |
<syntaxhighlight lang="fsharp">> List.map2 (+) [1;2;3] [3;2;1];; |
||
val it : int list = [4; 4; 4]</ |
val it : int list = [4; 4; 4]</syntaxhighlight> |
||
=={{header|Factor}}== |
=={{header|Factor}}== |
||
Using words (factor's functions) : |
Using words (factor's functions) : |
||
< |
<syntaxhighlight lang="factor">USING: io ; |
||
IN: rosetacode |
IN: rosetacode |
||
: argument-function1 ( -- ) "Hello World!" print ; |
: argument-function1 ( -- ) "Hello World!" print ; |
||
Line 1,367: | Line 1,367: | ||
! Stack effect has to be written for runtime computed values : |
! Stack effect has to be written for runtime computed values : |
||
: calling-function3 ( bool -- ) \ argument-function1 \ argument-function2 ? execute( -- ) ; |
: calling-function3 ( bool -- ) \ argument-function1 \ argument-function2 ? execute( -- ) ; |
||
</syntaxhighlight> |
|||
</lang> |
|||
( scratchpad ) |
( scratchpad ) |
||
Line 1,382: | Line 1,382: | ||
=={{header|FALSE}}== |
=={{header|FALSE}}== |
||
Anonymous code blocks are the basis of FALSE control flow and function definition. These blocks may be passed on the stack as with any other parameter. |
Anonymous code blocks are the basis of FALSE control flow and function definition. These blocks may be passed on the stack as with any other parameter. |
||
< |
<syntaxhighlight lang="false">[f:[$0>][@@\f;!\1-]#%]r: { reduce n stack items using the given basis and binary function } |
||
1 2 3 4 0 4[+]r;!." " { 10 } |
1 2 3 4 0 4[+]r;!." " { 10 } |
||
1 2 3 4 1 4[*]r;!." " { 24 } |
1 2 3 4 1 4[*]r;!." " { 24 } |
||
1 2 3 4 0 4[$*+]r;!. { 30 }</ |
1 2 3 4 0 4[$*+]r;!. { 30 }</syntaxhighlight> |
||
=={{header|Fantom}}== |
=={{header|Fantom}}== |
||
< |
<syntaxhighlight lang="fantom"> |
||
class Main |
class Main |
||
{ |
{ |
||
Line 1,405: | Line 1,405: | ||
} |
} |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Forth}}== |
=={{header|Forth}}== |
||
Forth words can be referenced on the stack via their ''execution token'' or XT. An XT is obtained from a word via the quote operator, and invoked via '''EXECUTE'''. Anonymous functions may be defined via ''':NONAME''' (returning an XT) instead of a standard colon definition. |
Forth words can be referenced on the stack via their ''execution token'' or XT. An XT is obtained from a word via the quote operator, and invoked via '''EXECUTE'''. Anonymous functions may be defined via ''':NONAME''' (returning an XT) instead of a standard colon definition. |
||
< |
<syntaxhighlight lang="forth">: square dup * ; |
||
: cube dup dup * * ; |
: cube dup dup * * ; |
||
: map. ( xt addr len -- ) |
: map. ( xt addr len -- ) |
||
Line 1,418: | Line 1,418: | ||
' square array 5 map. cr \ 1 4 9 16 25 |
' square array 5 map. cr \ 1 4 9 16 25 |
||
' cube array 5 map. cr \ 1 8 27 64 125 |
' cube array 5 map. cr \ 1 8 27 64 125 |
||
:noname 2* 1+ ; array 5 map. cr \ 3 5 7 9 11</ |
:noname 2* 1+ ; array 5 map. cr \ 3 5 7 9 11</syntaxhighlight> |
||
=={{header|Fortran}}== |
=={{header|Fortran}}== |
||
{{works with|Fortran|90 and later}} |
{{works with|Fortran|90 and later}} |
||
use the EXTERNAL attribute to show the dummy argument is another function rather than a data object. i.e. |
use the EXTERNAL attribute to show the dummy argument is another function rather than a data object. i.e. |
||
< |
<syntaxhighlight lang="fortran">FUNCTION FUNC3(FUNC1, FUNC2, x, y) |
||
REAL, EXTERNAL :: FUNC1, FUNC2 |
REAL, EXTERNAL :: FUNC1, FUNC2 |
||
REAL :: FUNC3 |
REAL :: FUNC3 |
||
Line 1,429: | Line 1,429: | ||
FUNC3 = FUNC1(x) * FUNC2(y) |
FUNC3 = FUNC1(x) * FUNC2(y) |
||
END FUNCTION FUNC3</ |
END FUNCTION FUNC3</syntaxhighlight> |
||
Another way is to put the functions you want to pass in a module: |
Another way is to put the functions you want to pass in a module: |
||
< |
<syntaxhighlight lang="fortran">module FuncContainer |
||
implicit none |
implicit none |
||
contains |
contains |
||
Line 1,482: | Line 1,482: | ||
end subroutine asubroutine |
end subroutine asubroutine |
||
end program FuncArg</ |
end program FuncArg</syntaxhighlight> |
||
=={{header|FreeBASIC}}== |
=={{header|FreeBASIC}}== |
||
< |
<syntaxhighlight lang="freebasic">' FB 1.05.0 Win64 |
||
Function square(n As Integer) As Integer |
Function square(n As Integer) As Integer |
||
Line 1,507: | Line 1,507: | ||
Print |
Print |
||
Print "Press any key to quit" |
Print "Press any key to quit" |
||
Sleep</ |
Sleep</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 1,518: | Line 1,518: | ||
The following defines an anonymous function and passes it to another function. In this case, the anonymous function is a comparison function that sorts by string length. |
The following defines an anonymous function and passes it to another function. In this case, the anonymous function is a comparison function that sorts by string length. |
||
< |
<syntaxhighlight lang="frink"> |
||
cmpFunc = {|a,b| length[a] <=> length[b]} |
cmpFunc = {|a,b| length[a] <=> length[b]} |
||
a = ["tree", "apple", "bee", "monkey", "z"] |
a = ["tree", "apple", "bee", "monkey", "z"] |
||
sort[a, cmpFunc] |
sort[a, cmpFunc] |
||
</syntaxhighlight> |
|||
</lang> |
|||
You can also look up functions by name and number of arguments. The following is equivalent to the previous example. |
You can also look up functions by name and number of arguments. The following is equivalent to the previous example. |
||
< |
<syntaxhighlight lang="frink"> |
||
lengthCompare[a,b] := length[a] <=> length[b] |
lengthCompare[a,b] := length[a] <=> length[b] |
||
Line 1,533: | Line 1,533: | ||
a = ["tree", "apple", "bee", "monkey", "z"] |
a = ["tree", "apple", "bee", "monkey", "z"] |
||
sort[a, func] |
sort[a, func] |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|FutureBasic}}== |
=={{header|FutureBasic}}== |
||
< |
<syntaxhighlight lang="futurebasic">window 1 |
||
dim as pointer functionOneAddress |
dim as pointer functionOneAddress |
||
Line 1,547: | Line 1,547: | ||
print fn FunctionTwo( 12, 12 ) |
print fn FunctionTwo( 12, 12 ) |
||
HandleEvents</ |
HandleEvents</syntaxhighlight> |
||
Output: |
Output: |
||
Line 1,563: | Line 1,563: | ||
=={{header|GAP}}== |
=={{header|GAP}}== |
||
< |
<syntaxhighlight lang="gap">Eval := function(f, x) |
||
return f(x); |
return f(x); |
||
end; |
end; |
||
Eval(x -> x^3, 7); |
Eval(x -> x^3, 7); |
||
# 343</ |
# 343</syntaxhighlight> |
||
=={{header|Go}}== |
=={{header|Go}}== |
||
< |
<syntaxhighlight lang="go">package main |
||
import "fmt" |
import "fmt" |
||
func func1(f func(string) string) string { return f("a string") } |
func func1(f func(string) string) string { return f("a string") } |
||
func func2(s string) string { return "func2 called with " + s } |
func func2(s string) string { return "func2 called with " + s } |
||
func main() { fmt.Println(func1(func2)) }</ |
func main() { fmt.Println(func1(func2)) }</syntaxhighlight> |
||
=={{header|Groovy}}== |
=={{header|Groovy}}== |
||
As [[closures]]: |
As [[closures]]: |
||
< |
<syntaxhighlight lang="groovy">first = { func -> func() } |
||
second = { println "second" } |
second = { println "second" } |
||
first(second)</ |
first(second)</syntaxhighlight> |
||
As functions: |
As functions: |
||
< |
<syntaxhighlight lang="groovy">def first(func) { func() } |
||
def second() { println "second" } |
def second() { println "second" } |
||
first(this.&second)</ |
first(this.&second)</syntaxhighlight> |
||
=={{header|Haskell}}== |
=={{header|Haskell}}== |
||
Line 1,595: | Line 1,595: | ||
A function is just a value that wants arguments: |
A function is just a value that wants arguments: |
||
< |
<syntaxhighlight lang="haskell">func1 f = f "a string" |
||
func2 s = "func2 called with " ++ s |
func2 s = "func2 called with " ++ s |
||
main = putStrLn $ func1 func2</ |
main = putStrLn $ func1 func2</syntaxhighlight> |
||
Or, with an anonymous function: |
Or, with an anonymous function: |
||
< |
<syntaxhighlight lang="haskell">func f = f 1 2 |
||
main = print $ func (\x y -> x+y) |
main = print $ func (\x y -> x+y) |
||
-- output: 3</ |
-- output: 3</syntaxhighlight> |
||
Note that <tt>func (\x y -> x+y)</tt> is equivalent to <tt>func (+)</tt>. (Operators are functions too.) |
Note that <tt>func (\x y -> x+y)</tt> is equivalent to <tt>func (+)</tt>. (Operators are functions too.) |
||
=={{header|Icon}} and {{header|Unicon}}== |
=={{header|Icon}} and {{header|Unicon}}== |
||
< |
<syntaxhighlight lang="icon"> procedure main() |
||
local lst |
local lst |
||
lst := [10, 20, 30, 40] |
lst := [10, 20, 30, 40] |
||
Line 1,619: | Line 1,619: | ||
procedure callback(arg) |
procedure callback(arg) |
||
write("->", arg) |
write("->", arg) |
||
end</ |
end</syntaxhighlight> |
||
=={{header|Inform 6}}== |
=={{header|Inform 6}}== |
||
As in C, functions in Inform 6 are not first-class, but pointers to functions can be used. |
As in C, functions in Inform 6 are not first-class, but pointers to functions can be used. |
||
< |
<syntaxhighlight lang="inform6">[ func; |
||
print "Hello^"; |
print "Hello^"; |
||
]; |
]; |
||
Line 1,633: | Line 1,633: | ||
[ Main; |
[ Main; |
||
call_func(func); |
call_func(func); |
||
];</ |
];</syntaxhighlight> |
||
=={{header|Inform 7}}== |
=={{header|Inform 7}}== |
||
Phrases usually aren't defined with names, only with invocation syntax. A phrase must be given a name (here, "addition" and "multiplication") in order to be passed as a phrase value. |
Phrases usually aren't defined with names, only with invocation syntax. A phrase must be given a name (here, "addition" and "multiplication") in order to be passed as a phrase value. |
||
< |
<syntaxhighlight lang="inform7">Higher Order Functions is a room. |
||
To decide which number is (N - number) added to (M - number) (this is addition): |
To decide which number is (N - number) added to (M - number) (this is addition): |
||
Line 1,651: | Line 1,651: | ||
demonstrate addition as "Add"; |
demonstrate addition as "Add"; |
||
demonstrate multiplication as "Mul"; |
demonstrate multiplication as "Mul"; |
||
end the story.</ |
end the story.</syntaxhighlight> |
||
=={{header|J}}== |
=={{header|J}}== |
||
Line 1,657: | Line 1,657: | ||
''Adverbs'' take a single verb or noun argument and ''conjunctions'' take two. For example,<tt> / </tt>(insert)<tt> \ </tt>(prefix) and<tt> \. </tt>(suffix) are adverbs and <tt> @ </tt>(atop), <tt> & </tt>(bond or compose) and <tt> ^: </tt>(power) are conjunctions. The following expressions illustrate their workings. |
''Adverbs'' take a single verb or noun argument and ''conjunctions'' take two. For example,<tt> / </tt>(insert)<tt> \ </tt>(prefix) and<tt> \. </tt>(suffix) are adverbs and <tt> @ </tt>(atop), <tt> & </tt>(bond or compose) and <tt> ^: </tt>(power) are conjunctions. The following expressions illustrate their workings. |
||
< |
<syntaxhighlight lang="j"> + / 3 1 4 1 5 9 NB. sum |
||
23 |
23 |
||
>./ 3 1 4 1 5 9 NB. max |
>./ 3 1 4 1 5 9 NB. max |
||
Line 1,687: | Line 1,687: | ||
1 1.5 1.41667 1.41422 1.41421 |
1 1.5 1.41667 1.41422 1.41421 |
||
f^:(i.5) 1x NB. rational approximations to sqrt 2 |
f^:(i.5) 1x NB. rational approximations to sqrt 2 |
||
1 3r2 17r12 577r408 665857r470832</ |
1 3r2 17r12 577r408 665857r470832</syntaxhighlight> |
||
Adverbs and conjunctions may also be user defined |
Adverbs and conjunctions may also be user defined |
||
< |
<syntaxhighlight lang="j"> + conjunction def 'u' - |
||
+ |
+ |
||
+ conjunction def 'v' - |
+ conjunction def 'v' - |
||
Line 1,698: | Line 1,698: | ||
110 |
110 |
||
^ conjunction def '10 v 2 u y' * 11 |
^ conjunction def '10 v 2 u y' * 11 |
||
20480</ |
20480</syntaxhighlight> |
||
=={{header|Java}}== |
=={{header|Java}}== |
||
Line 1,704: | Line 1,704: | ||
There is no real callback in Java like in C or C++, but we can do the same as swing does for executing an event. We need to create an interface that has the method we want to call or create one that will call the method we want to call. The following example uses the second way. |
There is no real callback in Java like in C or C++, but we can do the same as swing does for executing an event. We need to create an interface that has the method we want to call or create one that will call the method we want to call. The following example uses the second way. |
||
< |
<syntaxhighlight lang="java">public class NewClass { |
||
public NewClass() { |
public NewClass() { |
||
Line 1,729: | Line 1,729: | ||
interface AnEventOrCallback { |
interface AnEventOrCallback { |
||
public void call(); |
public void call(); |
||
}</ |
}</syntaxhighlight> |
||
From Java 8, lambda expressions may be used. Example (from Oracle): |
From Java 8, lambda expressions may be used. Example (from Oracle): |
||
< |
<syntaxhighlight lang="java">public class ListenerTest { |
||
public static void main(String[] args) { |
public static void main(String[] args) { |
||
JButton testButton = new JButton("Test Button"); |
JButton testButton = new JButton("Test Button"); |
||
Line 1,750: | Line 1,750: | ||
frame.setVisible(true); |
frame.setVisible(true); |
||
} |
} |
||
}</ |
}</syntaxhighlight> |
||
=={{header|JavaScript}}== |
=={{header|JavaScript}}== |
||
< |
<syntaxhighlight lang="javascript">function first (func) { |
||
return func(); |
return func(); |
||
} |
} |
||
Line 1,763: | Line 1,763: | ||
var result = first(second); |
var result = first(second); |
||
result = first(function () { return "third"; });</ |
result = first(function () { return "third"; });</syntaxhighlight> |
||
An example with anonymous functions and uses in the core library |
An example with anonymous functions and uses in the core library |
||
Line 1,769: | Line 1,769: | ||
{{works with|Firefox|1.5}} for methods <code>filter</code> and <code>map</code>. |
{{works with|Firefox|1.5}} for methods <code>filter</code> and <code>map</code>. |
||
< |
<syntaxhighlight lang="javascript">>>> var array = [2, 4, 5, 13, 18, 24, 34, 97]; |
||
>>> array |
>>> array |
||
[2, 4, 5, 13, 18, 24, 34, 97] |
[2, 4, 5, 13, 18, 24, 34, 97] |
||
Line 1,795: | Line 1,795: | ||
// sort the array from largest to smallest |
// sort the array from largest to smallest |
||
>>> array.sort(function (a, b) { return a < b }); |
>>> array.sort(function (a, b) { return a < b }); |
||
[97, 34, 24, 18, 13, 5, 4, 2]</ |
[97, 34, 24, 18, 13, 5, 4, 2]</syntaxhighlight> |
||
=={{header|Joy}}== |
=={{header|Joy}}== |
||
This example is taken from V. |
This example is taken from V. |
||
Define first as multiplying two numbers on the stack. |
Define first as multiplying two numbers on the stack. |
||
<syntaxhighlight lang= |
<syntaxhighlight lang="joy">DEFINE first == *.</syntaxhighlight> |
||
There will be a warning about overwriting builtin first. |
There will be a warning about overwriting builtin first. |
||
Define second as interpreting the passed quotation on the stack. |
Define second as interpreting the passed quotation on the stack. |
||
<syntaxhighlight lang= |
<syntaxhighlight lang="joy">DEFINE second == i.</syntaxhighlight> |
||
Pass first enclosed in quotes to second. |
Pass first enclosed in quotes to second. |
||
<syntaxhighlight lang= |
<syntaxhighlight lang="joy">2 3 [first] second.</syntaxhighlight> |
||
The program prints 6. |
The program prints 6. |
||
Line 1,818: | Line 1,818: | ||
====Example 1: "hello blue world"==== |
====Example 1: "hello blue world"==== |
||
< |
<syntaxhighlight lang="jq">def foo( filter ): |
||
("world" | filter) as $str |
("world" | filter) as $str |
||
| "hello \($str)" ; |
| "hello \($str)" ; |
||
Line 1,826: | Line 1,826: | ||
foo( blue ) # prints "hello blue world" |
foo( blue ) # prints "hello blue world" |
||
</syntaxhighlight> |
|||
</lang> |
|||
====Example 2: g(add; 2; 3)==== |
====Example 2: g(add; 2; 3)==== |
||
<syntaxhighlight lang="jq"> |
|||
<lang jq> |
|||
def g(f; x; y): [x,y] | f; |
def g(f; x; y): [x,y] | f; |
||
g(add; 2; 3) # => 5</ |
g(add; 2; 3) # => 5</syntaxhighlight> |
||
====Example: Built-in higher-order functions==== |
====Example: Built-in higher-order functions==== |
||
In the following sequence of interactions, we pass the function *is_even/0* to some built-in higher order functions. *is_even/0* is defined as follows: |
In the following sequence of interactions, we pass the function *is_even/0* to some built-in higher order functions. *is_even/0* is defined as follows: |
||
< |
<syntaxhighlight lang="jq">def is_even: |
||
if floor == . then (. % 2) == 0 |
if floor == . then (. % 2) == 0 |
||
else error("is_even expects its input to be an integer") |
else error("is_even expects its input to be an integer") |
||
end;</ |
end;</syntaxhighlight><syntaxhighlight lang="jq"> |
||
# Are all integers between 1 and 5 even? |
# Are all integers between 1 and 5 even? |
||
# For this example, we will use all/2 even |
# For this example, we will use all/2 even |
||
Line 1,863: | Line 1,863: | ||
false |
false |
||
true |
true |
||
false</ |
false</syntaxhighlight> |
||
=={{header|Julia}}== |
=={{header|Julia}}== |
||
<syntaxhighlight lang="julia"> |
|||
<lang Julia> |
|||
function foo(x) |
function foo(x) |
||
str = x("world") |
str = x("world") |
||
Line 1,873: | Line 1,873: | ||
end |
end |
||
foo(y -> "blue $y") # prints "hello blue world" |
foo(y -> "blue $y") # prints "hello blue world" |
||
</syntaxhighlight> |
|||
</lang> |
|||
The above code snippet defines a named function, <tt>foo</tt>, which takes a single argument, which is a <tt>Function</tt>. |
The above code snippet defines a named function, <tt>foo</tt>, which takes a single argument, which is a <tt>Function</tt>. |
||
Line 1,879: | Line 1,879: | ||
In the final line, <tt>foo</tt> is called with an anonymous function that takes a string, and returns a that string with <tt>"blue "</tt> preppended to it. |
In the final line, <tt>foo</tt> is called with an anonymous function that takes a string, and returns a that string with <tt>"blue "</tt> preppended to it. |
||
<syntaxhighlight lang="julia"> |
|||
<lang Julia> |
|||
function g(x,y,z) |
function g(x,y,z) |
||
x(y,z) |
x(y,z) |
||
end |
end |
||
println(g(+,2,3)) # prints 5 |
println(g(+,2,3)) # prints 5 |
||
</syntaxhighlight> |
|||
</lang> |
|||
This code snippet defines a named function <tt>g</tt> that takes three arguments: <tt>x</tt> is a function to call, and <tt>y</tt> and <tt>z</tt> are the values to call <tt>x</tt> on. |
This code snippet defines a named function <tt>g</tt> that takes three arguments: <tt>x</tt> is a function to call, and <tt>y</tt> and <tt>z</tt> are the values to call <tt>x</tt> on. |
||
Line 1,890: | Line 1,890: | ||
In the following interactive session, we pass the function iseven to a few higher order functions. The function iseven returns true if its argument is an even integer, false if it is an odd integer, and throws an error otherwise. The second argument to the functions is a range of integers, specifically the five integers between 1 and 5 included. |
In the following interactive session, we pass the function iseven to a few higher order functions. The function iseven returns true if its argument is an even integer, false if it is an odd integer, and throws an error otherwise. The second argument to the functions is a range of integers, specifically the five integers between 1 and 5 included. |
||
< |
<syntaxhighlight lang="julia">julia> all(iseven, 1:5) # not all integers between 1 and 5 are even. |
||
false |
false |
||
Line 1,911: | Line 1,911: | ||
true |
true |
||
false |
false |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Klingphix}}== |
=={{header|Klingphix}}== |
||
< |
<syntaxhighlight lang="klingphix">:+2 + 2 + ; |
||
:*2 * 2 * ; |
:*2 * 2 * ; |
||
Line 1,922: | Line 1,922: | ||
8 4 @*2 apply print nl |
8 4 @*2 apply print nl |
||
" " input</ |
" " input</syntaxhighlight> |
||
=={{header|Kotlin}}== |
=={{header|Kotlin}}== |
||
Kotlin is a functional language. Example showing how the builtin map function is used to get the average value of a transformed list of numbers: |
Kotlin is a functional language. Example showing how the builtin map function is used to get the average value of a transformed list of numbers: |
||
< |
<syntaxhighlight lang="scala">fun main(args: Array<String>) { |
||
val list = listOf(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0) |
val list = listOf(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0) |
||
val a = list.map({ x -> x + 2 }).average() |
val a = list.map({ x -> x + 2 }).average() |
||
Line 1,932: | Line 1,932: | ||
val g = list.map({ x -> x * x * x }).average() |
val g = list.map({ x -> x * x * x }).average() |
||
println("A = %f G = %f H = %f".format(a, g, h)) |
println("A = %f G = %f H = %f".format(a, g, h)) |
||
}</ |
}</syntaxhighlight> |
||
Another example showing the syntactic sugar available to Kotlin developers which allows them to put the lambda expression out of the parenthesis whenever the function is the last argument of the higher order function. Notice the usage of the inline modifier, which inlines the bytecode of the argument function on the callsite, reducing the object creation overhead (an optimization for pre Java 8 JVM environments, like Android) (translation from Scala example): |
Another example showing the syntactic sugar available to Kotlin developers which allows them to put the lambda expression out of the parenthesis whenever the function is the last argument of the higher order function. Notice the usage of the inline modifier, which inlines the bytecode of the argument function on the callsite, reducing the object creation overhead (an optimization for pre Java 8 JVM environments, like Android) (translation from Scala example): |
||
< |
<syntaxhighlight lang="scala">inline fun higherOrderFunction(x: Int, y: Int, function: (Int, Int) -> Int) = function(x, y) |
||
fun main(args: Array<String>) { |
fun main(args: Array<String>) { |
||
val result = higherOrderFunction(3, 5) { x, y -> x + y } |
val result = higherOrderFunction(3, 5) { x, y -> x + y } |
||
println(result) |
println(result) |
||
}</ |
}</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 1,946: | Line 1,946: | ||
=={{header|Lambdatalk}}== |
=={{header|Lambdatalk}}== |
||
<syntaxhighlight lang="scheme"> |
|||
<lang Scheme> |
|||
{def add |
{def add |
||
{lambda {:f :g :x} |
{lambda {:f :g :x} |
||
Line 1,959: | Line 1,959: | ||
{S.reduce + {S.serie 1 10}} |
{S.reduce + {S.serie 1 10}} |
||
-> 55 |
-> 55 |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Lily}}== |
=={{header|Lily}}== |
||
< |
<syntaxhighlight lang="lily">define square(x: Integer): Integer |
||
{ |
{ |
||
return x * x |
return x * x |
||
Line 1,987: | Line 1,987: | ||
# Calling user-defined transformation. |
# Calling user-defined transformation. |
||
print(apply("123", String.parse_i)) # Some(123)</ |
print(apply("123", String.parse_i)) # Some(123)</syntaxhighlight> |
||
=={{header|Lingo}}== |
=={{header|Lingo}}== |
||
Lingo doesn't support first-class functions. But functions can be passed as "symbols", and then be called via Lingo's 'call' command. Global functions - i.e. either built-in functions or user-defined functions in movie scripts - are always methods of the core '_movie' object, for other object functions (methods) also the object has to be specified. Here as example an implementation of a generic "map" function: |
Lingo doesn't support first-class functions. But functions can be passed as "symbols", and then be called via Lingo's 'call' command. Global functions - i.e. either built-in functions or user-defined functions in movie scripts - are always methods of the core '_movie' object, for other object functions (methods) also the object has to be specified. Here as example an implementation of a generic "map" function: |
||
< |
<syntaxhighlight lang="lingo">-- in some movie script |
||
---------------------------------------- |
---------------------------------------- |
||
-- Runs provided function (of some object) on all elements of the provided list, returns results as new list |
-- Runs provided function (of some object) on all elements of the provided list, returns results as new list |
||
Line 2,008: | Line 2,008: | ||
end repeat |
end repeat |
||
return res |
return res |
||
end</ |
end</syntaxhighlight> |
||
< |
<syntaxhighlight lang="lingo">l = [1, 2, 3] |
||
-- passes the built-in function 'sin' (which is a method of the _movie object) as argument to map |
-- passes the built-in function 'sin' (which is a method of the _movie object) as argument to map |
||
Line 2,016: | Line 2,016: | ||
put res |
put res |
||
-- [0.8415, 0.9093, 0.1411]</ |
-- [0.8415, 0.9093, 0.1411]</syntaxhighlight> |
||
=={{header|Logo}}== |
=={{header|Logo}}== |
||
You can pass the quoted symbol for the function and invoke it with RUN. |
You can pass the quoted symbol for the function and invoke it with RUN. |
||
< |
<syntaxhighlight lang="logo">to printstuff |
||
print "stuff |
print "stuff |
||
end |
end |
||
Line 2,027: | Line 2,027: | ||
end |
end |
||
runstuff "printstuff ; stuff |
runstuff "printstuff ; stuff |
||
runstuff [print [also stuff]] ; also stuff</ |
runstuff [print [also stuff]] ; also stuff</syntaxhighlight> |
||
=={{header|Lua}}== |
=={{header|Lua}}== |
||
Lua functions are first-class: |
Lua functions are first-class: |
||
< |
<syntaxhighlight lang="lua">a = function() return 1 end |
||
b = function(r) print( r() ) end |
b = function(r) print( r() ) end |
||
b(a)</ |
b(a)</syntaxhighlight> |
||
=={{header|Luck}}== |
=={{header|Luck}}== |
||
Higher-order functions can be used to implement conditional expressions: |
Higher-order functions can be used to implement conditional expressions: |
||
< |
<syntaxhighlight lang="luck">function lambda_true(x: 'a)(y: 'a): 'a = x;; |
||
function lambda_false(x: 'a)(y: 'a): 'a = y;; |
function lambda_false(x: 'a)(y: 'a): 'a = y;; |
||
function lambda_if(c:'a -> 'a -> 'a )(t: 'a)(f: 'a): 'a = c(t)(f);; |
function lambda_if(c:'a -> 'a -> 'a )(t: 'a)(f: 'a): 'a = c(t)(f);; |
||
print( lambda_if(lambda_true)("condition was true")("condition was false") );;</ |
print( lambda_if(lambda_true)("condition was true")("condition was false") );;</syntaxhighlight> |
||
=={{header|M2000 Interpreter}}== |
=={{header|M2000 Interpreter}}== |
||
We can pass by reference a standard function, or we can pass by value a lambda function (also we can pass by reference as reference to lambda function) |
We can pass by reference a standard function, or we can pass by value a lambda function (also we can pass by reference as reference to lambda function) |
||
<syntaxhighlight lang="m2000 interpreter"> |
|||
<lang M2000 Interpreter> |
|||
Function Foo (x) { |
Function Foo (x) { |
||
=x**2 |
=x**2 |
||
Line 2,062: | Line 2,062: | ||
Print Bar(&K.MulZ(), 20)=200 |
Print Bar(&K.MulZ(), 20)=200 |
||
Print K.Z=11 |
Print K.Z=11 |
||
</syntaxhighlight> |
|||
</lang> |
|||
Example using lambda function |
Example using lambda function |
||
<syntaxhighlight lang="m2000 interpreter"> |
|||
<lang M2000 Interpreter> |
|||
Foo = Lambda k=1 (x)-> { |
Foo = Lambda k=1 (x)-> { |
||
k+=2 |
k+=2 |
||
Line 2,094: | Line 2,094: | ||
Print Bar2(&NewFoo, 20)=409 |
Print Bar2(&NewFoo, 20)=409 |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Mathematica}} / {{header|Wolfram Language}}== |
=={{header|Mathematica}} / {{header|Wolfram Language}}== |
||
Passing 3 arguments and a value (could be a number, variable, graphic or a function as well, actually it could be ''anything''), and composing them in an unusual way: |
Passing 3 arguments and a value (could be a number, variable, graphic or a function as well, actually it could be ''anything''), and composing them in an unusual way: |
||
< |
<syntaxhighlight lang="mathematica">PassFunc[f_, g_, h_, x_] := f[g[x]*h[x]] |
||
PassFunc[Tan, Cos, Sin, x] |
PassFunc[Tan, Cos, Sin, x] |
||
% /. x -> 0.12 |
% /. x -> 0.12 |
||
PassFunc[Tan, Cos, Sin, 0.12]</ |
PassFunc[Tan, Cos, Sin, 0.12]</syntaxhighlight> |
||
gives back: |
gives back: |
||
< |
<syntaxhighlight lang="mathematica">Tan[Cos[x] Sin[x]] |
||
0.119414 |
0.119414 |
||
0.119414</ |
0.119414</syntaxhighlight> |
||
=={{header|MATLAB}} / {{header|Octave}}== |
=={{header|MATLAB}} / {{header|Octave}}== |
||
< |
<syntaxhighlight lang="matlab"> F1=@sin; % F1 refers to function sin() |
||
F2=@cos; % F2 refers to function cos() |
F2=@cos; % F2 refers to function cos() |
||
Line 2,125: | Line 2,125: | ||
F4 = 'cos'; |
F4 = 'cos'; |
||
feval(F3,pi/4) |
feval(F3,pi/4) |
||
feval(F4,pi/4)</ |
feval(F4,pi/4)</syntaxhighlight> |
||
=={{header|Maxima}}== |
=={{header|Maxima}}== |
||
< |
<syntaxhighlight lang="maxima">callee(n) := (print(sconcat("called with ", n)), n + 1)$ |
||
caller(f, n) := sum(f(i), i, 1, n)$ |
caller(f, n) := sum(f(i), i, 1, n)$ |
||
caller(callee, 3); |
caller(callee, 3); |
||
"called with 1" |
"called with 1" |
||
"called with 2" |
"called with 2" |
||
"called with 3"</ |
"called with 3"</syntaxhighlight> |
||
=={{header|MAXScript}}== |
=={{header|MAXScript}}== |
||
< |
<syntaxhighlight lang="maxscript">fn second = |
||
( |
( |
||
print "Second" |
print "Second" |
||
Line 2,146: | Line 2,146: | ||
) |
) |
||
first second</ |
first second</syntaxhighlight> |
||
=={{header|Metafont}}== |
=={{header|Metafont}}== |
||
Line 2,152: | Line 2,152: | ||
We can simulate this by using <code>scantokens</code>, which ''digests'' a string as if it would be a source input. |
We can simulate this by using <code>scantokens</code>, which ''digests'' a string as if it would be a source input. |
||
< |
<syntaxhighlight lang="metafont">def calcit(expr v, s) = scantokens(s & decimal v) enddef; |
||
t := calcit(100.4, "sind"); |
t := calcit(100.4, "sind"); |
||
show t; |
show t; |
||
end</ |
end</syntaxhighlight> |
||
=={{header|МК-61/52}}== |
=={{header|МК-61/52}}== |
||
<lang>6 ПП 04 |
<syntaxhighlight lang="text">6 ПП 04 |
||
П7 КПП7 В/О |
П7 КПП7 В/О |
||
1 В/О</ |
1 В/О</syntaxhighlight> |
||
''Note'': as the receiver of argument used register ''Р7''; the result is "1" on the indicator. |
''Note'': as the receiver of argument used register ''Р7''; the result is "1" on the indicator. |
||
=={{header|Modula-3}}== |
=={{header|Modula-3}}== |
||
< |
<syntaxhighlight lang="modula3">MODULE Proc EXPORTS Main; |
||
IMPORT IO; |
IMPORT IO; |
||
Line 2,184: | Line 2,184: | ||
BEGIN |
BEGIN |
||
First(Second); |
First(Second); |
||
END Proc.</ |
END Proc.</syntaxhighlight> |
||
=={{header|Morfa}}== |
=={{header|Morfa}}== |
||
{{trans|D}} |
{{trans|D}} |
||
< |
<syntaxhighlight lang="morfa"> |
||
func g(a: int, b: int, f: func(int,int): int): int |
func g(a: int, b: int, f: func(int,int): int): int |
||
{ |
{ |
||
Line 2,201: | Line 2,201: | ||
println("Multiply: ", g(2, 3, func(a: int, b: int) { return a * b; })); |
println("Multiply: ", g(2, 3, func(a: int, b: int) { return a * b; })); |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Nanoquery}}== |
=={{header|Nanoquery}}== |
||
{{trans|Python}} |
{{trans|Python}} |
||
< |
<syntaxhighlight lang="nanoquery">def first(function) |
||
return function() |
return function() |
||
end |
end |
||
Line 2,214: | Line 2,214: | ||
result = first(second) |
result = first(second) |
||
println result</ |
println result</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>second</pre> |
<pre>second</pre> |
||
Line 2,220: | Line 2,220: | ||
=={{header|Nemerle}}== |
=={{header|Nemerle}}== |
||
Functions must declare the types of their parameters in Nemerle. Function types in Nemerle are written ''params type'' -> ''return type'', as seen in the simple example below. |
Functions must declare the types of their parameters in Nemerle. Function types in Nemerle are written ''params type'' -> ''return type'', as seen in the simple example below. |
||
< |
<syntaxhighlight lang="nemerle">Twice[T] (f : T -> T, x : T) : T { f(f(x)) }</syntaxhighlight> |
||
=={{header|NewLISP}}== |
=={{header|NewLISP}}== |
||
< |
<syntaxhighlight lang="newlisp">> (define (my-multiply a b) (* a b)) |
||
(lambda (a b) (* a b)) |
(lambda (a b) (* a b)) |
||
> (define (call-it f x y) (f x y)) |
> (define (call-it f x y) (f x y)) |
||
Line 2,229: | Line 2,229: | ||
> (call-it my-multiply 2 3) |
> (call-it my-multiply 2 3) |
||
6 |
6 |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Nim}}== |
=={{header|Nim}}== |
||
< |
<syntaxhighlight lang="nim">proc first(fn: proc): auto = |
||
return fn() |
return fn() |
||
Line 2,238: | Line 2,238: | ||
return "second" |
return "second" |
||
echo first(second)</ |
echo first(second)</syntaxhighlight> |
||
=={{header|Oberon-2}}== |
=={{header|Oberon-2}}== |
||
Works with oo2c version 2 |
Works with oo2c version 2 |
||
< |
<syntaxhighlight lang="oberon2"> |
||
MODULE HOFuns; |
MODULE HOFuns; |
||
IMPORT |
IMPORT |
||
Line 2,277: | Line 2,277: | ||
PrintWords(words,Tools.AdjustRight) |
PrintWords(words,Tools.AdjustRight) |
||
END HOFuns. |
END HOFuns. |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Objeck}}== |
=={{header|Objeck}}== |
||
< |
<syntaxhighlight lang="objeck"> |
||
bundle Default { |
bundle Default { |
||
class HighOrder { |
class HighOrder { |
||
Line 2,297: | Line 2,297: | ||
} |
} |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|OCaml}}== |
=={{header|OCaml}}== |
||
A function is just a value that wants arguments: |
A function is just a value that wants arguments: |
||
< |
<syntaxhighlight lang="ocaml"># let func1 f = f "a string";; |
||
val func1 : (string -> 'a) -> 'a = <fun> |
val func1 : (string -> 'a) -> 'a = <fun> |
||
# let func2 s = "func2 called with " ^ s;; |
# let func2 s = "func2 called with " ^ s;; |
||
Line 2,309: | Line 2,309: | ||
# print_endline (func1 func2);; |
# print_endline (func1 func2);; |
||
func2 called with a string |
func2 called with a string |
||
- : unit = ()</ |
- : unit = ()</syntaxhighlight> |
||
Or, with an anonymous function: |
Or, with an anonymous function: |
||
< |
<syntaxhighlight lang="ocaml"># let func f = f 1 2;; |
||
val func : (int -> int -> 'a) -> 'a = <fun> |
val func : (int -> int -> 'a) -> 'a = <fun> |
||
# Printf.printf "%d\n" (func (fun x y -> x + y));; |
# Printf.printf "%d\n" (func (fun x y -> x + y));; |
||
3 |
3 |
||
- : unit = ()</ |
- : unit = ()</syntaxhighlight> |
||
Note that <tt>func (fun x y -> x + y)</tt> is equivalent to <tt>func (+)</tt>. (Operators are functions too.) |
Note that <tt>func (fun x y -> x + y)</tt> is equivalent to <tt>func (+)</tt>. (Operators are functions too.) |
||
Line 2,324: | Line 2,324: | ||
We can pass a function handle (<code>@function_name</code>) |
We can pass a function handle (<code>@function_name</code>) |
||
< |
<syntaxhighlight lang="octave">function r = computeit(f, g, v) |
||
r = f(g(v)); |
r = f(g(v)); |
||
endfunction |
endfunction |
||
computeit(@exp, @sin, pi/3) |
computeit(@exp, @sin, pi/3) |
||
computeit(@log, @cos, pi/6)</ |
computeit(@log, @cos, pi/6)</syntaxhighlight> |
||
Or pass the string name of the function and use the <code>feval</code> primitive. |
Or pass the string name of the function and use the <code>feval</code> primitive. |
||
< |
<syntaxhighlight lang="octave">function r = computeit2(f, g, v) |
||
r = f(feval(g, v)); |
r = f(feval(g, v)); |
||
endfunction |
endfunction |
||
computeit2(@exp, "sin", pi/3)</ |
computeit2(@exp, "sin", pi/3)</syntaxhighlight> |
||
=={{header|Oforth}}== |
=={{header|Oforth}}== |
||
Line 2,343: | Line 2,343: | ||
If you add # before a function or method name you push the function object on the stack (instead of performing the function). This allows to pass functions to other functions, as for any other object. |
If you add # before a function or method name you push the function object on the stack (instead of performing the function). This allows to pass functions to other functions, as for any other object. |
||
Here we pass #1+ to map : |
Here we pass #1+ to map : |
||
< |
<syntaxhighlight lang="oforth">[1, 2, 3, 4, 5 ] map(#1+)</syntaxhighlight> |
||
=={{header|Ol}}== |
=={{header|Ol}}== |
||
< |
<syntaxhighlight lang="scheme"> |
||
; typical use: |
; typical use: |
||
(for-each display '(1 2 "ss" '(3 4) 8)) |
(for-each display '(1 2 "ss" '(3 4) 8)) |
||
Line 2,356: | Line 2,356: | ||
(do print 12345) |
(do print 12345) |
||
; ==> 12345 |
; ==> 12345 |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|ooRexx}}== |
=={{header|ooRexx}}== |
||
routines are first class ooRexx objects that can be passed to other routines or methods and invoked. |
routines are first class ooRexx objects that can be passed to other routines or methods and invoked. |
||
< |
<syntaxhighlight lang="oorexx">say callit(.routines~fib, 10) |
||
say callit(.routines~fact, 6) |
say callit(.routines~fact, 6) |
||
say callit(.routines~square, 13) |
say callit(.routines~square, 13) |
||
Line 2,415: | Line 2,415: | ||
next = current |
next = current |
||
end |
end |
||
return current</ |
return current</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>55 |
<pre>55 |
||
Line 2,429: | Line 2,429: | ||
Functions in Order can accept any other named function, local variable, or anonymous function as arguments: |
Functions in Order can accept any other named function, local variable, or anonymous function as arguments: |
||
<syntaxhighlight lang="c"> |
|||
<lang C> |
|||
#include <order/interpreter.h> |
#include <order/interpreter.h> |
||
Line 2,458: | Line 2,458: | ||
) |
) |
||
// -> 16 |
// -> 16 |
||
</syntaxhighlight> |
|||
</lang> |
|||
The only difference between toplevel function definitions, and variables or literals, is that variables and anonymous functions must be called using the <code>8ap</code> syntactic form rather than direct argument application syntax. This is a limitation of the C preprocessor. |
The only difference between toplevel function definitions, and variables or literals, is that variables and anonymous functions must be called using the <code>8ap</code> syntactic form rather than direct argument application syntax. This is a limitation of the C preprocessor. |
||
=={{header|OxygenBasic}}== |
=={{header|OxygenBasic}}== |
||
< |
<syntaxhighlight lang="oxygenbasic"> |
||
'FUNCTION TO BE PASSED |
'FUNCTION TO BE PASSED |
||
'===================== |
'===================== |
||
Line 2,492: | Line 2,492: | ||
print g(@f#double#double) 'result '42' |
print g(@f#double#double) 'result '42' |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Oz}}== |
=={{header|Oz}}== |
||
Functions are just regular values in Oz. |
Functions are just regular values in Oz. |
||
< |
<syntaxhighlight lang="oz">declare |
||
fun {Twice Function X} |
fun {Twice Function X} |
||
{Function {Function X}} |
{Function {Function X}} |
||
end |
end |
||
in |
in |
||
{Show {Twice Sqrt 81.0}} %% prints 3.0</ |
{Show {Twice Sqrt 81.0}} %% prints 3.0</syntaxhighlight> |
||
=={{header|PARI/GP}}== |
=={{header|PARI/GP}}== |
||
{{works with|PARI/GP|2.4.2 and above}} <!-- requires closures --> |
{{works with|PARI/GP|2.4.2 and above}} <!-- requires closures --> |
||
< |
<syntaxhighlight lang="parigp">secant_root(ff,a,b)={ |
||
e = eps() * 2; |
e = eps() * 2; |
||
aval=ff(a); |
aval=ff(a); |
||
Line 2,523: | Line 2,523: | ||
precision(2. >> (32 * ceil(default(realprecision) * 38539962 / 371253907)), 9) |
precision(2. >> (32 * ceil(default(realprecision) * 38539962 / 371253907)), 9) |
||
}; |
}; |
||
addhelp(eps,"Returns machine epsilon for the current precision.");</ |
addhelp(eps,"Returns machine epsilon for the current precision.");</syntaxhighlight> |
||
=={{header|Pascal}}== |
=={{header|Pascal}}== |
||
Standard Pascal (will not work with Turbo Pascal): |
Standard Pascal (will not work with Turbo Pascal): |
||
< |
<syntaxhighlight lang="pascal">program example(output); |
||
function first(function f(x: real): real): real; |
function first(function f(x: real): real): real; |
||
Line 2,541: | Line 2,541: | ||
begin |
begin |
||
writeln(first(second)); |
writeln(first(second)); |
||
end.</ |
end.</syntaxhighlight> |
||
[[Turbo Pascal]] (will not work with Standard Pascal): |
[[Turbo Pascal]] (will not work with Standard Pascal): |
||
< |
<syntaxhighlight lang="pascal">program example; |
||
type |
type |
||
Line 2,564: | Line 2,564: | ||
begin |
begin |
||
writeln(first(second)); |
writeln(first(second)); |
||
end.</ |
end.</syntaxhighlight> |
||
=== using FreePascal : Higher-order function MAP / REDUCE ( FOLDL / FOLDR ) / FILTER === |
=== using FreePascal : Higher-order function MAP / REDUCE ( FOLDL / FOLDR ) / FILTER === |
||
{{works with|Free Pascal|3.2.0 }} |
{{works with|Free Pascal|3.2.0 }} |
||
<syntaxhighlight lang="pascal"> |
|||
<lang Pascal> |
|||
UNIT MRF; |
UNIT MRF; |
||
{$mode Delphi} {$H+} {$J-} {$R+} (*) https://www.freepascal.org/docs-html/prog/progch1.html (*) |
{$mode Delphi} {$H+} {$J-} {$R+} (*) https://www.freepascal.org/docs-html/prog/progch1.html (*) |
||
Line 3,291: | Line 3,291: | ||
</ |
</syntaxhighlight>JPD 2021/07/10 |
||
Output: |
Output: |
||
Line 3,298: | Line 3,298: | ||
=={{header|Perl}}== |
=={{header|Perl}}== |
||
< |
<syntaxhighlight lang="perl">sub another { |
||
# take a function and a value |
# take a function and a value |
||
my $func = shift; |
my $func = shift; |
||
Line 3,324: | Line 3,324: | ||
); |
); |
||
print another $dispatch{$_}, 123 for qw(square cube rev);</ |
print another $dispatch{$_}, 123 for qw(square cube rev);</syntaxhighlight> |
||
< |
<syntaxhighlight lang="perl">sub apply (&@) { # use & as the first item in a prototype to take bare blocks like map and grep |
||
my ($sub, @ret) = @_; # this function applies a function that is expected to modify $_ to a list |
my ($sub, @ret) = @_; # this function applies a function that is expected to modify $_ to a list |
||
$sub->() for @ret; # it allows for simple inline application of the s/// and tr/// constructs |
$sub->() for @ret; # it allows for simple inline application of the s/// and tr/// constructs |
||
Line 3,333: | Line 3,333: | ||
print join ", " => apply {tr/aeiou/AEIOU/} qw/one two three four/; |
print join ", " => apply {tr/aeiou/AEIOU/} qw/one two three four/; |
||
# OnE, twO, thrEE, fOUr</ |
# OnE, twO, thrEE, fOUr</syntaxhighlight> |
||
< |
<syntaxhighlight lang="perl">sub first {shift->()} |
||
sub second {'second'} |
sub second {'second'} |
||
Line 3,341: | Line 3,341: | ||
print first \&second; |
print first \&second; |
||
print first sub{'sub'};</ |
print first sub{'sub'};</syntaxhighlight> |
||
=={{header|Phix}}== |
=={{header|Phix}}== |
||
{{libheader|Phix/basics}} |
{{libheader|Phix/basics}} |
||
<!--< |
<!--<syntaxhighlight lang="phix">(phixonline)--> |
||
<span style="color: #008080;">procedure</span> <span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">fi</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> |
<span style="color: #008080;">procedure</span> <span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">fi</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> |
||
<span style="color: #0000FF;">?</span><span style="color: #000000;">fi</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> |
<span style="color: #0000FF;">?</span><span style="color: #000000;">fi</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> |
||
Line 3,355: | Line 3,355: | ||
<span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #000000;">add</span><span style="color: #0000FF;">,</span><span style="color: #000000;">23</span><span style="color: #0000FF;">,</span><span style="color: #000000;">45</span><span style="color: #0000FF;">)</span> |
<span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #000000;">add</span><span style="color: #0000FF;">,</span><span style="color: #000000;">23</span><span style="color: #0000FF;">,</span><span style="color: #000000;">45</span><span style="color: #0000FF;">)</span> |
||
<!--</ |
<!--</syntaxhighlight>--> |
||
{{out}} |
{{out}} |
||
<pre> |
<pre> |
||
Line 3,364: | Line 3,364: | ||
The plain add, without a trailing '(' to make it a direct invocation, resolves to a symbol table index.<br> |
The plain add, without a trailing '(' to make it a direct invocation, resolves to a symbol table index.<br> |
||
Obviously you can use (an otherwise pointless) user defined type (of any name you like) instead of integer if preferred, eg |
Obviously you can use (an otherwise pointless) user defined type (of any name you like) instead of integer if preferred, eg |
||
<!--< |
<!--<syntaxhighlight lang="phix">--> |
||
<span style="color: #008080;">type</span> <span style="color: #000000;">rid</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000080;font-style:italic;">/*r*/</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #004600;">true</span> <span style="color: #008080;">end</span> <span style="color: #008080;">type</span> |
<span style="color: #008080;">type</span> <span style="color: #000000;">rid</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000080;font-style:italic;">/*r*/</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #004600;">true</span> <span style="color: #008080;">end</span> <span style="color: #008080;">type</span> |
||
<span style="color: #008080;">procedure</span> <span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #000000;">rid</span> <span style="color: #000000;">fi</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)...</span> |
<span style="color: #008080;">procedure</span> <span style="color: #000000;">use</span><span style="color: #0000FF;">(</span><span style="color: #000000;">rid</span> <span style="color: #000000;">fi</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)...</span> |
||
<!--</ |
<!--</syntaxhighlight>--> |
||
=={{header|Phixmonti}}== |
=={{header|Phixmonti}}== |
||
< |
<syntaxhighlight lang="phixmonti">def suma + enddef |
||
def apply exec enddef |
def apply exec enddef |
||
23 45 getid suma apply print |
23 45 getid suma apply print |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|PHP}}== |
=={{header|PHP}}== |
||
< |
<syntaxhighlight lang="php">function first($func) { |
||
return $func(); |
return $func(); |
||
} |
} |
||
Line 3,387: | Line 3,387: | ||
} |
} |
||
$result = first('second');</ |
$result = first('second');</syntaxhighlight> |
||
Or, with an anonymous function in PHP 5.3+: |
Or, with an anonymous function in PHP 5.3+: |
||
< |
<syntaxhighlight lang="php">function first($func) { |
||
return $func(); |
return $func(); |
||
} |
} |
||
$result = first(function() { return 'second'; });</ |
$result = first(function() { return 'second'; });</syntaxhighlight> |
||
=={{header|Picat}}== |
=={{header|Picat}}== |
||
Here are some different approaches. |
Here are some different approaches. |
||
The following variables and functions are assumed to be defined: |
The following variables and functions are assumed to be defined: |
||
< |
<syntaxhighlight lang="picat">go => |
||
% ... |
% ... |
||
L = 1..10, |
L = 1..10, |
||
Line 3,418: | Line 3,418: | ||
% sort on length |
% sort on length |
||
sortf(F1,F2) => |
sortf(F1,F2) => |
||
F1.length < F2.length.</ |
F1.length < F2.length.</syntaxhighlight> |
||
===Using map=== |
===Using map=== |
||
< |
<syntaxhighlight lang="picat"> % ... |
||
println(map(f1,L)), |
println(map(f1,L)), |
||
println(map($f2(3),L)), |
println(map($f2(3),L)), |
||
println(map(f2,L,map(f1,L))).</ |
println(map(f2,L,map(f1,L))).</syntaxhighlight> |
||
===List comprehension=== |
===List comprehension=== |
||
In general the recommended approach. |
In general the recommended approach. |
||
<syntaxhighlight lang="picat"> % |
|||
<lang Picat> % |
|||
println([f1(I) : I in L]), |
println([f1(I) : I in L]), |
||
println([[I,J,f2(I,J)] : I in L, J in L2]).</ |
println([[I,J,f2(I,J)] : I in L, J in L2]).</syntaxhighlight> |
||
===Apply=== |
===Apply=== |
||
< |
<syntaxhighlight lang="picat"> % ... |
||
println(apply(+,1,2)), |
println(apply(+,1,2)), |
||
println(apply(f2,10,22)).</ |
println(apply(f2,10,22)).</syntaxhighlight> |
||
===Sort function=== |
===Sort function=== |
||
Here is an example how to sort on length. |
Here is an example how to sort on length. |
||
< |
<syntaxhighlight lang="picat"> % ... |
||
S = [ |
S = [ |
||
"rosetta code", |
"rosetta code", |
||
Line 3,452: | Line 3,452: | ||
], |
], |
||
println(map(len,S)), |
println(map(len,S)), |
||
println(S.qsort(sortf)).</ |
println(S.qsort(sortf)).</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 3,466: | Line 3,466: | ||
=={{header|PicoLisp}}== |
=={{header|PicoLisp}}== |
||
< |
<syntaxhighlight lang="picolisp">: (de first (Fun) |
||
(Fun) ) |
(Fun) ) |
||
-> first |
-> first |
||
Line 3,498: | Line 3,498: | ||
: (mapcar add (1 2 3) (4 5 6)) |
: (mapcar add (1 2 3) (4 5 6)) |
||
-> (5 7 9)</ |
-> (5 7 9)</syntaxhighlight> |
||
=={{header|PL/I}}== |
=={{header|PL/I}}== |
||
<syntaxhighlight lang="pl/i"> |
|||
<lang PL/I> |
|||
f: procedure (g) returns (float); |
f: procedure (g) returns (float); |
||
declare g entry (float); |
declare g entry (float); |
||
Line 3,510: | Line 3,510: | ||
x = f(p); /* where "p" is the name of a function. */ |
x = f(p); /* where "p" is the name of a function. */ |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Pop11}}== |
=={{header|Pop11}}== |
||
< |
<syntaxhighlight lang="pop11">;;; Define a function |
||
define x_times_three_minus_1(x); |
define x_times_three_minus_1(x); |
||
return(3*x-1); |
return(3*x-1); |
||
Line 3,519: | Line 3,519: | ||
;;; Pass it as argument to built-in function map and print the result |
;;; Pass it as argument to built-in function map and print the result |
||
mapdata({0 1 2 3 4}, x_times_three_minus_1) =></ |
mapdata({0 1 2 3 4}, x_times_three_minus_1) =></syntaxhighlight> |
||
=={{header|PostScript}}== |
=={{header|PostScript}}== |
||
Postscript functions are either built-in operators or executable arrays (procedures). Both can take either as arguments. |
Postscript functions are either built-in operators or executable arrays (procedures). Both can take either as arguments. |
||
<lang> |
<syntaxhighlight lang="text"> |
||
% operator example |
% operator example |
||
% 'ifelse' is passed a boolean and two procedures |
% 'ifelse' is passed a boolean and two procedures |
||
Line 3,534: | Line 3,534: | ||
/bar { (Hello, world!) } def |
/bar { (Hello, world!) } def |
||
/bar load foo == |
/bar load foo == |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|PowerShell}}== |
=={{header|PowerShell}}== |
||
{{works with|PowerShell|4.0}} |
{{works with|PowerShell|4.0}} |
||
<syntaxhighlight lang="powershell"> |
|||
<lang PowerShell> |
|||
function f ($y) { |
function f ($y) { |
||
$y*$y |
$y*$y |
||
Line 3,545: | Line 3,545: | ||
(f $y) |
(f $y) |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
You can implement a function inside a function. |
You can implement a function inside a function. |
||
<syntaxhighlight lang="powershell"> |
|||
<lang PowerShell> |
|||
function g2($y) { |
function g2($y) { |
||
function f2($y) { |
function f2($y) { |
||
Line 3,556: | Line 3,556: | ||
(f2 $y) |
(f2 $y) |
||
} |
} |
||
</syntaxhighlight> |
|||
</lang> |
|||
<b>Calling:</b> |
<b>Calling:</b> |
||
<syntaxhighlight lang="powershell"> |
|||
<lang PowerShell> |
|||
g f 5 |
g f 5 |
||
g2 9 |
g2 9 |
||
</syntaxhighlight> |
|||
</lang> |
|||
<b>Output:</b> |
<b>Output:</b> |
||
<pre> |
<pre> |
||
Line 3,569: | Line 3,569: | ||
=={{header|Prolog}}== |
=={{header|Prolog}}== |
||
< |
<syntaxhighlight lang="prolog"> |
||
first(Predicate) :- call(Predicate). |
first(Predicate) :- call(Predicate). |
||
second(Argument) :- write(Argument). |
second(Argument) :- write(Argument). |
||
:-first(second('Hello World!')). |
:-first(second('Hello World!')). |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|PureBasic}}== |
=={{header|PureBasic}}== |
||
< |
<syntaxhighlight lang="purebasic">Prototype.d func(*text$) |
||
Procedure NumberTwo(arg$) |
Procedure NumberTwo(arg$) |
||
Line 3,588: | Line 3,588: | ||
EndProcedure |
EndProcedure |
||
NumberOne(@NumberTwo(),"Hello Worldy!")</ |
NumberOne(@NumberTwo(),"Hello Worldy!")</syntaxhighlight> |
||
=={{header|Python}}== |
=={{header|Python}}== |
||
{{works with|Python|2.5}} |
{{works with|Python|2.5}} |
||
< |
<syntaxhighlight lang="python">def first(function): |
||
return function() |
return function() |
||
Line 3,599: | Line 3,599: | ||
return "second" |
return "second" |
||
result = first(second)</ |
result = first(second)</syntaxhighlight> |
||
or |
or |
||
< |
<syntaxhighlight lang="python"> result = first(lambda: "second")</syntaxhighlight> |
||
Functions are first class objects in Python. They can be bound to names ("assigned" to "variables"), associated with keys in dictionaries, and passed around like any other object. |
Functions are first class objects in Python. They can be bound to names ("assigned" to "variables"), associated with keys in dictionaries, and passed around like any other object. |
||
Line 3,611: | Line 3,611: | ||
Its helpful to remember that in Q, when parameters aren't named in the function declaration, <tt>x</tt> is assumed to be the first parameter. |
Its helpful to remember that in Q, when parameters aren't named in the function declaration, <tt>x</tt> is assumed to be the first parameter. |
||
<syntaxhighlight lang="q"> |
|||
<lang Q> |
|||
q)sayHi:{-1"Hello ",x;} |
q)sayHi:{-1"Hello ",x;} |
||
q)callFuncWithParam:{x["Peter"]} |
q)callFuncWithParam:{x["Peter"]} |
||
Line 3,617: | Line 3,617: | ||
Hello Peter |
Hello Peter |
||
q)callFuncWithParam[sayHi] |
q)callFuncWithParam[sayHi] |
||
Hello Peter</ |
Hello Peter</syntaxhighlight> |
||
=={{header|Quackery}}== |
=={{header|Quackery}}== |
||
Line 3,682: | Line 3,682: | ||
=={{header|R}}== |
=={{header|R}}== |
||
< |
<syntaxhighlight lang="r">f <- function(f0) f0(pi) # calc. the function in pi |
||
tf <- function(x) x^pi # a func. just to test |
tf <- function(x) x^pi # a func. just to test |
||
print(f(sin)) |
print(f(sin)) |
||
print(f(cos)) |
print(f(cos)) |
||
print(f(tf))</ |
print(f(tf))</syntaxhighlight> |
||
=={{header|Racket}}== |
=={{header|Racket}}== |
||
<syntaxhighlight lang="racket"> |
|||
<lang Racket> |
|||
#lang racket/base |
#lang racket/base |
||
(define (add f g x) |
(define (add f g x) |
||
(+ (f x) (g x))) |
(+ (f x) (g x))) |
||
(add sin cos 10) |
(add sin cos 10) |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Raku}}== |
=={{header|Raku}}== |
||
Line 3,705: | Line 3,705: | ||
either a bare block, or a parametrized block introduced with <tt>-></tt>, which serves as a "lambda": |
either a bare block, or a parametrized block introduced with <tt>-></tt>, which serves as a "lambda": |
||
<lang |
<syntaxhighlight lang="raku" line>sub twice(&todo) { |
||
todo(); todo(); # declaring &todo also defines bare function |
todo(); todo(); # declaring &todo also defines bare function |
||
} |
} |
||
Line 3,721: | Line 3,721: | ||
# output: |
# output: |
||
# 1: Hello! |
# 1: Hello! |
||
# 2: Hello!</ |
# 2: Hello!</syntaxhighlight> |
||
=={{header|Raven}}== |
=={{header|Raven}}== |
||
This is not strictly passing a function, but the string representing the function name. |
This is not strictly passing a function, but the string representing the function name. |
||
< |
<syntaxhighlight lang="raven">define doit use $v1 |
||
"doit called with " print $v1 print "\n" print |
"doit called with " print $v1 print "\n" print |
||
Line 3,732: | Line 3,732: | ||
$v2 call |
$v2 call |
||
23.54 "doit" callit</ |
23.54 "doit" callit</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>callit called with doit |
<pre>callit called with doit |
||
Line 3,739: | Line 3,739: | ||
=={{header|REBOL}}== |
=={{header|REBOL}}== |
||
< |
<syntaxhighlight lang="rebol">REBOL [ |
||
Title: "Function Argument" |
Title: "Function Argument" |
||
URL: http://rosettacode.org/wiki/Function_as_an_Argument |
URL: http://rosettacode.org/wiki/Function_as_an_Argument |
||
Line 3,768: | Line 3,768: | ||
print ["Squared:" mold map :square x] |
print ["Squared:" mold map :square x] |
||
print ["Cubed: " mold map :cube x] |
print ["Cubed: " mold map :cube x] |
||
print ["Unnamed:" mold map func [i][i * 2 + 1] x]</ |
print ["Unnamed:" mold map func [i][i * 2 + 1] x]</syntaxhighlight> |
||
Output: |
Output: |
||
Line 3,778: | Line 3,778: | ||
=={{header|Retro}}== |
=={{header|Retro}}== |
||
< |
<syntaxhighlight lang="retro">:disp (nq-) call n:put ; |
||
#31 [ (n-n) #100 * ] disp |
#31 [ (n-n) #100 * ] disp |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|REXX}}== |
=={{header|REXX}}== |
||
< |
<syntaxhighlight lang="rexx">/*REXX program demonstrates the passing of a name of a function to another function. */ |
||
call function 'fact' , 6; say right( 'fact{'$"} = ", 30) result |
call function 'fact' , 6; say right( 'fact{'$"} = ", 30) result |
||
call function 'square' , 13; say right( 'square{'$"} = ", 30) result |
call function 'square' , 13; say right( 'square{'$"} = ", 30) result |
||
Line 3,795: | Line 3,795: | ||
function: arg ?.; parse arg ,$; signal value (?.) |
function: arg ?.; parse arg ,$; signal value (?.) |
||
reverse: return 'REVERSE'($) |
reverse: return 'REVERSE'($) |
||
square: return $**2</ |
square: return $**2</syntaxhighlight> |
||
{{out|output|text= when using the default input:}} |
{{out|output|text= when using the default input:}} |
||
<pre> |
<pre> |
||
Line 3,805: | Line 3,805: | ||
=={{header|Ring}}== |
=={{header|Ring}}== |
||
< |
<syntaxhighlight lang="ring"> |
||
# Project : Higher-order functions |
# Project : Higher-order functions |
||
Line 3,824: | Line 3,824: | ||
next |
next |
||
see nl |
see nl |
||
</syntaxhighlight> |
|||
</lang> |
|||
Output: |
Output: |
||
<pre> |
<pre> |
||
Line 3,854: | Line 3,854: | ||
=={{header|Ruby}}== |
=={{header|Ruby}}== |
||
With a proc (procedure): |
With a proc (procedure): |
||
< |
<syntaxhighlight lang="ruby">succ = proc{|x| x+1} |
||
def to2(&f) |
def to2(&f) |
||
f[2] |
f[2] |
||
Line 3,860: | Line 3,860: | ||
to2(&succ) #=> 3 |
to2(&succ) #=> 3 |
||
to2{|x| x+1} #=> 3</ |
to2{|x| x+1} #=> 3</syntaxhighlight> |
||
With a method: |
With a method: |
||
< |
<syntaxhighlight lang="ruby">def succ(n) |
||
n+1 |
n+1 |
||
end |
end |
||
Line 3,871: | Line 3,871: | ||
meth = method(:succ) |
meth = method(:succ) |
||
to2(meth) #=> 3</ |
to2(meth) #=> 3</syntaxhighlight> |
||
=={{header|Rust}}== |
=={{header|Rust}}== |
||
Functions are first class values and identified in the type system by implementing the FnOnce, FnMut or the Fn trait which happens implicitly for functions and closures. |
Functions are first class values and identified in the type system by implementing the FnOnce, FnMut or the Fn trait which happens implicitly for functions and closures. |
||
< |
<syntaxhighlight lang="rust">fn execute_with_10<F: Fn(u64) -> u64> (f: F) -> u64 { |
||
f(10) |
f(10) |
||
} |
} |
||
Line 3,886: | Line 3,886: | ||
println!("{}", execute_with_10(|n| n*n )); // closure |
println!("{}", execute_with_10(|n| n*n )); // closure |
||
println!("{}", execute_with_10(square)); // function |
println!("{}", execute_with_10(square)); // function |
||
}</ |
}</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>100 |
<pre>100 |
||
Line 3,892: | Line 3,892: | ||
=={{header|Scala}}== |
=={{header|Scala}}== |
||
< |
<syntaxhighlight lang="scala">def functionWithAFunctionArgument(x : int, y : int, f : (int, int) => int) = f(x,y)</syntaxhighlight> |
||
Call: |
Call: |
||
< |
<syntaxhighlight lang="scala">functionWithAFunctionArgument(3, 5, {(x, y) => x + y}) // returns 8</syntaxhighlight> |
||
=={{header|Scheme}}== |
=={{header|Scheme}}== |
||
A function is just a value that wants arguments: |
A function is just a value that wants arguments: |
||
< |
<syntaxhighlight lang="scheme">> (define (func1 f) (f "a string")) |
||
> (define (func2 s) (string-append "func2 called with " s)) |
> (define (func2 s) (string-append "func2 called with " s)) |
||
> (begin (display (func1 func2)) (newline)) |
> (begin (display (func1 func2)) (newline)) |
||
func2 called with a string</ |
func2 called with a string</syntaxhighlight> |
||
Or, with an anonymous function: |
Or, with an anonymous function: |
||
< |
<syntaxhighlight lang="scheme">> (define (func f) (f 1 2)) |
||
> (begin (display (func (lambda (x y) (+ x y)))) (newline)) |
> (begin (display (func (lambda (x y) (+ x y)))) (newline)) |
||
3</ |
3</syntaxhighlight> |
||
Note that <tt>(func (lambda (x y) (+ x y)))</tt> is equivalent to <tt>(func +)</tt>. (Operators are functions too.) |
Note that <tt>(func (lambda (x y) (+ x y)))</tt> is equivalent to <tt>(func +)</tt>. (Operators are functions too.) |
||
=={{header|SenseTalk}}== |
=={{header|SenseTalk}}== |
||
< |
<syntaxhighlight lang="sensetalk">function Map oldlist, func |
||
put () into newlist |
put () into newlist |
||
repeat with each item of oldlist |
repeat with each item of oldlist |
||
Line 3,917: | Line 3,917: | ||
end repeat |
end repeat |
||
return newlist |
return newlist |
||
end Map</ |
end Map</syntaxhighlight> |
||
< |
<syntaxhighlight lang="sensetalk">put ("tomato", "aubergine", "courgette") into fruits |
||
put Map(fruits, Uppercase) |
put Map(fruits, Uppercase) |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Sidef}}== |
=={{header|Sidef}}== |
||
< |
<syntaxhighlight lang="ruby">func first(f) { |
||
return f(); |
return f(); |
||
} |
} |
||
Line 3,933: | Line 3,933: | ||
say first(second); # => "second" |
say first(second); # => "second" |
||
say first(func { "third" }); # => "third"</ |
say first(func { "third" }); # => "third"</syntaxhighlight> |
||
=={{header|Slate}}== |
=={{header|Slate}}== |
||
Methods and blocks can both be passed as arguments to functions (other methods and blocks): |
Methods and blocks can both be passed as arguments to functions (other methods and blocks): |
||
< |
<syntaxhighlight lang="slate">define: #function -> [| :x | x * 3 - 1]. |
||
#(1 1 2 3 5 8) collect: function.</ |
#(1 1 2 3 5 8) collect: function.</syntaxhighlight> |
||
=={{header|Smalltalk}}== |
=={{header|Smalltalk}}== |
||
< |
<syntaxhighlight lang="smalltalk">first := [ :f | f value ]. |
||
second := [ 'second' ]. |
second := [ 'second' ]. |
||
Transcript show: (first value: second).</ |
Transcript show: (first value: second).</syntaxhighlight> |
||
< |
<syntaxhighlight lang="smalltalk">function := [:x | x * 3 - 1]. |
||
#(1 1 2 3 5 8) collect: function.</ |
#(1 1 2 3 5 8) collect: function.</syntaxhighlight> |
||
=={{header|Sparkling}}== |
=={{header|Sparkling}}== |
||
< |
<syntaxhighlight lang="sparkling">function call_me(func, arg) { |
||
return func(arg); |
return func(arg); |
||
} |
} |
||
let answer = call_me(function(x) { return 6 * x; }, 7); |
let answer = call_me(function(x) { return 6 * x; }, 7); |
||
print(answer);</ |
print(answer);</syntaxhighlight> |
||
=={{header|Standard ML}}== |
=={{header|Standard ML}}== |
||
< |
<syntaxhighlight lang="sml">- fun func1 f = f "a string"; |
||
val func1 = fn : (string -> 'a) -> 'a |
val func1 = fn : (string -> 'a) -> 'a |
||
- fun func2 s = "func2 called with " ^ s; |
- fun func2 s = "func2 called with " ^ s; |
||
Line 3,965: | Line 3,965: | ||
- print (func1 func2 ^ "\n"); |
- print (func1 func2 ^ "\n"); |
||
func2 called with a string |
func2 called with a string |
||
val it = () : unit</ |
val it = () : unit</syntaxhighlight> |
||
Or, with an anonymous function: |
Or, with an anonymous function: |
||
< |
<syntaxhighlight lang="sml">- fun func f = f (1, 2); |
||
val func = fn : (int * int -> 'a) -> 'a |
val func = fn : (int * int -> 'a) -> 'a |
||
- print (Int.toString (func (fn (x, y) => x + y)) ^ "\n"); |
- print (Int.toString (func (fn (x, y) => x + y)) ^ "\n"); |
||
3 |
3 |
||
val it = () : unit</ |
val it = () : unit</syntaxhighlight> |
||
Note that <tt>func (fn (x, y) => x + y)</tt> is equivalent to <tt>func op+</tt>. (Operators are functions too.) |
Note that <tt>func (fn (x, y) => x + y)</tt> is equivalent to <tt>func op+</tt>. (Operators are functions too.) |
||
=={{header|SuperCollider}}== |
=={{header|SuperCollider}}== |
||
< |
<syntaxhighlight lang="supercollider">f = { |x, y| x.(y) }; // a function that takes a function and calls it with an argument |
||
f.({ |x| x + 1 }, 5); // returns 5</ |
f.({ |x| x + 1 }, 5); // returns 5</syntaxhighlight> |
||
=={{header|Swift}}== |
=={{header|Swift}}== |
||
< |
<syntaxhighlight lang="swift">func func1(f: String->String) -> String { return f("a string") } |
||
func func2(s: String) -> String { return "func2 called with " + s } |
func func2(s: String) -> String { return "func2 called with " + s } |
||
println(func1(func2)) // prints "func2 called with a string"</ |
println(func1(func2)) // prints "func2 called with a string"</syntaxhighlight> |
||
Or, with an anonymous function: |
Or, with an anonymous function: |
||
< |
<syntaxhighlight lang="swift">func func3<T>(f: (Int,Int)->T) -> T { return f(1, 2) } |
||
println(func3 {(x, y) in x + y}) // prints "3"</ |
println(func3 {(x, y) in x + y}) // prints "3"</syntaxhighlight> |
||
Note that <tt>{(x, y) in x + y}</tt> can also be written as <tt>{$0 + $1}</tt> or just <tt>+</tt>. |
Note that <tt>{(x, y) in x + y}</tt> can also be written as <tt>{$0 + $1}</tt> or just <tt>+</tt>. |
||
=={{header|Tcl}}== |
=={{header|Tcl}}== |
||
< |
<syntaxhighlight lang="tcl"># this procedure executes its argument: |
||
proc demo {function} { |
proc demo {function} { |
||
$function |
$function |
||
} |
} |
||
# for example: |
# for example: |
||
demo bell</ |
demo bell</syntaxhighlight> |
||
It is more common to pass not just a function, but a command fragment or entire script. When used with the built-in <tt>list</tt> command (which introduces a very useful degree of quoting) this makes for a very common set of techniques when doing advanced Tcl programming. |
It is more common to pass not just a function, but a command fragment or entire script. When used with the built-in <tt>list</tt> command (which introduces a very useful degree of quoting) this makes for a very common set of techniques when doing advanced Tcl programming. |
||
< |
<syntaxhighlight lang="tcl"># This procedure executes its argument with an extra argument of "2" |
||
proc demoFrag {fragment} { |
proc demoFrag {fragment} { |
||
{*}$fragment 2 |
{*}$fragment 2 |
||
Line 4,016: | Line 4,016: | ||
demoScript { |
demoScript { |
||
parray tcl_platform |
parray tcl_platform |
||
}</ |
}</syntaxhighlight> |
||
=={{header|TI-89 BASIC}}== |
=={{header|TI-89 BASIC}}== |
||
Line 4,024: | Line 4,024: | ||
The function name passed cannot be that of a local function, because the local function <code>map</code> does not see the local variables of the enclosing function. |
The function name passed cannot be that of a local function, because the local function <code>map</code> does not see the local variables of the enclosing function. |
||
< |
<syntaxhighlight lang="ti89b">Local map |
||
Define map(f,l)=Func |
Define map(f,l)=Func |
||
Return seq(#f(l[i]),i,1,dim(l)) |
Return seq(#f(l[i]),i,1,dim(l)) |
||
EndFunc |
EndFunc |
||
Disp map("sin", {0, π/6, π/4, π/3, π/2})</ |
Disp map("sin", {0, π/6, π/4, π/3, π/2})</syntaxhighlight> |
||
=={{header|Toka}}== |
=={{header|Toka}}== |
||
Toka allows obtaining a function pointer via the '''`''' (''backtick'') word. The pointers are passed on the stack, just like all other data. |
Toka allows obtaining a function pointer via the '''`''' (''backtick'') word. The pointers are passed on the stack, just like all other data. |
||
< |
<syntaxhighlight lang="toka">[ ." First\n" ] is first |
||
[ invoke ] is second |
[ invoke ] is second |
||
` first second</ |
` first second</syntaxhighlight> |
||
=={{header|Trith}}== |
=={{header|Trith}}== |
||
Due to the homoiconic program representation and the [[concatenative]] nature of the language, higher-order functions are as simple as: |
Due to the homoiconic program representation and the [[concatenative]] nature of the language, higher-order functions are as simple as: |
||
< |
<syntaxhighlight lang="trith">: twice 2 times ; |
||
: hello "Hello, world!" print ; |
: hello "Hello, world!" print ; |
||
[hello] twice</ |
[hello] twice</syntaxhighlight> |
||
=={{header|TXR}}== |
=={{header|TXR}}== |
||
Line 4,047: | Line 4,047: | ||
<code>lambda</code> passed to <code>mapcar</code> with environment capture: |
<code>lambda</code> passed to <code>mapcar</code> with environment capture: |
||
< |
<syntaxhighlight lang="txr">@(bind a @(let ((counter 0)) |
||
(mapcar (lambda (x y) (list (inc counter) x y)) |
(mapcar (lambda (x y) (list (inc counter) x y)) |
||
'(a b c) '(t r s)))) |
'(a b c) '(t r s)))) |
||
Line 4,054: | Line 4,054: | ||
@ (rep)@a:@(last)@a@(end) |
@ (rep)@a:@(last)@a@(end) |
||
@ (end) |
@ (end) |
||
@(end)</ |
@(end)</syntaxhighlight> |
||
<pre>1:a:t |
<pre>1:a:t |
||
Line 4,062: | Line 4,062: | ||
=={{header|uBasic/4tH}}== |
=={{header|uBasic/4tH}}== |
||
{{trans|BBC BASIC}} |
{{trans|BBC BASIC}} |
||
<lang>' Test passing a function to a function: |
<syntaxhighlight lang="text">' Test passing a function to a function: |
||
Print FUNC(_FNtwo(_FNone, 10, 11)) |
Print FUNC(_FNtwo(_FNone, 10, 11)) |
||
End |
End |
||
Line 4,070: | Line 4,070: | ||
' Function taking a function as an argument: |
' Function taking a function as an argument: |
||
_FNtwo Param (3) : Return (FUNC(a@ (b@, c@)))</ |
_FNtwo Param (3) : Return (FUNC(a@ (b@, c@)))</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre>441 |
<pre>441 |
||
Line 4,078: | Line 4,078: | ||
{{trans|Python}} |
{{trans|Python}} |
||
Functions are first-class objects in Ursa. |
Functions are first-class objects in Ursa. |
||
< |
<syntaxhighlight lang="ursa">def first (function f) |
||
return (f) |
return (f) |
||
end |
end |
||
Line 4,087: | Line 4,087: | ||
out (first second) endl console |
out (first second) endl console |
||
# "second" is output to the console</ |
# "second" is output to the console</syntaxhighlight> |
||
=={{header|Ursala}}== |
=={{header|Ursala}}== |
||
Line 4,095: | Line 4,095: | ||
equivalent to the given functon composed with itself. |
equivalent to the given functon composed with itself. |
||
< |
<syntaxhighlight lang="ursala">(autocomposition "f") "x" = "f" "f" "x"</syntaxhighlight> |
||
test program: |
test program: |
||
< |
<syntaxhighlight lang="ursala">#import flo |
||
#cast %e |
#cast %e |
||
example = autocomposition(sqrt) 16.0</ |
example = autocomposition(sqrt) 16.0</syntaxhighlight> |
||
output: |
output: |
||
<pre>2.000000e+00</pre> |
<pre>2.000000e+00</pre> |
||
Line 4,106: | Line 4,106: | ||
=={{header|V}}== |
=={{header|V}}== |
||
Define first as multiplying two numbers on stack |
Define first as multiplying two numbers on stack |
||
<lang |
<syntaxhighlight lang="v">[first *].</syntaxhighlight> |
||
Define second as applying the passed quote on stack |
Define second as applying the passed quote on stack |
||
<lang |
<syntaxhighlight lang="v">[second i].</syntaxhighlight> |
||
Pass the first enclosed in quote to second which applies it on stack. |
Pass the first enclosed in quote to second which applies it on stack. |
||
<lang |
<syntaxhighlight lang="v">2 3 [first] second</syntaxhighlight> |
||
=6 |
=6 |
||
=={{header|VBA}}== |
=={{header|VBA}}== |
||
Based on the Pascal solution |
Based on the Pascal solution |
||
< |
<syntaxhighlight lang="pascal">Sub HigherOrder() |
||
Dim result As Single |
Dim result As Single |
||
result = first("second") |
result = first("second") |
||
Line 4,125: | Line 4,125: | ||
Function second(x As Single) As Single |
Function second(x As Single) As Single |
||
second = x / 2 |
second = x / 2 |
||
End Function</ |
End Function</syntaxhighlight> |
||
=={{header|Visual Basic .NET}}== |
=={{header|Visual Basic .NET}}== |
||
Line 4,139: | Line 4,139: | ||
===Named methods=== |
===Named methods=== |
||
{{trans|C#: Named methods}} |
{{trans|C#: Named methods}} |
||
< |
<syntaxhighlight lang="vbnet">' Delegate declaration is similar to C#. |
||
Delegate Function Func2(a As Integer, b As Integer) As Integer |
Delegate Function Func2(a As Integer, b As Integer) As Integer |
||
Line 4,177: | Line 4,177: | ||
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, [Call](div, a, b)) |
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, [Call](div, a, b)) |
||
End Sub |
End Sub |
||
End Module</ |
End Module</syntaxhighlight> |
||
===Lambda expressions=== |
===Lambda expressions=== |
||
{{trans|C#: Lambda expressions}} |
{{trans|C#: Lambda expressions}} |
||
Lambda expressions in VB.NET are similar to those in C#, except they can also explicitly specify a return type and exist as standalone "anonymous delegates". An anonymous delegate is created when a lambda expression is assigned to an implicitly typed variable (in which case the variable receives the type of the anonymous delegate) or when the target type given by context (at compile-time) is MulticastDelegate, Delegate, or Object. Anonymous delegates are derived from MulticastDelegate and are implicitly convertible to all compatible delegate types. A formal definition of delegate compatibility can be found in the language specification. |
Lambda expressions in VB.NET are similar to those in C#, except they can also explicitly specify a return type and exist as standalone "anonymous delegates". An anonymous delegate is created when a lambda expression is assigned to an implicitly typed variable (in which case the variable receives the type of the anonymous delegate) or when the target type given by context (at compile-time) is MulticastDelegate, Delegate, or Object. Anonymous delegates are derived from MulticastDelegate and are implicitly convertible to all compatible delegate types. A formal definition of delegate compatibility can be found in the language specification. |
||
< |
<syntaxhighlight lang="vbnet">Module Program |
||
' Uses the System generic delegate; see C# entry for details. |
' Uses the System generic delegate; see C# entry for details. |
||
Function [Call](f As Func(Of Integer, Integer, Integer), a As Integer, b As Integer) As Integer |
Function [Call](f As Func(Of Integer, Integer, Integer), a As Integer, b As Integer) As Integer |
||
Line 4,210: | Line 4,210: | ||
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, [Call](anon, a, b)) |
Console.WriteLine("f=Div, f({0}, {1}) = {2}", a, b, [Call](anon, a, b)) |
||
End Sub |
End Sub |
||
End Module</ |
End Module</syntaxhighlight> |
||
=={{header|Visual Prolog}}== |
=={{header|Visual Prolog}}== |
||
<syntaxhighlight lang="prolog"> |
|||
<lang Prolog> |
|||
domains |
domains |
||
intFunction = (integer In) -> integer Out procedure (i). |
intFunction = (integer In) -> integer Out procedure (i). |
||
Line 4,231: | Line 4,231: | ||
write(dotwice(addone,2)), |
write(dotwice(addone,2)), |
||
succeed(). |
succeed(). |
||
</syntaxhighlight> |
|||
</lang> |
|||
=={{header|Wren}}== |
=={{header|Wren}}== |
||
< |
<syntaxhighlight lang="ecmascript">var first = Fn.new { |f| |
||
System.print("first function called") |
System.print("first function called") |
||
f.call() |
f.call() |
||
Line 4,241: | Line 4,241: | ||
var second = Fn.new { System.print("second function called") } |
var second = Fn.new { System.print("second function called") } |
||
first.call(second)</ |
first.call(second)</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
Line 4,257: | Line 4,257: | ||
In fact, it is <b>mandatory</b> to pass the IRQ handler by value on the Game Boy if your game uses hardware sprites, as during direct memory access the CPU loses the ability to access the cartridge, including code execution! Therefore, the code that initiates direct memory access must be copied to RAM from the cartridge ROM and executed from RAM. Since interrupt vectors are in ROM, the vBlank interrupt vector will immediately jump to RAM. Interrupts are disabled immediately after powering on, so we've got all the time we need to copy the interrupt handler to RAM. Once we enable IRQs, the code we copied must remain there or else the game will crash. |
In fact, it is <b>mandatory</b> to pass the IRQ handler by value on the Game Boy if your game uses hardware sprites, as during direct memory access the CPU loses the ability to access the cartridge, including code execution! Therefore, the code that initiates direct memory access must be copied to RAM from the cartridge ROM and executed from RAM. Since interrupt vectors are in ROM, the vBlank interrupt vector will immediately jump to RAM. Interrupts are disabled immediately after powering on, so we've got all the time we need to copy the interrupt handler to RAM. Once we enable IRQs, the code we copied must remain there or else the game will crash. |
||
< |
<syntaxhighlight lang="z80">org &0040 ;Game Boy's vblank IRQ goes here. |
||
;This is not part of the standard Z80 vector table - interrupts work differently on the Game Boy. |
;This is not part of the standard Z80 vector table - interrupts work differently on the Game Boy. |
||
jp &ff80 |
jp &ff80 |
||
Line 4,287: | Line 4,287: | ||
pop af |
pop af |
||
reti |
reti |
||
DMACopyEnd:</ |
DMACopyEnd:</syntaxhighlight> |
||
Line 4,294: | Line 4,294: | ||
=={{header|zkl}}== |
=={{header|zkl}}== |
||
Everything is a first class object so |
Everything is a first class object so |
||
< |
<syntaxhighlight lang="zkl">fcn f(g){ g() } fcn g{ "Hello World!".println() }</syntaxhighlight> |
||
{{out}} |
{{out}} |
||
<pre> |
<pre> |
||
Line 4,301: | Line 4,301: | ||
</pre> |
</pre> |
||
or |
or |
||
< |
<syntaxhighlight lang="zkl">fcn f(g){ g() } |
||
fcn(g){ g() }(fcn{ "Hello World!".println() } )</ |
fcn(g){ g() }(fcn{ "Hello World!".println() } )</syntaxhighlight> |
||
=={{header|ZX Spectrum Basic}}== |
=={{header|ZX Spectrum Basic}}== |
||
{{trans|BBC_BASIC}} |
{{trans|BBC_BASIC}} |
||
Input "FN " token first, then enclose it in double quotation marks. |
Input "FN " token first, then enclose it in double quotation marks. |
||
< |
<syntaxhighlight lang="zxbasic">10 DEF FN f(f$,x,y)=VAL ("FN "+f$+"("+STR$ (x)+","+STR$ (y)+")") |
||
20 DEF FN n(x,y)=(x+y)^2 |
20 DEF FN n(x,y)=(x+y)^2 |
||
30 PRINT FN f("n",10,11)</ |
30 PRINT FN f("n",10,11)</syntaxhighlight> |
||
{{omit from|GUISS}} |
{{omit from|GUISS}} |