Short-circuit evaluation: Difference between revisions
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{{task|Programming language concepts}}
{{Control Structures}}
Assume functions <code>a</code> and <code>b</code> return boolean values, and further, the execution of function <code>b</code> takes considerable resources without side effects, <!--treating the printing as being for illustrative purposes only--> and is to be minimized.
:::: <code>
Then it would be best to not compute the value of <code>b()</code> if the value of <code>a()</code> is computed as <code>false</code>, as the value of <code>x</code> can then only ever be <code> false</code>.
Similarly, if we needed to compute the disjunction (<code>or</code>):
:::: <code> y = a() or b() </code>
Then it would be best to not compute the value of <code>b()</code> if the value of <code>a()</code> is computed as <code>true</code>, as the value of <code>y</code> can then only ever be <code>true</code>.
Some languages will stop further computation of boolean equations as soon as the result is known, so-called [[wp:Short-circuit evaluation|short-circuit evaluation]] of boolean expressions
;Task:
Create two functions named <code>a</code> and <code>b</code>, that take and return the same boolean value.
The functions should also print their name whenever they are called.
Calculate and assign the values of the following equations to a variable in such a way that function <code>b</code> is only called when necessary:
:::: <code> x = a(i) and b(j) </code>
:::: <code> y = a(i) or b(j) </code>
<br>If the language does not have short-circuit evaluation, this might be achieved with nested '''if''' statements.
<br><br>
=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F a(v)
print(‘ ## Called function a(#.)’.format(v))
R v
F b(v)
print(‘ ## Called function b(#.)’.format(v))
R v
L(i) (0B, 1B)
L(j) (0B, 1B)
print("\nCalculating: x = a(i) and b(j)")
V x = a(i) & b(j)
print(‘Calculating: y = a(i) or b(j)’)
V y = a(i) | b(j)</syntaxhighlight>
{{out}}
<pre>
Calculating: x = a(i) and b(j)
# Called function a(0B)
Calculating: y = a(i) or b(j)
# Called function a(0B)
# Called function b(0B)
Calculating: x = a(i) and b(j)
# Called function a(0B)
Calculating: y = a(i) or b(j)
# Called function a(0B)
# Called function b(1B)
Calculating: x = a(i) and b(j)
# Called function a(1B)
# Called function b(0B)
Calculating: y = a(i) or b(j)
# Called function a(1B)
Calculating: x = a(i) and b(j)
# Called function a(1B)
# Called function b(1B)
Calculating: y = a(i) or b(j)
# Called function a(1B)
</pre>
=={{header|6502 Assembly}}==
There are no built-in booleans but the functionality can be easily implemented with 0 = False and 255 = True.
Source Code for the module:
<syntaxhighlight lang="6502asm">;DEFINE 0 AS FALSE, $FF as true.
False equ 0
True equ 255
Func_A:
;input: accumulator = value to check. 0 = false, nonzero = true.
;output: 0 if false, 255 if true. Also prints the truth value to the screen.
;USAGE: LDA val JSR Func_A
BEQ .falsehood
load16 z_HL,BoolText_A_True ;lda #<BoolText_A_True sta z_L lda #>BoolText_A_True sta z_H
jsr PrintString
jsr NewLine
LDA #True
rts
.falsehood:
load16 z_HL,BoolText_A_False
jsr PrintString
jsr NewLine
LDA #False
rts
Func_B:
;input: Y = value to check. 0 = false, nonzero = true.
;output: 0 if false, 255 if true. Also prints the truth value to the screen.
;USAGE: LDY val JSR Func_B
TYA
BEQ .falsehood ;return false
load16 z_HL,BoolText_B_True
jsr PrintString
jsr NewLine
LDA #True
rts
.falsehood:
load16 z_HL,BoolText_B_False
jsr PrintString
jsr NewLine
LDA #False
rts
Func_A_and_B:
;input:
; z_B = input for Func_A
; z_C = input for Func_B
;output:
;0 if false, 255 if true
LDA z_B
jsr Func_A
BEQ .falsehood
LDY z_C
jsr Func_B
BEQ .falsehood
;true
load16 z_HL,BoolText_A_and_B_True
jsr PrintString
jsr NewLine
LDA #True
rts
.falsehood:
load16 z_HL,BoolText_A_and_B_False
jsr PrintString
jsr NewLine
LDA #False
rts
Func_A_or_B:
;input:
; z_B = input for Func_A
; z_C = input for Func_B
;output:
;0 if false, 255 if true
LDA z_B
jsr Func_A
BNE .truth
LDY z_C
jsr Func_B
BNE .truth
;false
load16 z_HL,BoolText_A_or_B_False
jsr PrintString
LDA #False
rts
.truth:
load16 z_HL,BoolText_A_or_B_True
jsr PrintString
LDA #True
rts
BoolText_A_True:
db "A IS TRUE",0
BoolText_A_False:
db "A IS FALSE",0
BoolText_B_True:
db "B IS TRUE",0
BoolText_B_False:
db "B IS FALSE",0
BoolText_A_and_B_True:
db "A AND B IS TRUE",0
BoolText_A_and_B_False:
db "A AND B IS FALSE",0
BoolText_A_or_B_True:
db "A OR B IS TRUE",0
BoolText_A_or_B_False:
db "A OR B IS FALSE",0</syntaxhighlight>
The relevant code for the actual invoking of the functions:
<syntaxhighlight lang="6502asm">lda #True
sta z_B
lda #True
sta z_C
jsr Func_A_and_B
jsr NewLine
jsr Func_A_or_B
jmp *</syntaxhighlight>
And finally the output:
[[https://i.ibb.co/TTJRphL/shortcircuit.png Output image]]
=={{header|Action!}}==
<syntaxhighlight lang="action!">BYTE FUNC a(BYTE x)
PrintF(" a(%B)",x)
RETURN (x)
BYTE FUNC b(BYTE x)
PrintF(" b(%B)",x)
RETURN (x)
PROC Main()
BYTE i,j
FOR i=0 TO 1
DO
FOR j=0 TO 1
DO
PrintF("Calculating %B AND %B: call",i,j)
IF a(i)=1 AND b(j)=1 THEN
FI
PutE()
OD
OD
PutE()
FOR i=0 TO 1
DO
FOR j=0 TO 1
DO
PrintF("Calculating %B OR %B: call",i,j)
IF a(i)=1 OR b(j)=1 THEN
FI
PutE()
OD
OD
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Short-circuit_evaluation.png Screenshot from Atari 8-bit computer]
<pre>
Calculating 0 AND 0: call a(0)
Calculating 0 AND 1: call a(0)
Calculating 1 AND 0: call a(1) b(0)
Calculating 1 AND 1: call a(1) b(1)
Calculating 0 OR 0: call a(0) b(0)
Calculating 0 OR 1: call a(0) b(1)
Calculating 1 OR 0: call a(1)
Calculating 1 OR 1: call a(1)
</pre>
=={{header|Ada}}==
Ada has built-in short-circuit operations '''and then''' and '''or else''':
<syntaxhighlight lang="ada">with Ada.Text_IO; use Ada.Text_IO;
procedure Test_Short_Circuit is
Line 47 ⟶ 281:
end loop;
end loop;
end Test_Short_Circuit;</syntaxhighlight>
{{out|Sample output}}
<pre>
A=FALSE (A and then B)=FALSE
Line 64 ⟶ 297:
===With Standard===
{{works with|ALGOL 68|Revision 1 - no extensions to language used}}
{{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|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]}}
Note: The "brief" ''conditional clause'' ( ~ | ~ | ~ ) is a the standard's ''shorthand'' for enforcing ''short-circuit evaluation''. Moreover, the coder is able to define their own '''proc'''[edures] and '''op'''[erators] that implement ''short-circuit evaluation'' by using Algol68's ''proceduring''.
<
OP ORELSE = (BOOL a, PROC BOOL b)BOOL: ( a | a | b ),
ANDTHEN = (BOOL a, PROC BOOL b)BOOL: ( a | b | a );
Line 107 ⟶ 337:
print(("T ANDTHEN T = ", a(TRUE) ANDTHEN (BOOL:b(TRUE)), new line))
)</
{{out}}
<pre>
a=T, T ORELSE F = T
Line 122 ⟶ 352:
===With Extensions===
{{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|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]}}
<
PROC a = (BOOL a)BOOL: ( print(("a=",a,", ")); a),
Line 148 ⟶ 377:
END CO
)</
{{out}}
<pre>
a=T, T OREL F = T
Line 160 ⟶ 389:
a=T, b=T, T ANDTH T = T
</pre>
=={{header|ALGOL W}}==
In Algol W the boolean "and" and "or" operators are short circuit operators.
<syntaxhighlight lang="algolw">begin
logical procedure a( logical value v ) ; begin write( "a: ", v ); v end ;
logical procedure b( logical value v ) ; begin write( "b: ", v ); v end ;
write( "and: ", a( true ) and b( true ) );
write( "---" );
write( "or: ", a( true ) or b( true ) );
write( "---" );
write( "and: ", a( false ) and b( true ) );
write( "---" );
write( "or: ", a( false ) or b( true ) );
write( "---" );
end.</syntaxhighlight>
{{out}}
<pre>
and:
a: true
b: true true
---
or:
a: true true
---
and:
a: false false
---
or:
a: false
b: true true
---
</pre>
=={{header|AppleScript}}==
AppleScript's boolean operators are short-circuiting (as can be seen from the log below).
What AppleScript lacks, however, is a short-circuiting ternary operator like the '''e ? e2 : e3''' of C, or a short-circuiting three-argument function like '''cond''' in Lisp. To get a similar effect in AppleScript, we have to delay evaluation on both sides, using a '''cond''' which returns a reference to one of two unapplied handlers, and composing the result with a separate '''apply''' function, to apply the selected handler function to its argument.
(As a statement, rather than an expression, the ''if ... then ... else'' structure does not compose – unlike ''cond'' or ''? :'', it can not be nested inside expressions)
<syntaxhighlight lang="applescript">on run
map(test, {|and|, |or|})
end run
-- test :: ((Bool, Bool) -> Bool) -> (Bool, Bool, Bool, Bool)
on test(f)
map(f, {{true, true}, {true, false}, {false, true}, {false, false}})
end test
-- |and| :: (Bool, Bool) -> Bool
on |and|(tuple)
set {x, y} to tuple
a(x) and b(y)
end |and|
-- |or| :: (Bool, Bool) -> Bool
on |or|(tuple)
set {x, y} to tuple
a(x) or b(y)
end |or|
-- a :: Bool -> Bool
on a(bool)
log "a"
return bool
end a
-- b :: Bool -> Bool
on b(bool)
log "b"
return bool
end b
-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
script mf
property lambda : f
end script
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to mf's lambda(item i of xs, i, xs)
end repeat
return lst
end map
</syntaxhighlight>
{{Out}}
<pre>Messages:
(*a*)
(*b*)
(*a*)
(*b*)
(*a*)
(*a*)
(*a*)
(*a*)
(*a*)
(*b*)
(*a*)
(*b*)
Result:
{{true, false, false, false}, {true, true, true, false}}
</pre>
=={{header|Arturo}}==
<syntaxhighlight lang="arturo">a: function [v][
print ["called function A with:" v]
v
]
b: function [v][
print ["called function B with:" v]
v
]
loop @[true false] 'i ->
loop @[true false] 'j ->
print ["\tThe result of A(i) AND B(j) is:" and? -> a i -> b j]
print ""
loop @[true false] 'i ->
loop @[true false] 'j ->
print ["\tThe result of A(i) OR B(j) is:" or? -> a i -> b j]</syntaxhighlight>
{{out}}
<pre>called function A with: true
called function B with: true
The result of A(i) AND B(j) is: true
called function A with: true
called function B with: false
The result of A(i) AND B(j) is: false
called function A with: false
The result of A(i) AND B(j) is: false
called function A with: false
The result of A(i) AND B(j) is: false
called function A with: true
The result of A(i) OR B(j) is: true
called function A with: true
The result of A(i) OR B(j) is: true
called function A with: false
called function B with: true
The result of A(i) OR B(j) is: true
called function A with: false
called function B with: false
The result of A(i) OR B(j) is: false</pre>
=={{header|AutoHotkey}}==
In AutoHotkey, the boolean operators, '''and''', '''or''', and ternaries, short-circuit:
<syntaxhighlight lang="autohotkey">i = 1
j = 1
x := a(i) and b(j)
y := a(i) or b(j)
a(p)
{
MsgBox, a() was called with the parameter "%p%".
Return, p
}
b(p)
{
MsgBox, b() was called with the parameter "%p%".
Return, p
}</syntaxhighlight>
=={{header|AWK}}==
Short-circuit evalation is done in logical AND (&&) and logical OR (||) operators:
<syntaxhighlight lang="awk">#!/usr/bin/awk -f
BEGIN {
print (a(1) && b(1))
print (a(1) || b(1))
print (a(0) && b(1))
print (a(0) || b(1))
}
function a(x) {
print " x:"x
return x
}
function b(y) {
print " y:"y
return y
}</syntaxhighlight>
{{out}}
<pre>
x:1
y:1
1
x:1
1
x:0
0
x:0
y:1
1
</pre>
=={{header|Axe}}==
<syntaxhighlight lang="axe">TEST(0,0)
TEST(0,1)
TEST(1,0)
TEST(1,1)
Return
Lbl TEST
r₁→X
r₂→Y
Disp X▶Hex+3," and ",Y▶Hex+3," = ",(A(X)?B(Y))▶Hex+3,i
Disp X▶Hex+3," or ",Y▶Hex+3," = ",(A(X)??B(Y))▶Hex+3,i
.Wait for keypress
getKeyʳ
Return
Lbl A
r₁
Return
Lbl B
r₁
Return</syntaxhighlight>
=={{header|BASIC}}==
==={{header|BaCon}}===
BaCon supports short-circuit evaluation.
<syntaxhighlight lang="freebasic">' Short-circuit evaluation
FUNCTION a(f)
PRINT "FUNCTION a"
RETURN f
END FUNCTION
FUNCTION b(f)
PRINT "FUNCTION b"
RETURN f
END FUNCTION
PRINT "FALSE and TRUE"
x = a(FALSE) AND b(TRUE)
PRINT x
PRINT "TRUE and TRUE"
x = a(TRUE) AND b(TRUE)
PRINT x
PRINT "FALSE or FALSE"
y = a(FALSE) OR b(FALSE)
PRINT y
PRINT "TRUE or FALSE"
y = a(TRUE) OR b(FALSE)
PRINT y</syntaxhighlight>
{{out}}
<pre>prompt$ ./short-circuit
FALSE and TRUE
FUNCTION a
0
TRUE and TRUE
FUNCTION a
FUNCTION b
1
FALSE or FALSE
FUNCTION a
FUNCTION b
0
TRUE or FALSE
FUNCTION a
1</pre>
=={{header|Batch File}}==
{{trans|Liberty BASIC}}
<syntaxhighlight lang="dos">%=== Batch Files have no booleans on if command, let alone short-circuit evaluation ===%
%=== I will instead use 1 as true and 0 as false. ===%
@echo off
setlocal enabledelayedexpansion
echo AND
for /l %%i in (0,1,1) do (
for /l %%j in (0,1,1) do (
echo.a^(%%i^) AND b^(%%j^)
call :a %%i
set res=!bool_a!
if not !res!==0 (
call :b %%j
set res=!bool_b!
)
echo.=^> !res!
)
)
echo ---------------------------------
echo OR
for /l %%i in (0,1,1) do (
for /l %%j in (0,1,1) do (
echo a^(%%i^) OR b^(%%j^)
call :a %%i
set res=!bool_a!
if !res!==0 (
call :b %%j
set res=!bool_b!
)
echo.=^> !res!
)
)
pause>nul
exit /b 0
::----------------------------------------
:a
echo. calls func a
set bool_a=%1
goto :EOF
:b
echo. calls func b
set bool_b=%1
goto :EOF</syntaxhighlight>
{{Out}}
<pre>AND
a(0) AND b(0)
calls func a
=> 0
a(0) AND b(1)
calls func a
=> 0
a(1) AND b(0)
calls func a
calls func b
=> 0
a(1) AND b(1)
calls func a
calls func b
=> 1
---------------------------------
OR
a(0) OR b(0)
calls func a
calls func b
=> 0
a(0) OR b(1)
calls func a
calls func b
=> 1
a(1) OR b(0)
calls func a
=> 1
a(1) OR b(1)
calls func a
=> 1
</pre>
=={{header|BBC BASIC}}==
Short-circuit operators aren't implemented directly, but short-circuit AND can be simulated using cascaded IFs. Short-circuit OR can be converted into a short-circuit AND using De Morgan's laws.
<syntaxhighlight lang="bbcbasic"> REM TRUE is represented as -1, FALSE as 0
FOR i% = TRUE TO FALSE
FOR j% = TRUE TO FALSE
PRINT "For x=a(";FNboolstring(i%);") AND b(";FNboolstring(j%);")"
x% = FALSE
REM Short-circuit AND can be simulated by cascaded IFs:
IF FNa(i%) IF FNb(j%) THEN x%=TRUE
PRINT "x is ";FNboolstring(x%)
PRINT
PRINT "For y=a(";FNboolstring(i%);") OR b(";FNboolstring(j%);")"
y% = FALSE
REM Short-circuit OR can be simulated by De Morgan's laws:
IF NOTFNa(i%) IF NOTFNb(j%) ELSE y%=TRUE : REM Note ELSE without THEN
PRINT "y is ";FNboolstring(y%)
PRINT
NEXT:NEXT
END
DEFFNa(bool%)
PRINT "Function A used; ";
=bool%
DEFFNb(bool%)
PRINT "Function B used; ";
=bool%
DEFFNboolstring(bool%)
IF bool%=0 THEN ="FALSE" ELSE="TRUE"</syntaxhighlight>
This gives the results shown below:
<pre>For x=a(TRUE) AND b(TRUE)
Function A used; Function B used; x is TRUE
For y=a(TRUE) OR b(TRUE)
Function A used; y is TRUE
For x=a(TRUE) AND b(FALSE)
Function A used; Function B used; x is FALSE
For y=a(TRUE) OR b(FALSE)
Function A used; y is TRUE
For x=a(FALSE) AND b(TRUE)
Function A used; x is FALSE
For y=a(FALSE) OR b(TRUE)
Function A used; Function B used; y is TRUE
For x=a(FALSE) AND b(FALSE)
Function A used; x is FALSE
For y=a(FALSE) OR b(FALSE)
Function A used; Function B used; y is FALSE
</pre>
=={{header|Bracmat}}==
Bracmat has no booleans. The closest thing is the success or failure of an expression. A function is not called if the argument fails, so we have to use a trick to pass 'failure' to a function. Here it is accomplished by an extra level of indirection: two == in the definition of 'false' (and 'true', for symmetry) and two !! when evaluating the argument in the functions a and b. The backtick is another hack. This prefix tells Bracmat to look the other way if the backticked expression fails and to continue as if the expression succeeded. A neater way is to introduce an extra OR operator. That solution would have obscured the core of the current task.
Short-circuit evaluation is heavily used in Bracmat code. Although not required, it is a good habit to exclusively use AND (&) and OR (|) operators to separate expressions, as the code below exemplifies.
<syntaxhighlight lang="bracmat">( (a=.out$"I'm a"&!!arg)
& (b=.out$"I'm b"&!!arg)
& (false==~)
& (true==)
& !false !true:?outer
& whl
' ( !outer:%?x ?outer
& !false !true:?inner
& whl
' ( !inner:%?y ?inner
& out
$ ( Testing
(!!x&true|false)
AND
(!!y&true|false)
)
& `(a$!x&b$!y)
& out
$ ( Testing
(!!x&true|false)
OR
(!!y&true|false)
)
& `(a$!x|b$!y)
)
)
& done
);
</syntaxhighlight>
Output:
<pre>Testing false AND false
I'm a
Testing false OR false
I'm a
I'm b
Testing false AND true
I'm a
Testing false OR true
I'm a
I'm b
Testing true AND false
I'm a
I'm b
Testing true OR false
I'm a
Testing true AND true
I'm a
I'm b
Testing true OR true
I'm a</pre>
=={{header|C}}==
Boolean operators <nowiki>&&</nowiki> and || are shortcircuit operators.
<syntaxhighlight lang="c">#include <stdio.h>
#include <stdbool.h>
bool a(bool in)
{
printf("I am a\n");
return in;
}
bool b(bool in)
{
printf("I am b\n");
return in;
}
#define TEST(X,Y,O) \
do { \
x = a(X) O b(Y); \
printf(#X " " #O " " #Y " = %s\n\n", x ? "true" : "false"); \
} while(false);
int main()
{
bool x;
TEST(false, true, &&); // b is not evaluated
TEST(true, false, ||); // b is not evaluated
TEST(true, false, &&); // b is evaluated
TEST(false, false, ||); // b is evaluated
return 0;
}</syntaxhighlight>
=={{header|C sharp|C#}}==
<syntaxhighlight lang="csharp">using System;
class Program
{
static bool a(bool value)
{
Console.WriteLine("a");
return value;
}
static bool b(bool value)
{
Console.WriteLine("b");
return value;
}
static void Main()
{
foreach (var i in new[] { false, true })
{
foreach (var j in new[] { false, true })
{
Console.WriteLine("{0} and {1} = {2}", i, j, a(i) && b(j));
Console.WriteLine();
Console.WriteLine("{0} or {1} = {2}", i, j, a(i) || b(j));
Console.WriteLine();
}
}
}
}</syntaxhighlight>
{{out}}
<syntaxhighlight lang="text">a
False and False = False
a
b
False or False = False
a
False and True = False
a
b
False or True = True
a
b
True and False = False
a
True or False = True
a
b
True and True = True
a
True or True = True</syntaxhighlight>
=={{header|C++}}==
Just like C, boolean operators <nowiki>&&</nowiki> and || are shortcircuit operators.
<syntaxhighlight lang="cpp">#include <iostream>
bool a(bool in)
{
std::cout << "a" << std::endl;
return in;
}
bool b(bool in)
{
std::cout << "b" << std::endl;
return in;
}
void test(bool i, bool j) {
std::cout << std::boolalpha << i << " and " << j << " = " << (a(i) && b(j)) << std::endl;
std::cout << std::boolalpha << i << " or " << j << " = " << (a(i) || b(j)) << std::endl;
}
int main()
{
test(false, false);
test(false, true);
test(true, false);
test(true, true);
return 0;
}</syntaxhighlight>
{{out}}
<pre>a
false and false = false
a
b
false or false = false
a
false and true = false
a
b
false or true = true
a
b
true and false = false
a
true or false = true
a
b
true and true = true
a
true or true = true</pre>
=={{header|Clojure}}==
The print/println stuff in the doseq is kinda gross, but if you include them all in a single print, then the function traces are printed before the rest (since it has to evaluate them before calling print).
<
(b [bool] (print "(b)") bool)]
(doseq [i [true false] j [true false]]
Line 169 ⟶ 1,024:
(println (or (a i) (b j)))
(print i "AND" j " = ")
(println (and (a i) (b j)))))</
{{out}}
<pre>true OR true = (a)true
true AND true = (a)(b)true
Line 179 ⟶ 1,034:
false OR false = (a)(b)false
false AND false = (a)false</pre>
=={{header|Common Lisp}}==
<syntaxhighlight lang="lisp">(defun a (F)
(print 'a)
F )
(defun b (F)
(print 'b)
F )
(dolist (x '((nil nil) (nil T) (T T) (T nil)))
(format t "~%(and ~S)" x)
(and (a (car x)) (b (car(cdr x))))
(format t "~%(or ~S)" x)
(or (a (car x)) (b (car(cdr x)))))</syntaxhighlight>
{{out}}
(and (NIL NIL))
A
(or (NIL NIL))
A
B
(and (NIL T))
A
(or (NIL T))
A
B
(and (T T))
A
B
(or (T T))
A
(and (T NIL))
A
B
(or (T NIL))
A
=={{header|D}}==
{{trans|Python}}
<
T a(T)(T answer) {
Line 195 ⟶ 1,086:
void main() {
foreach (
immutable
immutable
}</
{{out}}
<pre>
Calculating:
# Called function a(false) -> false
Calculating:
# Called function a(false) -> false
# Called function b(false) -> false
Calculating:
# Called function a(true) -> true
# Called function b(false) -> false
Calculating:
# Called function a(true) -> true
Calculating:
# Called function a(false) -> false
Calculating: r2 = a(x) || b(y)
# Called function a(false) -> false
# Called function b(true) -> true
Calculating: r1 = a(x) && b(y)
# Called function a(true) -> true
# Called function b(true) -> true
Calculating:
# Called function a(true) -> true</pre>
=={{header|
Delphi supports short circuit evaluation by default. It can be turned off using the {$BOOLEVAL OFF} compiler directive.
<syntaxhighlight lang="delphi">program ShortCircuitEvaluation;
{$APPTYPE CONSOLE}
uses SysUtils;
function A(aValue: Boolean): Boolean;
begin
Writeln('a');
Result := aValue;
end;
function B(aValue: Boolean): Boolean;
begin
Writeln('b');
Result := aValue;
end;
var
i, j: Boolean;
begin
for i in [False, True] do
begin
for j in [False, True] do
begin
Writeln(Format('%s and %s = %s', [BoolToStr(i, True), BoolToStr(j, True), BoolToStr(A(i) and B(j), True)]));
Writeln;
Writeln(Format('%s or %s = %s', [BoolToStr(i, True), BoolToStr(j, True), BoolToStr(A(i) or B(j), True)]));
Writeln;
end;
end;
end.</syntaxhighlight>
=={{header|Dyalect}}==
{{trans|Swift}}
<syntaxhighlight lang="dyalect">func a(v) {
print(nameof(a), terminator: "")
return v
}
func b(v) {
print(nameof(b), terminator: "")
return v
}
func testMe(i, j) {
print("Testing a(\(i)) && b(\(j))")
print("Trace: ", terminator: "")
print("\nResult: \(a(i) && b(j))")
print("Testing a(\(i)) || b(\(j))")
print("Trace: ", terminator: "")
print("\nResult: \(a(i) || b(j))")
print()
}
testMe(false, false)
testMe(false, true)
testMe(true, false)
testMe(true, true)</syntaxhighlight>
{{out}}
<pre>Testing a(false) && b(false)
Trace: a
Result: false
Testing a(false) || b(false)
Trace: ab
Result: false
Testing a(false) && b(true)
Trace: a
Result: false
Testing a(false) || b(true)
Trace: ab
Result: true
Testing a(true) && b(false)
Trace: ab
Result: false
Testing a(true) || b(false)
Trace: a
Result: true
Testing a(true) && b(true)
Trace: ab
Result: true
Testing a(true) || b(true)
Trace: a
Result: true</pre>
=={{header|E}}==
E defines <code>&&</code> and <code>||</code> in the usual short-circuiting fashion.
<syntaxhighlight lang="e">def a(v) { println("a"); return v }
def b(v) { println("b"); return v }
def x := a(i) && b(j)
def y := b(i) || b(j)</
Unusually, E is an expression-oriented language, and variable bindings (which are expressions) are in scope until the end of the nearest enclosing <code>{ ... }</code> block. The combination of these features means that some semantics must be given to a binding occurring inside of a short-circuited alternative.
<syntaxhighlight lang="e">def x := a(i) && (def funky := b(j))</syntaxhighlight>
The choice we make is that <code>funky</code> is ordinary if the right-side expression was evaluated, and otherwise is <em>ruined</em>; attempts to access the variable give an error.
=={{header|EasyLang}}==
<syntaxhighlight lang=easylang>
func a x .
print "->a: " & x
return x
.
func b x .
print "->b: " & x
return x
.
print "1 and 1"
if a 1 = 1 and b 1 = 1
print "-> true"
.
print ""
print "1 or 1"
if a 1 = 1 or b 1 = 1
print "-> true"
.
print ""
print "0 and 1"
if a 0 = 1 and b 1 = 1
print "-> true"
.
print ""
print "0 or 1"
if a 0 = 1 or b 1 = 1
print "-> true"
.
</syntaxhighlight>
=={{header|Ecstasy}}==
Similar to Java, Ecstasy uses the <span style="background-color: #e5e4e2"> && </tt></span> and <span style="background-color: #e5e4e2"><tt> || </tt></span> operators for short-circuiting logic, and <span style="background-color: #e5e4e2"><tt> & </tt></span> and <span style="background-color: #e5e4e2"><tt> | </tt></span> are the normal (non-short-circuiting) forms.
<syntaxhighlight lang="java">
module test {
@Inject Console console;
static Boolean show(String name, Boolean value) {
console.print($"{name}()={value}");
}
void run() {
val a = show("a", _);
val b = show("b", _);
for (Boolean v1 : False..True) {
for (Boolean v2 : False..True) {
console.print($"a({v1}) && b({v2}) == {a(v1) && b(v2)}");
console.print();
console.print($"a({v1}) || b({v2}) == {a(v1) || b(v2)}");
console.print();
}
}
}
}
</syntaxhighlight>
{{out}}
<pre>
a()=False
a(False) && b(False) == False
a()=False
b()=False
a(False) || b(False) == False
a()=False
a(False) && b(True) == False
a()=False
b()=True
a(False) || b(True) == True
a()=True
b()=False
a(True) && b(False) == False
a()=True
a(True) || b(False) == True
a()=True
b()=True
a(True) && b(True) == True
a()=True
a(True) || b(True) == True
</pre>
=={{header|Elena}}==
ELENA 6.x :
<syntaxhighlight lang="elena">import system'routines;
import extensions;
Func<bool, bool> a = (bool x){ console.writeLine("a"); ^ x };
Func<bool, bool> b = (bool x){ console.writeLine("b"); ^ x };
const bool[] boolValues = new bool[]{ false, true };
public program()
{
boolValues.forEach::(bool i)
{
boolValues.forEach::(bool j)
{
console.printLine(i," and ",j," = ",a(i) && b(j));
console.writeLine();
console.printLine(i," or ",j," = ",a(i) || b(j));
console.writeLine()
}
}
}</syntaxhighlight>
{{out}}
<pre>
a
false and false = false
a
b
false or false = false
a
false and true = false
a
b
false or true = true
a
b
true and false = false
a
true or false = true
a
b
true and true = true
a
true or true = true
</pre>
=={{header|Elixir}}==
<syntaxhighlight lang="elixir">defmodule Short_circuit do
defp a(bool) do
IO.puts "a( #{bool} ) called"
bool
end
defp b(bool) do
IO.puts "b( #{bool} ) called"
bool
end
def task do
Enum.each([true, false], fn i ->
Enum.each([true, false], fn j ->
IO.puts "a( #{i} ) and b( #{j} ) is #{a(i) and b(j)}.\n"
IO.puts "a( #{i} ) or b( #{j} ) is #{a(i) or b(j)}.\n"
end)
end)
end
end
Short_circuit.task</syntaxhighlight>
{{out}}
<pre>
a( true ) called
b( true ) called
a( true ) and b( true ) is true.
a( true ) called
a( true ) or b( true ) is true.
a( true ) called
b( false ) called
a( true ) and b( false ) is false.
a( true ) called
a( true ) or b( false ) is true.
a( false ) called
a( false ) and b( true ) is false.
a( false ) called
b( true ) called
a( false ) or b( true ) is true.
a( false ) called
a( false ) and b( false ) is false.
a( false ) called
b( false ) called
a( false ) or b( false ) is false.
</pre>
=={{header|Erlang}}==
<syntaxhighlight lang="erlang">
-module( short_circuit_evaluation ).
-export( [task/0] ).
task() ->
[task_helper(X, Y) || X <- [true, false], Y <- [true, false]].
a( Boolean ) ->
io:fwrite( " a ~p~n", [Boolean] ),
Boolean.
b( Boolean ) ->
io:fwrite( " b ~p~n", [Boolean] ),
Boolean.
task_helper( Boolean1, Boolean2 ) ->
io:fwrite( "~p andalso ~p~n", [Boolean1, Boolean2] ),
io:fwrite( "=> ~p~n", [a(Boolean1) andalso b(Boolean2)] ),
io:fwrite( "~p orelse ~p~n", [Boolean1, Boolean2] ),
io:fwrite( "=> ~p~n", [a(Boolean1) orelse b(Boolean2)] ).
</syntaxhighlight>
{{out}}
<pre>
15> short_circuit_evaluation:task().
true andalso true
a true
b true
=> true
true orelse true
a true
=> true
true andalso false
a true
b false
=> false
true orelse false
a true
=> true
false andalso true
a false
=> false
false orelse true
a false
b true
=> true
false andalso false
a false
=> false
false orelse false
a false
b false
=> false
</pre>
=={{header|F_Sharp|F#}}==
<syntaxhighlight lang="fsharp">let a (x : bool) = printf "(a)"; x
let b (x : bool) = printf "(b)"; x
[for x in [true; false] do for y in [true; false] do yield (x, y)]
|> List.iter (fun (x, y) ->
printfn "%b AND %b = %b" x y ((a x) && (b y))
printfn "%b OR %b = %b" x y ((a x) || (b y)))</syntaxhighlight>
Output
<pre>(a)(b)true AND true = true
(a)true OR true = true
(a)(b)true AND false = false
(a)true OR false = true
(a)false AND true = false
(a)(b)false OR true = true
(a)false AND false = false
(a)(b)false OR false = false</pre>
=={{header|Factor}}==
<code>&&</code> and <code>||</code> perform short-circuit evaluation, while <code>and</code> and <code>or</code> do not. <code>&&</code> and <code>||</code> both expect a sequence of quotations to evaluate in a short-circuit manner. They are smart combinators; that is, they infer the number of arguments taken by the quotations. If you opt not to use the smart combinators, you can also use words like <code>0&&</code> and <code>2||</code> where the arity of the quotations is dictated.
<syntaxhighlight lang="factor">USING: combinators.short-circuit.smart io prettyprint ;
IN: rosetta-code.short-circuit
: a ( ? -- ? ) "(a)" write ;
: b ( ? -- ? ) "(b)" write ;
"f && f = " write { [ f a ] [ f b ] } && .
"f || f = " write { [ f a ] [ f b ] } || .
"f && t = " write { [ f a ] [ t b ] } && .
"f || t = " write { [ f a ] [ t b ] } || .
"t && f = " write { [ t a ] [ f b ] } && .
"t || f = " write { [ t a ] [ f b ] } || .
"t && t = " write { [ t a ] [ t b ] } && .
"t || t = " write { [ t a ] [ t b ] } || .</syntaxhighlight>
{{out}}
<pre>
f && f = (a)f
f || f = (a)(b)f
f && t = (a)f
f || t = (a)(b)t
t && f = (a)(b)f
t || f = (a)t
t && t = (a)(b)t
t || t = (a)t
</pre>
=={{header|Fantom}}==
<syntaxhighlight lang="fantom">class Main
{
static Bool a (Bool value)
{
echo ("in a")
return value
}
static Bool b (Bool value)
{
echo ("in b")
return value
}
public static Void main ()
{
[false,true].each |i|
{
[false,true].each |j|
{
Bool result := a(i) && b(j)
echo ("a($i) && b($j): " + result)
result = a(i) || b(j)
echo ("a($i) || b($j): " + result)
}
}
}
}</syntaxhighlight>
{{out}}
<pre>
in a
a(false) && b(false): false
in a
in b
a(false) || b(false): false
in a
a(false) && b(true): false
in a
in b
a(false) || b(true): true
in a
in b
a(true) && b(false): false
in a
a(true) || b(false): true
in a
in b
a(true) && b(true): true
in a
a(true) || b(true): true
</pre>
=={{header|Forth}}==
<syntaxhighlight lang="forth">\ Short-circuit evaluation definitions from Wil Baden, with minor name changes
: ENDIF postpone THEN ; immediate
: COND 0 ; immediate
: ENDIFS BEGIN DUP WHILE postpone ENDIF REPEAT DROP ; immediate
: ORELSE s" ?DUP 0= IF" evaluate ; immediate
: ANDIF s" DUP IF DROP" evaluate ; immediate
: .bool IF ." true " ELSE ." false " THEN ;
: A ." A=" DUP .bool ;
: B ." B=" DUP .bool ;
: test
CR
1 -1 DO 1 -1 DO
LOOP LOOP ;
\ An alternative based on explicitly short-circuiting conditionals, Dave Keenan
: END-PRIOR-IF 1 CS-ROLL postpone ENDIF ; immediate
: test
CR
1 -1 DO 1 -1 DO
I A IF J B IF 1 ELSE END-PRIOR-IF 0 ENDIF ." ANDIF=" .bool CR
I A 0= IF J B IF END-PRIOR-IF 1 ELSE 0 ENDIF ." ORELSE=" .bool CR
LOOP LOOP ;</syntaxhighlight>
{{out}}
<pre>A=true B=true ANDIF=true
A=true ORELSE=true
A=false ANDIF=false
A=false B=true ORELSE=true
A=true B=false ANDIF=false
A=true ORELSE=true
A=false ANDIF=false
A=false B=false ORELSE=false</pre>
=={{header|Fortran}}==
{{works with|Fortran|90 and later}}
Using an <code>IF .. THEN .. ELSE</code> construct
<syntaxhighlight lang="fortran">program Short_Circuit_Eval
implicit none
Line 321 ⟶ 1,677:
write(*, "(a,l1,a)") "Called function b(", value, ")"
end function
end program</
{{out}}
<pre>Calculating x = a(F) and b(F)
Called function a(F)
Line 359 ⟶ 1,715:
y = T</pre>
=={{header|FreeBASIC}}==
<syntaxhighlight lang="freebasic">' FB 1.05.0 Win64
Function a(p As Boolean) As Boolean
Print "a() called"
Return p
End Function
Function b(p As Boolean) As Boolean
Print "b() called"
Return p
End Function
Dim As Boolean i, j, x, y
i = False
j = True
Print "Without short-circuit evaluation :"
Print
x = a(i) And b(j)
y = a(i) Or b(j)
Print "x = "; x; " y = "; y
Print
Print "With short-circuit evaluation :"
Print
x = a(i) AndAlso b(j) '' b(j) not called as a(i) = false and so x must be false
y = a(i) OrElse b(j) '' b(j) still called as can't determine y unless it is
Print "x = "; x; " y = "; y
Print
Print "Press any key to quit"
Sleep</syntaxhighlight>
{{out}}
<pre>
Without short-circuit evaluation :
a() called
b() called
a() called
b() called
x = false y = true
With short-circuit evaluation :
a() called
a() called
b() called
x = false y = true
</pre>
=={{header|Fōrmulæ}}==
{{FormulaeEntry|page=https://formulae.org/?script=examples/Short-circuit_evaluation}}
'''Solution'''
[[File:Fōrmulæ - Short-circuit evaluation 01.png]]
[[File:Fōrmulæ - Short-circuit evaluation 02.png]]
=={{header|Go}}==
Short circuit operators are <nowiki>&&</nowiki> and ||.
<syntaxhighlight lang="go">package main
import "fmt"
func a(v bool) bool {
fmt.Print("a")
return v
}
func b(v bool) bool {
fmt.Print("b")
return v
}
func test(i, j bool) {
fmt.Printf("Testing a(%t) && b(%t)\n", i, j)
fmt.Print("Trace: ")
fmt.Println("\nResult:", a(i) && b(j))
fmt.Printf("Testing a(%t) || b(%t)\n", i, j)
fmt.Print("Trace: ")
fmt.Println("\nResult:", a(i) || b(j))
fmt.Println("")
}
func main() {
test(false, false)
test(false, true)
test(true, false)
test(true, true)
}</syntaxhighlight>
{{out}}
<pre>Testing a(false) && b(false)
Trace: a
Result: false
Testing a(false) || b(false)
Trace: ab
Result: false
Testing a(false) && b(true)
Trace: a
Result: false
Testing a(false) || b(true)
Trace: ab
Result: true
Testing a(true) && b(false)
Trace: ab
Result: false
Testing a(true) || b(false)
Trace: a
Result: true
Testing a(true) && b(true)
Trace: ab
Result: true
Testing a(true) || b(true)
Trace: a
Result: true</pre>
=={{header|Groovy}}==
Like all C-based languages (of which I am aware), Groovy short-circuits the logical and (<nowiki>&&</nowiki>) and logical or (||) operations, but not the bitwise and (<nowiki>&</nowiki>) and bitwise or (|) operations.
<syntaxhighlight lang="groovy">def f = { println ' AHA!'; it instanceof String }
def g = { printf ('%5d ', it); it > 50 }
println 'bitwise'
assert g(100) & f('sss')
assert g(2) | f('sss')
assert ! (g(1) & f('sss'))
assert g(200) | f('sss')
println '''
logical'''
assert g(100) && f('sss')
assert g(2) || f('sss')
assert ! (g(1) && f('sss'))
assert g(200) || f('sss')</syntaxhighlight>
{{out}}
<pre>bitwise
100 AHA!
2 AHA!
1 AHA!
200 AHA!
logical
100 AHA!
2 AHA!
1 200</pre>
=={{header|Haskell}}==
[[Lazy evaluation]] makes it possible for user-defined functions to be short-circuited. An expression will not be evaluated as long as it is not [[pattern matching|pattern matched]]:
<syntaxhighlight lang="haskell">module ShortCircuit where
import Prelude hiding ((&&), (||))
import Debug.Trace
False && _ = False
True && False = False
_ && _ = True
True || _ = True
False || True = True
_ || _ = False
a p = trace ("<a " ++ show p ++ ">") p
b p = trace ("<b " ++ show p ++ ">") p
main = mapM_ print ( [ a p || b q | p <- [False, True], q <- [False, True] ]
++ [ a p && b q | p <- [False, True], q <- [False, True] ])</syntaxhighlight>
{{out}}
<pre>
<a False>
<b False>
False
<a False>
<b True>
True
<a True>
True
<a True>
True
<a False>
False
<a False>
False
<a True>
<b False>
False
<a True>
<b True>
True
</pre>
One can force the right-hand arguemnt to be evaluated first be using the alternate definitions:
<syntaxhighlight lang="haskell">_ && False = False
False && True = False
_ && _ = True
_ || True = True
True || False = True
_ || _ = False</syntaxhighlight>
{{out}}
<pre>
<b False>
<a False>
False
<b True>
True
<b False>
<a True>
True
<b True>
True
<b False>
False
<b True>
<a False>
False
<b False>
False
<b True>
<a True>
True
</pre>
The order of evaluation (in this case the original order again) can be seen in a more explicit form by [[syntactic sugar|desugaring]] the pattern matching:
<syntaxhighlight lang="haskell">p && q = case p of
False -> False
_ -> case q of
False -> False
_ -> True
p || q = case p of
True -> True
_ -> case q of
True -> True
_ -> False</syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
The entire concept of using 'boolean' values for logic control runs counter to the philosophy of Icon. Instead Icon has success (something that returns a result) and failure which is really a signal. The concept is similar to that used in [[:Category:SNOBOL4|SNOBOL4]] and [[:Category:Lisp|Lisp]] and far more potent than passing around and testing booleans. There is no way to pass around a 'false' value in that sense. Icon does have facilities for dealing with bits inside integers but these would not normally be used for control purposes. Because failure is a signal control is always evaluated in a short-circuit manner. One consequence of this is that an expression "i < j" doesn't return a boolean value, instead it returns the value of j. While this may seem odd at first it allows for elegant expressions like "i < j < k". Another benefit is that there is no need for programmers to devote effort to staying inside the bounds of any data type. For instance, if you loop and iterate beyond bounds the expression simply fails and the loop ends.
Line 369 ⟶ 1,962:
* Rather than have the tasks print their own name, we will just utilize built-in tracing which will be more informative.
This use of procedures as values is somewhat contrived but serves us well for demonstration purposes. In practice this approach would be strained since failure results aren't re-captured as values (and can't easily be).
<syntaxhighlight lang="icon">procedure main()
&trace := -1 # ensures functions print their names
Line 388 ⟶ 1,980:
procedure false() #: fails always
fail # for clarity but not needed as running into end has the same effect
end</syntaxhighlight>
Sample output for a single case:<pre>i,j := procedure true, procedure false
i & j:
Line 401 ⟶ 1,992:
i,j := procedure true, procedure true</pre>
{{trans|Clojure}}
<syntaxhighlight lang="insitux">
(let a (fn (print-str "a ") %)
b (fn (print-str "b ") %)
f (pad-right " " 6))
(for i [true false] j [true false]
(print-str (f i) "OR " (f j) " = ")
(print (or (a i) (b j)))
(print-str (f i) "AND " (f j) " = ")
(print (and (a i) (b j))))
</syntaxhighlight>
{{out}}
<pre>
true OR true = a true
true AND true = a b true
true OR false = a true
true AND false = a b false
false OR true = a b true
false AND true = a false
false OR false = a b false
false AND false = a false
</pre>
=={{header|Io}}==
{{trans|Ruby}}
<syntaxhighlight lang="io">a := method(bool,
writeln("a(#{bool}) called." interpolate)
bool
)
b := method(bool,
writeln("b(#{bool}) called." interpolate)
bool
)
list(true,false) foreach(avalue,
list(true,false) foreach(bvalue,
x := a(avalue) and b(bvalue)
writeln("x = a(#{avalue}) and b(#{bvalue}) is #{x}" interpolate)
writeln
y := a(avalue) or b(bvalue)
writeln("y = a(#{avalue}) or b(#{bvalue}) is #{y}" interpolate)
writeln
)
)</syntaxhighlight>
{{output}}
<pre>a(true) called.
b(true) called.
x = a(true) and b(true) is true
a(true) called.
y = a(true) or b(true) is true
a(true) called.
b(false) called.
x = a(true) and b(false) is false
a(true) called.
y = a(true) or b(false) is true
a(false) called.
x = a(false) and b(true) is false
a(false) called.
b(true) called.
y = a(false) or b(true) is true
a(false) called.
x = a(false) and b(false) is false
a(false) called.
b(false) called.
y = a(false) or b(false) is false</pre>
=={{header|J}}==
See the J wiki entry on [[j:Essays/Short Circuit Boolean|short circuit booleans]].
<syntaxhighlight lang="j">labeled=:1 :'[ smoutput@,&":~&m'
A=: 'A ' labeled
B=: 'B ' labeled
and=: ^:
or=: 2 :'u^:(-.@v)'</
{{out|Example}}
<syntaxhighlight lang="j"> (A and B) 1
B 1
A 1
Line 429 ⟶ 2,088:
B 0
A 0
0</
Note that J evaluates right-to-left.
Note also that both functions take the same argument (which might make this less than ideal for some purposes, but trying micromanage flow of control is usually counter-productive in J in much the way that global values can be counter-productive in an object oriented environment. When you are processing a large set of array data, flow of control can only make sense when it is relevant to all of the data being processed -- if you want to manage flow of control which is not relevant to the entire set of data being processed you might artificially reduce the amount of data being processed, along the lines of an SQL cursor).
=={{header|Java}}==
In Java the boolean operators <code>&&</code> and <code>||</code> are short circuit operators. The eager operator counterparts are <code>&</code> and <code>|</code>.
<
public static void main(String[] args){
System.out.println("F and F = " + (a(false) && b(false)) + "\n");
Line 461 ⟶ 2,119:
return b;
}
}</
{{out}}
<pre>a
F and F = false
Line 490 ⟶ 2,148:
a
T or T = true</pre>
=={{header|JavaScript}}==
Short-circuiting evaluation of boolean expressions has been the default since the first versions of JavaScript.
<syntaxhighlight lang="javascript">(function () {
'use strict';
function a(bool) {
console.log('a -->', bool);
return bool;
}
function b(bool) {
console.log('b -->', bool);
return bool;
}
var x = a(false) && b(true),
y = a(true) || b(false),
z = true ? a(true) : b(false);
return [x, y, z];
})();</syntaxhighlight>
The console log shows that in each case (the binding of all three values), only the left-hand part of the expression (the application of ''a(expr)'') was evaluated – ''b(expr)'' was skipped by logical short-circuiting.
{{Out}}
Console:
<pre>/* a --> false */
/* a --> true */
/* a --> true */</pre>
Return value:
<pre>[false, true, true]</pre>
=={{header|jq}}==
jq's 'and' and 'or' are short-circuit operators. The following demonstration, which follows the "awk" example above, requires a version of jq with the built-in filter 'stderr'.
<syntaxhighlight lang="jq">def a(x): " a(\(x))" | stderr | x;
def b(y): " b(\(y))" | stderr | y;
"and:", (a(true) and b(true)),
"or:", (a(true) or b(true)),
"and:", (a(false) and b(true)),
"or:", (a(false) or b(true))</syntaxhighlight>
{{out}}
<syntaxhighlight lang="sh">$ jq -r -n -f Short-circuit-evaluation.jq
and:
" a(true)"
" b(true)"
true
or:
" a(true)"
true
and:
" a(false)"
false
or:
" a(false)"
" b(true)"
true</syntaxhighlight>
=={{header|Julia}}==
Julia does have short-circuit evaluation, which works just as you expect it to:
<syntaxhighlight lang="julia">a(x) = (println("\t# Called a($x)"); return x)
b(x) = (println("\t# Called b($x)"); return x)
for i in [true,false], j in [true, false]
println("\nCalculating: x = a($i) && b($j)"); x = a(i) && b(j)
println("\tResult: x = $x")
println("\nCalculating: y = a($i) || b($j)"); y = a(i) || b(j)
println("\tResult: y = $y")
end</syntaxhighlight>
{{out}}
<pre>Calculating: x = a(true) && b(true)
# Called a(true)
# Called b(true)
Result: x = true
Calculating: y = a(true) || b(true)
# Called a(true)
Result: y = true
Calculating: x = a(true) && b(false)
# Called a(true)
# Called b(false)
Result: x = false
Calculating: y = a(true) || b(false)
# Called a(true)
Result: y = true
Calculating: x = a(false) && b(true)
# Called a(false)
Result: x = false
Calculating: y = a(false) || b(true)
# Called a(false)
# Called b(true)
Result: y = true
Calculating: x = a(false) && b(false)
# Called a(false)
Result: x = false
Calculating: y = a(false) || b(false)
# Called a(false)
# Called b(false)
Result: y = false</pre>
=={{header|Kotlin}}==
<syntaxhighlight lang="scala">// version 1.1.2
fun a(v: Boolean): Boolean {
println("'a' called")
return v
}
fun b(v: Boolean): Boolean {
println("'b' called")
return v
}
fun main(args: Array<String>){
val pairs = arrayOf(Pair(true, true), Pair(true, false), Pair(false, true), Pair(false, false))
for (pair in pairs) {
val x = a(pair.first) && b(pair.second)
println("${pair.first} && ${pair.second} = $x")
val y = a(pair.first) || b(pair.second)
println("${pair.first} || ${pair.second} = $y")
println()
}
}</syntaxhighlight>
{{out}}
<pre>
'a' called
'b' called
true && true = true
'a' called
true || true = true
'a' called
'b' called
true && false = false
'a' called
true || false = true
'a' called
false && true = false
'a' called
'b' called
false || true = true
'a' called
false && false = false
'a' called
'b' called
false || false = false
</pre>
=={{header|Lambdatalk}}==
Short-circuiting evaluation of boolean expressions has been the default since the first versions of lambdatalk.
<syntaxhighlight lang="scheme">
{def A {lambda {:bool} :bool}} -> A
{def B {lambda {:bool} :bool}} -> B
{and {A true} {B true}} -> true
{and {A true} {B false}} -> false
{and {A false} {B true}} -> false
{and {A false} {B false}} -> false
{or {A true} {B true}} -> true
{or {A true} {B false}} -> true
{or {A false} {B true}} -> true
{or {A false} {B false}} -> false
</syntaxhighlight>
Some more words about short-circuit evaluation. Lambdatalk comes with the {if "bool" then "one" else "two"} special form where "one" or "two" are not evaluated until "bool" is. This behaviour prevents useless computing and allows recursive processes. For instance, the naïve fibonacci function quickly leads to extensive computings.
<syntaxhighlight lang="scheme">
{def fib
{lambda {:n}
{if {< :n 2}
then 1
else {+ {fib {- :n 1}} {fib {- :n 2}}}}}}
-> fib
1) Using the if special form:
{if true then {+ 1 2} else {fib 29}}
-> 3 // {fib 29} is not evaluated
{if false then {+ 1 2} else {fib 29}}
-> 832040 // {fib 29} is evaluated in 5847ms
2) The if special form can't be simply replaced by a pair:
{def when {P.new {+ 1 2} {fib 29}}} // inner expressions are
{P.left {when}} -> 3 // both evaluated before
{P.right {when}} -> 832040 // and we don't want that
3) We can delay evaluation using lambdas:
{def when
{P.new {lambda {} {+ 1 2}} // will return a lambda
{lambda {} {fib 22}} }} // to be evaluated later
-> when
{{P.left {when}}} -> 3 // lambdas are evaluated
{{P.right {when}}} -> 832040 // after choice using {}
</syntaxhighlight>
=={{header|Liberty BASIC}}==
LB does not have short-circuit evaluation. Implemented with IFs.
<syntaxhighlight lang="lb">print "AND"
for i = 0 to 1
for j = 0 to 1
print "a("; i; ") AND b( "; j; ")"
res =a( i) 'call always
if res <>0 then 'short circuit if 0
res = b( j)
end if
print "=>",res
next
next
print "---------------------------------"
print "OR"
for i = 0 to 1
for j = 0 to 1
print "a("; i; ") OR b("; j; ")"
res =a( i) 'call always
if res = 0 then 'short circuit if <>0
res = b( j)
end if
print "=>", res
next
next
'----------------------------------------
function a( t)
print ,"calls func a"
a = t
end function
function b( t)
print ,"calls func b"
b = t
end function </syntaxhighlight>
{{out}}
<pre>AND
a(0) AND b( 0)
calls func a
=> 0
a(0) AND b( 1)
calls func a
=> 0
a(1) AND b( 0)
calls func a
calls func b
=> 0
a(1) AND b( 1)
calls func a
calls func b
=> 1
---------------------------------
OR
a(0) OR b(0)
calls func a
calls func b
=> 0
a(0) OR b(1)
calls func a
calls func b
=> 1
a(1) OR b(0)
calls func a
=> 1
a(1) OR b(1)
calls func a
=> 1</pre>
=={{header|LiveCode}}==
Livecode uses short-circuit evaluation.
<syntaxhighlight lang="livecode">global outcome
function a bool
put "a called with" && bool & cr after outcome
return bool
end a
function b bool
put "b called with" && bool & cr after outcome
return bool
end b
on mouseUp
local tExp
put empty into outcome
repeat for each item op in "and,or"
repeat for each item x in "true,false"
put merge("a([[x]]) [[op]] b([[x]])") into tExp
put merge(tExp && "is [[" & tExp & "]]") & cr after outcome
put merge("a([[x]]) [[op]] b([[not x]])") into tExp
put merge(tExp && "is [[" & tExp & "]]") & cr after outcome
end repeat
put cr after outcome
end repeat
put outcome
end mouseUp</syntaxhighlight>
=={{header|Logo}}==
The <code>AND</code> and <code>OR</code> predicates may take either expressions which are all evaluated beforehand, or lists which are short-circuit evaluated from left to right only until the overall value of the expression can be determined.
<syntaxhighlight lang="logo">and [notequal? :x 0] [1/:x > 3]
(or [:x < 0] [:y < 0] [sqrt :x + sqrt :y < 3])</syntaxhighlight>
=={{header|Lua}}==
<syntaxhighlight lang="lua">function a(i)
print "Function a(i) called."
return i
end
function b(i)
print "Function b(i) called."
return i
end
i = true
x = a(i) and b(i); print ""
y = a(i) or b(i); print ""
i = false
x = a(i) and b(i); print ""
y = a(i) or b(i)</syntaxhighlight>
=={{header|M2000 Interpreter}}==
<syntaxhighlight lang="m2000 interpreter">
Module Short_circuit_evaluation {
function a(a as boolean) {
=a
doc$<=format$(" Called function a({0}) -> {0}", a)+{
}
}
function b(b as boolean) {
=b
doc$<=format$(" Called function b({0}) -> {0}", b)+{
}
}
boolean T=true, F, iv, jv
variant L=(F, T), i, j
i=each(L)
global doc$ : document doc$
while i
j=each(L)
while j
(iv, jv)=(array(i), array(j))
doc$<=format$("Calculating x = a({0}) and b({1}) -> {2}", iv, jv, iv and jv)+{
}
x=if(a(iv)->b(jv), F)
doc$<=format$("x={0}", x)+{
}+ format$("Calculating y = a({0}) or b({1}) -> {2}", iv, jv, iv or jv)+{
}
y=if(a(iv)->T, b(jv))
doc$<=format$("y={0}", y)+{
}
end while
end while
clipboard doc$
report doc$
}
Short_circuit_evaluation
</syntaxhighlight>
{{out}}
<pre>
Calculating x = a(False) and b(False) -> False
Called function a(False) -> False
x=False
Calculating y = a(False) or b(False) -> False
Called function a(False) -> False
Called function b(False) -> False
y=False
Calculating x = a(False) and b(True) -> False
Called function a(False) -> False
x=False
Calculating y = a(False) or b(True) -> True
Called function a(False) -> False
Called function b(True) -> True
y=True
Calculating x = a(True) and b(False) -> False
Called function a(True) -> True
Called function b(False) -> False
x=False
Calculating y = a(True) or b(False) -> True
Called function a(True) -> True
y=True
Calculating x = a(True) and b(True) -> True
Called function a(True) -> True
Called function b(True) -> True
x=True
Calculating y = a(True) or b(True) -> True
Called function a(True) -> True
y=True
</pre>
=={{header|Maple}}==
Built-in short circuit evaluation
<syntaxhighlight lang="maple">a := proc(bool)
printf("a is called->%s\n", bool):
return bool:
end proc:
b := proc(bool)
printf("b is called->%s\n", bool):
return bool:
end proc:
for i in [true, false] do
for j in [true, false] do
printf("calculating x := a(i) and b(j)\n"):
x := a(i) and b(j):
printf("calculating x := a(i) or b(j)\n"):
y := a(i) or b(j):
od:
od:</syntaxhighlight>
{{Out|Output}}
<pre>calculating x := a(i) and b(j)
a is called->true
b is called->true
calculating x := a(i) or b(j)
a is called->true
calculating x := a(i) and b(j)
a is called->true
b is called->false
calculating x := a(i) or b(j)
a is called->true
calculating x := a(i) and b(j)
a is called->false
calculating x := a(i) or b(j)
a is called->false
b is called->true
calculating x := a(i) and b(j)
a is called->false
calculating x := a(i) or b(j)
a is called->false
b is called->false</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
Mathematica has built-in short-circuit evaluation of logical expressions.
<syntaxhighlight lang="mathematica">a[in_] := (Print["a"]; in)
b[in_] := (Print["b"]; in)
a[False] && b[True]
a[True] || b[False]</syntaxhighlight>
Evaluation of the preceding code gives:
<pre>a
False
a
True</pre>
Whereas evaluating this:
<syntaxhighlight lang="mathematica">a[True] && b[False]</syntaxhighlight>
Gives:
<pre>a
b
False</pre>
=={{header|MATLAB}} / {{header|Octave}}==
Short-circuit evalation is done in logical AND (&&) and logical OR (||) operators:
<syntaxhighlight lang="matlab"> function x=a(x)
printf('a: %i\n',x);
end;
function x=b(x)
printf('b: %i\n',x);
end;
a(1) && b(1)
a(0) && b(1)
a(1) || b(1)
a(0) || b(1)</syntaxhighlight>
{{out}}
<syntaxhighlight lang="matlab"> > a(1) && b(1);
a: 1
b: 1
> a(0) && b(1);
a: 0
> a(1) || b(1);
a: 1
> a(0) || b(1);
a: 0
b: 1</syntaxhighlight>
=={{header|Modula-2}}==
<syntaxhighlight lang="modula2">MODULE ShortCircuit;
FROM FormatString IMPORT FormatString;
FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
PROCEDURE a(v : BOOLEAN) : BOOLEAN;
VAR buf : ARRAY[0..63] OF CHAR;
BEGIN
FormatString(" # Called function a(%b)\n", buf, v);
WriteString(buf);
RETURN v
END a;
PROCEDURE b(v : BOOLEAN) : BOOLEAN;
VAR buf : ARRAY[0..63] OF CHAR;
BEGIN
FormatString(" # Called function b(%b)\n", buf, v);
WriteString(buf);
RETURN v
END b;
PROCEDURE Print(x,y : BOOLEAN);
VAR buf : ARRAY[0..63] OF CHAR;
VAR temp : BOOLEAN;
BEGIN
FormatString("a(%b) AND b(%b)\n", buf, x, y);
WriteString(buf);
temp := a(x) AND b(y);
FormatString("a(%b) OR b(%b)\n", buf, x, y);
WriteString(buf);
temp := a(x) OR b(y);
WriteLn;
END Print;
BEGIN
Print(FALSE,FALSE);
Print(FALSE,TRUE);
Print(TRUE,TRUE);
Print(TRUE,FALSE);
ReadChar
END ShortCircuit.</syntaxhighlight>
=={{header|MUMPS}}==
<
WRITE !,?10,$STACK($STACK,"PLACE")
QUIT IN
Line 514 ⟶ 2,713:
WRITE !,$SELECT(Z:"TRUE",1:"FALSE")
KILL Z
QUIT</
{{out}}
<pre>USER>D SSEVAL3^ROSETTA
1 AND 1
SSEVAL1+1^ROSETTA +3
Line 532 ⟶ 2,732:
SSEVAL1+1^ROSETTA +3
SSEVAL2+1^ROSETTA +3
TRUE</pre>
=={{header|Nanoquery}}==
Nanoquery does not short-circuit by default, so short-circuit logic functions have been implemented by nested ifs.
<syntaxhighlight lang="nanoquery">def short_and(bool1, bool2)
global a
global b
if a(bool1)
if b(bool2)
return true
else
return false
end
else
return false
end
end
def short_or(bool1, bool2)
if a(bool1)
return true
else
if b(bool2)
return true
else
return false
end
end
end
def a(bool)
println "a called."
return bool
end
def b(bool)
println "b called."
return bool
end
println "F and F = " + short_and(false, false) + "\n"
println "F or F = " + short_or(false, false) + "\n"
println "F and T = " + short_and(false, true) + "\n"
println "F or T = " + short_or(false, true) + "\n"
println "T and F = " + short_and(true, false) + "\n"
println "T or F = " + short_or(true, false) + "\n"
println "T and T = " + short_and(true, true) + "\n"
println "T or T = " + short_or(true, true) + "\n"</syntaxhighlight>
{{out}}
<pre>a called.
F and F = false
a called.
b called.
F or F = false
a called.
F and T = false
a called.
b called.
F or T = true
a called.
b called.
T and F = false
a called.
T or F = true
a called.
b called.
T and T = true
a called.
T or T = true
</pre>
=={{header|
<syntaxhighlight lang="nemerle">using System.Console;
class ShortCircuit
{
public static a(x : bool) : bool
{
WriteLine("a");
x
}
public static b(x : bool) : bool
{
WriteLine("b");
x
}
public static Main() : void
{
def t = true;
def f = false;
WriteLine("True && True : {0}", a(t) && b(t));
WriteLine("True && False: {0}", a(t) && b(f));
WriteLine("False && True : {0}", a(f) && b(t));
WriteLine("False && False: {0}", a(f) && b(f));
WriteLine("True || True : {0}", a(t) || b(t));
WriteLine("True || False: {0}", a(t) || b(f));
WriteLine("False || True : {0}", a(f) || b(t));
WriteLine("False || False: {0}", a(f) || b(f));
}
}</syntaxhighlight>
{{out}}
<syntaxhighlight lang="text">a
b
True && True : True
a
b
True && False: False
a
False && True : False
a
False && False: False
a
True || True : True
a
True || False: True
a
b
False || True : True
a
b
False || False: False</syntaxhighlight>
=={{header|NetRexx}}==
{{trans|ooRexx}}
Like [[OoRexx]], [[NetRexx]] allows a list of expressions in the condition part of <tt>If</tt> and <tt>When</tt>. Evaluation ends with the first of these expressions resulting in <tt>boolean true</tt>.
<syntaxhighlight lang="netrexx">/* NetRexx */
options replace format comments java crossref symbols nobinary
Parse Version v
Say 'Version='v
If a() | b() Then Say 'a and b are true'
If \a() | b() Then Say 'Surprise'
Else Say 'ok'
If a(), b() Then Say 'a is true'
If \a(), b() Then Say 'Surprise'
Else Say 'ok: \\a() is false'
Select
When \a(), b() Then Say 'Surprise'
Otherwise Say 'ok: \\a() is false (Select)'
End
Return
method a private static binary returns boolean
state = Boolean.TRUE.booleanValue()
Say '--a returns' state
Return state
method b private static binary returns boolean
state = Boolean.TRUE.booleanValue()
Say '--b returns' state
Return state
</syntaxhighlight>
{{out}}
<pre>
Version=NetRexx 3.03 11 Jun 2014
--a returns 1
--b returns 1
a and b are true
--a returns 1
--b returns 1
Surprise
--a returns 1
a is true
--a returns 1
--b returns 1
Surprise
--a returns 1
--b returns 1
Surprise
</pre>
=={{header|Nim}}==
Nim produces code which uses short-circuit evaluation.
<syntaxhighlight lang="nim">proc a(x): bool =
echo "a called"
result = x
proc b(x): bool =
echo "b called"
result = x
let x = a(false) and b(true) # echoes "a called"
let y = a(true) or b(true) # echoes "a called"</syntaxhighlight>
=={{header|Objeck}}==
In Objeck the Boolean operators <code>&</code> and <code>|</code> short circuit.
<syntaxhighlight lang="objeck">class ShortCircuit {
function : a(a : Bool) ~ Bool {
"a"->PrintLine();
return a;
}
function : b(b : Bool) ~ Bool {
"b"->PrintLine();
return b;
}
function : Main(args : String[]) ~ Nil {
result := a(false) & b(false);
"F and F = {$result}"->PrintLine();
result := a(false) | b(false);
"F or F = {$result}"->PrintLine();
result := a(false) & b(true);
"F and T = {$result}"->PrintLine();
result := a(false) | b(true);
"F or T = {$result}"->PrintLine();
result := a(true) & b(false);
"T and F = {$result}"->PrintLine();
result := a(true) | b(false);
"T or F = {$result}"->PrintLine();
result := a(true) & b(true);
"T and T = {$result}"->PrintLine();
result := a(true) | b(true);
"T or T = {$result}"->PrintLine();
}
}</syntaxhighlight>
=={{header|OCaml}}==
<syntaxhighlight lang="ocaml">let a r = print_endline " > function a called"; r
let b r = print_endline " > function b called"; r
Line 561 ⟶ 2,993:
print_endline "==== Testing or ====";
test_this test_or;
;;</
{{out}}
==== Testing and ====
# testing (true && true)
Line 588 ⟶ 3,018:
> function b called
=={{header|
<syntaxhighlight lang="scheme">
(define (a x)
(print " (a) => " x)
x)
(define (b x)
(print " (b) => " x)
x)
; and
(print " -- and -- ")
(for-each (lambda (x y)
(print "let's evaluate '(a as " x ") and (b as " y ")':")
(let ((out (and (a x) (b y))))
(print " result is " out)))
'(#t #t #f #f)
'(#t #f #t #f))
; or
(for-each (lambda (x y)
(print "let's evaluate '(a as " x ") or (b as " y ")':")
(let ((out (or (a x) (b y))))
(print " result is " out)))
'(#t #t #f #f)
'(#t #f #t #f))
</syntaxhighlight>
{{Out}}
<pre>
-- and --
let's evaluate '(a as #true) and (b as #true)':
(a) => #true
(b) => #true
result is #true
let's evaluate '(a as #true) and (b as #false)':
(a) => #true
(b) => #false
result is #false
let's evaluate '(a as #false) and (b as #true)':
(a) => #false
result is #false
let's evaluate '(a as #false) and (b as #false)':
(a) => #false
result is #false
-- or --
let's evaluate '(a as #true) or (b as #true)':
(a) => #true
result is #true
let's evaluate '(a as #true) or (b as #false)':
(a) => #true
result is #true
let's evaluate '(a as #false) or (b as #true)':
(a) => #false
(b) => #true
result is #true
let's evaluate '(a as #false) or (b as #false)':
(a) => #false
(b) => #false
result is #false
</pre>
=={{header|ooRexx}}==
ooRexx allows a list of expressions in the condition part of If and When.
Evaluation ends with the first of these expressions resulting in .false (or 0).
<syntaxhighlight lang="oorexx">Parse Version v
Say 'Version='v
If a() | b() Then Say 'a and b are true'
If \a() | b() Then Say 'Surprise'
Else Say 'ok'
If a(), b() Then Say 'a is true'
If \a(), b() Then Say 'Surprise'
Else Say 'ok: \a() is false'
Select
When \a(), b() Then Say 'Surprise'
Otherwise Say 'ok: \a() is false (Select)'
End
Exit
a: Say 'a returns .true'; Return .true
b: Say 'b returns 1'; Return 1
</syntaxhighlight>
{{out}}
<pre>Version=REXX-ooRexx_4.2.0(MT)_32-bit 6.04 22 Feb 2014
a returns .true
b returns 1
a and b are true
a returns .true
b returns 1
Surprise
a returns .true
b returns 1
a is true
a returns .true
ok: \a() is false
a returns .true
ok: \a() is false (Select)
</pre>
=={{header|Oz}}==
Oz' <code>andthen</code> and <code>orelse</code> operators are short-circuiting, as indicated by their name. The library functions <code>Bool.and</code> and <code>Bool.or</code> are not short-circuiting, on the other hand.
<syntaxhighlight lang="oz">declare
fun {A Answer}
AnswerS = {Value.toVirtualString Answer 1 1}
Line 641 ⟶ 3,142:
Y = {A I} orelse {B J}
end
end</
{{out}}
<syntaxhighlight lang="oz">Calculating: X = {A I} andthen {B J}
% Called function {A false} -> false
Calculating: Y = {A I} orelse {B J}
Line 666 ⟶ 3,166:
% Called function {B true} -> true
Calculating: Y = {A I} orelse {B J}
% Called function {A true} -> true</
=={{header|PARI/GP}}==
Note that <code>|</code> and <code>&</code> are deprecated versions of the GP short-circuit operators.
<syntaxhighlight lang="parigp">a(n)={
print(a"("n")");
a
Line 682 ⟶ 3,183:
and(A,B)={
a(A) && b(B)
};</
=={{header|Pascal}}==
===Standard Pascal===
Standard Pascal doesn't have native short-circuit evaluation.
<syntaxhighlight lang="pascal">program shortcircuit(output);
function a(value: boolean): boolean;
Line 704 ⟶ 3,204:
procedure scandor(value1, value2: boolean);
var
result:
begin
{and}
Line 720 ⟶ 3,220:
else
result := b(value2)
writeln(value1, ' or ', value2, ' = ', result);
end;
Line 728 ⟶ 3,228:
scandor(true, false);
scandor(true, true);
end.</syntaxhighlight>
===Turbo Pascal===
Turbo Pascal allows short circuit evaluation with a compiler switch:
<syntaxhighlight lang="pascal">program shortcircuit;
function a(value: boolean): boolean;
begin
writeln('a(', value, ')');
a := value;
end;
Line 745 ⟶ 3,243:
begin
writeln('b(', value, ')');
b := value;
end;
Line 751 ⟶ 3,249:
procedure scandor(value1, value2: boolean);
var
result:
begin
result := a(value1) and b(value);
writeln(value1, ' and ', value2, ' = ', result);
result := a(value1) or b(value2);
writeln(value1, ' or ', value2, ' = ', result);
end;
Line 765 ⟶ 3,263:
scandor(true, false);
scandor(true, true);
end.</syntaxhighlight>
===Extended Pascal===
The extended Pascal standard introduces the operators <code>and_then</code> and <code>or_else</code> for short-circuit evaluation.
<syntaxhighlight lang="pascal">program shortcircuit(output);
function a(value: boolean): boolean;
Line 801 ⟶ 3,296:
scandor(true, false);
scandor(true, true);
end.</syntaxhighlight>
Note: GNU Pascal allows <code>and then</code> and <code>or else</code> as alternatives to <code>and_then</code> and <code>or_else</code>.
=={{header|Perl}}==
Perl uses short-circuit boolean evaluation.
<syntaxhighlight lang="perl">sub a { print 'A'; return $_[0] }
sub b { print 'B'; return $_[0] }
Line 823 ⟶ 3,314:
# Test and display
test();</
{{out}}
<pre>a(1) && b(1): AB
a(1) && b(0): AB
Line 835 ⟶ 3,325:
a(0) || b(0): AB</pre>
=={{header|
In Phix all expressions are short circuited
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"a "</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">i</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"b "</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">i</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">z</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">z</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"a(%d) and b(%d) "</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">j</span><span style="color: #0000FF;">})</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" => %d\n"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">j</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">else</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"a(%d) or b(%d) "</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">j</span><span style="color: #0000FF;">})</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" => %d\n"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">or</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">j</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--</syntaxhighlight>-->
{{Out}}
<pre>
a(0) or b(0) a b => 0
a(0) or b(1) a b => 1
a(1) or b(0) a => 1
a(1) or b(1) a => 1
a(0) and b(0) a => 0
a(0) and b(1) a => 0
a(1) and b(0) a b => 0
a(1) and b(1) a b => 1
</pre>
=={{header|PicoLisp}}==
<
(msg 'a)
F )
Line 872 ⟶ 3,379:
(println I Op J '-> (Op (a I) (b J))) ) )
'(NIL NIL T T)
'(NIL T NIL T) )</
{{out}}
<pre>a
NIL and NIL -> NIL
Line 894 ⟶ 3,401:
a
T or T -> T</pre>
=={{header|Pike}}==
<syntaxhighlight lang="pike">int(0..1) a(int(0..1) i)
{
write(" a\n");
return i;
}
int(0..1) b(int(0..1) i)
{
write(" b\n");
return i;
}
foreach(({ ({ false, false }), ({ false, true }), ({ true, true }), ({ true, false }) });; array(int) args)
{
write(" %d && %d\n", @args);
a(args[0]) && b(args[1]);
write(" %d || %d\n", @args);
a(args[0]) || b(args[1]);
}</syntaxhighlight>
{{out}}
<pre>
0 && 0
a
0 || 0
a
b
0 && 1
a
0 || 1
a
b
1 && 1
a
b
1 || 1
a
1 && 0
a
b
1 || 0
a
</pre>
=={{header|PL/I}}==
<syntaxhighlight lang="pli">short_circuit_evaluation:
procedure options (main);
declare (true initial ('1'b), false initial ('0'b) ) bit (1);
declare (i, j, x, y) bit (1);
a: procedure (bv) returns (bit(1));
declare bv bit(1);
put ('Procedure ' || procedurename() || ' called.');
return (bv);
end a;
b: procedure (bv) returns (bit(1));
declare bv bit(1);
put ('Procedure ' || procedurename() || ' called.');
return (bv);
end b;
do i = true, false;
do j = true, false;
put skip(2) list ('Evaluating x with <a> with ' || i || ' and <b> with ' || j);
put skip;
if a(i) then
x = b(j);
else
x = false;
put skip data (x);
put skip(2) list ('Evaluating y with <a> with ' || i || ' and <b> with ' || j);
put skip;
if a(i) then
y = true;
else
y = b(j);
put skip data (y);
end;
end;
end short_circuit_evaluation;</syntaxhighlight>
{{out|Results}}
<pre>
Evaluating x with <a> with 1 and <b> with 1
Procedure A called. Procedure B called.
X='1'B;
Evaluating y with <a> with 1 and <b> with 1
Procedure A called.
Y='1'B;
Evaluating x with <a> with 1 and <b> with 0
Procedure A called. Procedure B called.
X='0'B;
Evaluating y with <a> with 1 and <b> with 0
Procedure A called.
Y='1'B;
Evaluating x with <a> with 0 and <b> with 1
Procedure A called.
X='0'B;
Evaluating y with <a> with 0 and <b> with 1
Procedure A called. Procedure B called.
Y='1'B;
Evaluating x with <a> with 0 and <b> with 0
Procedure A called.
X='0'B;
Evaluating y with <a> with 0 and <b> with 0
Procedure A called. Procedure B called.
Y='0'B;
</pre>
=={{header|PowerShell}}==
PowerShell handles this natively.
<syntaxhighlight lang="powershell"># Simulated fast function
function a ( [boolean]$J ) { return $J }
# Simulated slow function
function b ( [boolean]$J ) { Sleep -Seconds 2; return $J }
# These all short-circuit and do not evaluate the right hand function
( a $True ) -or ( b $False )
( a $True ) -or ( b $True )
( a $False ) -and ( b $False )
( a $False ) -and ( b $True )
# Measure of execution time
Measure-Command {
( a $True ) -or ( b $False )
( a $True ) -or ( b $True )
( a $False ) -and ( b $False )
( a $False ) -and ( b $True )
} | Select TotalMilliseconds
# These all appropriately do evaluate the right hand function
( a $False ) -or ( b $False )
( a $False ) -or ( b $True )
( a $True ) -and ( b $False )
( a $True ) -and ( b $True )
# Measure of execution time
Measure-Command {
( a $False ) -or ( b $False )
( a $False ) -or ( b $True )
( a $True ) -and ( b $False )
( a $True ) -and ( b $True )
} | Select TotalMilliseconds</syntaxhighlight>
{{out}}
<pre>True
True
False
False
TotalMilliseconds
-----------------
15.653
False
True
False
True
8012.9405</pre>
=={{header|Prolog}}==
Prolog has not functions but predicats succeed of fail.
Tested with SWI-Prolog. Should work with other dialects.
<syntaxhighlight lang="prolog">short_circuit :-
( a_or_b(true, true) -> writeln('==> true'); writeln('==> false')) , nl,
( a_or_b(true, false)-> writeln('==> true'); writeln('==> false')) , nl,
( a_or_b(false, true)-> writeln('==> true'); writeln('==> false')) , nl,
( a_or_b(false, false)-> writeln('==> true'); writeln('==> false')) , nl,
( a_and_b(true, true)-> writeln('==> true'); writeln('==> false')) , nl,
( a_and_b(true, false)-> writeln('==> true'); writeln('==> false')) , nl,
( a_and_b(false, true)-> writeln('==> true'); writeln('==> false')) , nl,
( a_and_b(false, false)-> writeln('==> true'); writeln('==> false')) .
a_and_b(X, Y) :-
format('a(~w) and b(~w)~n', [X, Y]),
( a(X), b(Y)).
a_or_b(X, Y) :-
format('a(~w) or b(~w)~n', [X, Y]),
( a(X); b(Y)).
a(X) :-
format('a(~w)~n', [X]),
X.
b(X) :-
format('b(~w)~n', [X]),
X.</syntaxhighlight>
{{out}}
<syntaxhighlight lang="prolog">?- short_circuit.
a(true) or b(true)
a(true)
==> true
a(true) or b(false)
a(true)
==> true
a(false) or b(true)
a(false)
b(true)
==> true
a(false) or b(false)
a(false)
b(false)
==> false
a(true) and b(true)
a(true)
b(true)
==> true
a(true) and b(false)
a(true)
b(false)
==> false
a(false) and b(true)
a(false)
==> false
a(false) and b(false)
a(false)
==> false
true.</syntaxhighlight>
=={{header|PureBasic}}==
Logical '''And''' & '''Or''' operators will not evaluate their right-hand expression if the outcome can be determined from the value of the left-hand expression.
<
PrintN(" # Called function a("+Str(arg)+")")
ProcedureReturn arg
Line 916 ⟶ 3,658:
Next
Next
Input()</
{{out}}
<pre>Calculating: x = a(0) And b(0)
# Called function a(0)
Line 943 ⟶ 3,686:
=={{header|Python}}==
Pythons '''and''' and '''or''' binary, infix, boolean operators will not evaluate their right-hand expression if the outcome can be determined from the value of the left-hand expression.
<
print(" # Called function a(%r) -> %r" % (answer, answer))
return answer
Line 982 ⟶ 3,725:
# Called function b(True) -> True
Calculating: y = a(i) or b(j)
# Called function a(True) -> True</
Pythons if ''expression'' can also be used to the same ends (but probably should not):
<
for j in (False, True):
print ("\nCalculating: x = a(i) and b(j) using x = b(j) if a(i) else False")
Line 1,016 ⟶ 3,758:
# Called function b(True) -> True
Calculating: y = a(i) or b(j) using y = b(j) if not a(i) else True
# Called function a(True) -> True</
=={{header|Quackery}}==
Quackery does not include short-circuit evaluation, but it can be added by use of meta-control flow words (words wrapped in reverse brackets such as <code>]done[</code>.) For details see: [https://github.com/GordonCharlton/Quackery/blob/main/The%20Book%20of%20Quackery.pdf The Book of Quackery]
The short-circuit evaluation words <code>SC-and</code> and <code>SC-or</code> defined here are used thus: <code>[ a 1 SC-and b ]</code> and <code>[ a 1 SC-or b ]</code>. These presumes that the arguments to <code>a</code> and <code>b</code> are on the stack in the order <code>j i</code>.
The <code>1</code> preceding the word is required to indicate the number of arguments that <code>b</code> would consume from the stack if it were evaluated.
Extending the task to three functions, the third, <code>c</code> also consuming one argument <code>k</code> and returning a boolean, present on the stack underneath <code>j</code> and <code>i</code> would lead to the code <code>[ a 2 SC-and b 1 SC-and c ]</code> and <code>[ a 2 SC-or b 1 SC-or c ]</code>, where the <code>2</code> is the sum of the number of arguments consumed by <code>b</code> and <code>c</code>, and the <code>1</code> is the number of arguments consumed by <code>c</code>.
<code>SC-and</code> and <code>SC-or</code> can both be used in a single short-circuit evaluation nest with three or more functions. Evaluation is strictly left to right.
Quackery does not have variables, so no assignment is shown here. Words (functions) leave their results on the stack. If desired results can be moved to ancillary stacks, which include standing-in for variables amongst their functionality.
<syntaxhighlight lang="Quackery">
[ say "evaluating "
]this[ echo cr ] is ident ( --> )
[ iff say "true"
else say "false" ] is echobool ( b --> )
[ swap iff drop done
times drop
false ]done[ ] is SC-and ( b n --> )
[ swap not iff drop done
times drop
true ]done[ ] is SC-or ( b n --> )
[ ident
2 times not ] is a ( b --> b )
[ ident
4 times not ] is b ( b --> b )
[ say "i = "
dup echobool
say " AND j = "
dup echobool
cr
[ a 1 SC-and b ]
say "result is "
echobool cr cr ] is AND-demo ( --> )
[ say "i = "
dup echobool
say " OR j = "
dup echobool
cr
[ a 1 SC-or b ]
say "result is "
echobool
cr cr ] is OR-demo ( --> )
true true AND-demo
true false AND-demo
false true AND-demo
false false AND-demo
cr
true true OR-demo
true false OR-demo
false true OR-demo
false false OR-demo</syntaxhighlight>
{{out}}
<pre>i = true AND j = true
evaluating a
evaluating b
result is true
i = false AND j = false
evaluating a
result is false
i = true AND j = true
evaluating a
evaluating b
result is false
i = false AND j = false
evaluating a
result is false
i = true OR j = true
evaluating a
result is true
i = false OR j = false
evaluating a
evaluating b
result is true
i = true OR j = true
evaluating a
result is true
i = false OR j = false
evaluating a
evaluating b
result is false</pre>
=={{header|R}}==
The builtins <tt><nowiki>&&</nowiki></tt> and <tt>||</tt> will short circuit:
{{trans|Perl}}
<syntaxhighlight lang="r">a <- function(x) {cat("a called\n"); x}
b <- function(x) {cat("b called\n"); x}
tests <- expand.grid(op=list(quote(`||`), quote(`&&`)), x=c(1,0), y=c(1,0))
invisible(apply(tests, 1, function(row) {
call <- substitute(op(a(x),b(y)), row)
cat(deparse(call), "->", eval(call), "\n\n")
}))</syntaxhighlight>
{{out}}
<syntaxhighlight lang="r">a called
a(1) || b(1) -> TRUE
a called
b called
a(1) && b(1) -> TRUE
a called
b called
a(0) || b(1) -> TRUE
a called
a(0) && b(1) -> FALSE
a called
a(1) || b(0) -> TRUE
a called
b called
a(1) && b(0) -> FALSE
a called
b called
a(0) || b(0) -> FALSE
a called
a(0) && b(0) -> FALSE </syntaxhighlight>
Because R waits until function arguments are needed before evaluating them, user-defined functions can also short circuit.
<syntaxhighlight lang="r">switchop <- function(s, x, y) {
if(s < 0) x || y
else if (s > 0) x && y
else xor(x, y)
}</syntaxhighlight>
{{out}}
<syntaxhighlight lang="r">> switchop(-1, a(1), b(1))
a called
[1] TRUE
> switchop(1, a(1), b(1))
a called
b called
[1] TRUE
> switchop(1, a(0), b(1))
a called
[1] FALSE
> switchop(0, a(0), b(1))
a called
b called
[1] TRUE</syntaxhighlight>
=={{header|Racket}}==
<syntaxhighlight lang="racket">#lang racket
(define (a x)
(display (~a "a:" x " "))
x)
(define (b x)
(display (~a "b:" x " "))
x)
(for* ([x '(#t #f)]
[y '(#t #f)])
(displayln `(and (a ,x) (b ,y)))
(and (a x) (b y))
(newline)
(displayln `(or (a ,x) (b ,y)))
(or (a x) (b y))
(newline))</syntaxhighlight>
{{out}}
<pre>
(and (a #t) (b #t))
a:#t b:#t
(or (a #t) (b #t))
a:#t
(and (a #t) (b #f))
a:#t b:#f
(or (a #t) (b #f))
a:#t
(and (a #f) (b #t))
a:#f
(or (a #f) (b #t))
a:#f b:#t
(and (a #f) (b #f))
a:#f
(or (a #f) (b #f))
a:#f b:#f
</pre>
=={{header|Raku}}==
(formerly Perl 6)
{{Works with|rakudo|2018.03}}
<syntaxhighlight lang="raku" line>use MONKEY-SEE-NO-EVAL;
sub a ($p) { print 'a'; $p }
sub b ($p) { print 'b'; $p }
for 1, 0 X 1, 0 -> ($p, $q) {
for '&&', '||' -> $op {
my $s = "a($p) $op b($q)";
print "$s: ";
EVAL $s;
print "\n";
}
}</syntaxhighlight>
{{out}}
<pre>a(1) && b(1): ab
a(1) || b(1): a
a(1) && b(0): ab
a(1) || b(0): a
a(0) && b(1): a
a(0) || b(1): ab
a(0) && b(0): a
a(0) || b(0): ab</pre>
=={{header|REXX}}==
The REXX language doesn't have native short circuits (it's specifically mentioned in the
language specifications that
<br>short-circuiting is '''not''' supported).
<syntaxhighlight lang="rexx">/*REXX programs demonstrates short─circuit evaluation testing (in an IF statement).*/
parse arg LO HI . /*obtain optional arguments from the CL*/
if LO=='' | LO=="," then LO= -2 /*Not specified? Then use the default.*/
if HI=='' | HI=="," then HI= 2 /* " " " " " " */
do j=LO to HI /*process from the low to the high.*/
x=a(j) & b(j) /*compute function A and function B */
y=a(j) | b(j) /* " " " or " " */
if \y then y=b(j) /* " " B (for negation).*/
say copies('═', 30) ' x=' || x ' y='y ' j='j
say
end /*j*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
a: say ' A entered with:' arg(1); return abs( arg(1) // 2) /*1=odd, 0=even */
b: say ' B entered with:' arg(1); return arg(1) < 0 /*1=neg, 0=if not*/</syntaxhighlight>
{{out|output|text= when using the default inputs:}}
<pre>
B entered with: -2
A entered with: -2
B entered with: -2
A entered with: -2
══════════════════════════════ x=0 y=1 j=-2
B entered with: -1
A entered with: -1
B entered with: -1
A entered with: -1
══════════════════════════════ x=1 y=1 j=-1
B entered with: 0
A entered with: 0
B entered with: 0
A entered with: 0
B entered with: 0
══════════════════════════════ x=0 y=0 j=0
B entered with: 1
A entered with: 1
B entered with: 1
A entered with: 1
══════════════════════════════ x=0 y=1 j=1
B entered with: 2
A entered with: 2
B entered with: 2
A entered with: 2
B entered with: 2
══════════════════════════════ x=0 y=0 j=2
</pre>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
# Project : Short-circuit evaluation
for k = 1 to 2
word = ["AND","OR"]
see "========= " + word[k] + " ==============" + nl
for i = 0 to 1
for j = 0 to 1
see "a(" + i + ") " + word[k] +" b(" + j + ")" + nl
res =a(i)
if word[k] = "AND" and res != 0
res = b(j)
ok
if word[k] = "OR" and res = 0
res = b(j)
ok
next
next
next
func a(t)
see char(9) + "calls func a" + nl
a = t
return a
func b(t)
see char(9) + "calls func b" + nl
b = t
return b
</syntaxhighlight>
Output:
<pre>
========= AND ==============
a(0) AND b(0)
calls func a
a(0) AND b(1)
calls func a
a(1) AND b(0)
calls func a
calls func b
a(1) AND b(1)
calls func a
calls func b
========= OR ==============
a(0) OR b(0)
calls func a
calls func b
a(0) OR b(1)
calls func a
calls func b
a(1) OR b(0)
calls func a
a(1) OR b(1)
calls func a
</pre>
=={{header|Ruby}}==
Binary operators are short-circuiting. Demonstration code:
<syntaxhighlight lang="ruby">def a( bool )
puts "a( #{bool} ) called"
bool
end
def b( bool )
puts "b( #{bool} ) called"
bool
end
[true, false].each do |a_val|
[true, false].each do |b_val|
puts "a( #{a_val} ) and b( #{b_val} ) is #{a( a_val ) and b( b_val )}."
puts
puts "a( #{a_val} ) or b( #{b_val} ) is #{a( a_val) or b( b_val )}."
puts
end
end</syntaxhighlight>
{{out}}
<pre>
a( true ) called
b( true ) called
a( true ) and b( true ) is true.
a( true ) called
a( true ) or b( true ) is true.
a( true ) called
b( false ) called
a( true ) and b( false ) is false.
a( true ) called
a( true ) or b( false ) is true.
a( false ) called
a( false ) and b( true ) is false.
a( false ) called
b( true ) called
a( false ) or b( true ) is true.
a( false ) called
a( false ) and b( false ) is false.
a( false ) called
b( false ) called
a( false ) or b( false ) is false.
</pre>
=={{header|Run BASIC}}==
<syntaxhighlight lang="runbasic">for k = 1 to 2
ao$ = word$("AND,OR",k,",")
print "========= ";ao$;" =============="
for i = 0 to 1
for j = 0 to 1
print "a("; i; ") ";ao$;" b("; j; ")"
res =a(i) 'call always
'print res;"<===="
if ao$ = "AND" and res <> 0 then res = b(j)
if ao$ = "OR" and res = 0 then res = b(j)
next
next
next k
end
function a( t)
print chr$(9);"calls func a"
a = t
end function
function b( t)
print chr$(9);"calls func b"
b = t
end function</syntaxhighlight>
<pre>========= AND ==============
a(0) AND b(0)
calls func a
a(0) AND b(1)
calls func a
a(1) AND b(0)
calls func a
calls func b
a(1) AND b(1)
calls func a
calls func b
========= OR ==============
a(0) OR b(0)
calls func a
calls func b
a(0) OR b(1)
calls func a
calls func b
a(1) OR b(0)
calls func a
a(1) OR b(1)
calls func a</pre>
=={{header|Rust}}==
<syntaxhighlight lang="rust">fn a(foo: bool) -> bool {
println!("a");
foo
}
fn b(foo: bool) -> bool {
println!("b");
foo
}
fn main() {
for i in vec![true, false] {
for j in vec![true, false] {
println!("{} and {} == {}", i, j, a(i) && b(j));
println!("{} or {} == {}", i, j, a(i) || b(j));
println!();
}
}
}</syntaxhighlight>
{{out}}
<pre>
a
b
true and true == true
a
true or true == true
a
b
true and false == false
a
true or false == true
a
false and true == false
a
b
false or true == true
a
false and false == false
a
b
false or false == false
</pre>
=={{header|Sather}}==
<syntaxhighlight lang="sather">class MAIN is
a(v:BOOL):BOOL is
#OUT + "executing a\n";
return v;
end;
b(v:BOOL):BOOL is
#OUT + "executing b\n";
return v;
end;
main is
x:BOOL;
x := a(false) and b(true);
#OUT + "F and T = " + x + "\n\n";
x := a(true) or b(true);
#OUT + "T or T = " + x + "\n\n";
x := a(true) and b(false);
#OUT + "T and T = " + x + "\n\n";
x := a(false) or b(true);
#OUT + "F or T = " + x + "\n\n";
end;
end;</syntaxhighlight>
=={{header|Scala}}==
<syntaxhighlight lang="scala">object ShortCircuit {
def a(b:Boolean)={print("Called A=%5b".format(b));b}
def b(b:Boolean)={print(" -> B=%5b".format(b));b}
def main(args: Array[String]): Unit = {
val boolVals=List(false,true)
for(aa<-boolVals; bb<-boolVals){
print("\nTesting A=%5b AND B=%5b -> ".format(aa, bb))
a(aa) && b(bb)
}
for(aa<-boolVals; bb<-boolVals){
print("\nTesting A=%5b OR B=%5b -> ".format(aa, bb))
a(aa) || b(bb)
}
println
}
}</syntaxhighlight>
{{out}}
<pre>Testing A=false AND B=false -> Called A=false
Testing A=false AND B= true -> Called A=false
Testing A= true AND B=false -> Called A= true -> B=false
Testing A= true AND B= true -> Called A= true -> B= true
Testing A=false OR B=false -> Called A=false -> B=false
Testing A=false OR B= true -> Called A=false -> B= true
Testing A= true OR B=false -> Called A= true
Testing A= true OR B= true -> Called A= true</pre>
=={{header|Scheme}}==
<
(display "a\n")
x)
Line 1,053 ⟶ 4,341:
a
b
</syntaxhighlight>
=={{header|
<syntaxhighlight lang="seed7">$ include "seed7_05.s7i";
const func boolean: a (in boolean: aBool) is func
result
var boolean: result is FALSE;
begin
writeln("a");
result := aBool;
end func;
const func boolean: b (in boolean: aBool) is func
result
var boolean: result is FALSE;
begin
writeln("b");
result := aBool;
end func;
const proc: test (in boolean: param1, in boolean: param2) is func
begin
writeln(param1 <& " and " <& param2 <& " = " <& a(param1) and b(param2));
writeln(param1 <& " or " <& param2 <& " = " <& a(param1) or b(param2));
end func;
const proc: main is func
begin
test(FALSE, FALSE);
test(FALSE, TRUE);
test(TRUE, FALSE);
test(TRUE, TRUE);
end func;</syntaxhighlight>
{{out}}
<pre>
a
FALSE and FALSE = FALSE
a
b
FALSE or FALSE = FALSE
a
FALSE and TRUE = FALSE
a
b
FALSE or TRUE = TRUE
a
b
TRUE and FALSE = FALSE
a
TRUE or FALSE = TRUE
a
b
TRUE and TRUE = TRUE
a
TRUE or TRUE = TRUE
</pre>
=={{header|Sidef}}==
<syntaxhighlight lang="ruby">func a(bool) { print 'A'; return bool }
func b(bool) { print 'B'; return bool }
# Test-driver
func test() {
for op in ['&&', '||'] {
for x,y in [[1,1],[1,0],[0,1],[0,0]] {
"a(%s) %s b(%s): ".printf(x, op, y)
eval "a(Bool(x)) #{op} b(Bool(y))"
print "\n"
}
}
}
# Test and display
test()</syntaxhighlight>
{{out}}
<pre>a(1) && b(1): AB
a(1) && b(0): AB
a(0) && b(1): A
a(0) && b(0): A
a(1) || b(1): A
a(1) || b(0): A
a(0) || b(1): AB
a(0) || b(0): AB</pre>
=={{header|Simula}}==
<syntaxhighlight lang="simula">BEGIN
BOOLEAN PROCEDURE A(BOOL); BOOLEAN BOOL;
BEGIN OUTCHAR('A'); A := BOOL;
END A;
BOOLEAN PROCEDURE B(BOOL); BOOLEAN BOOL;
BEGIN OUTCHAR('B'); B := BOOL;
END B;
PROCEDURE OUTBOOL(BOOL); BOOLEAN BOOL;
OUTCHAR(IF BOOL THEN 'T' ELSE 'F');
PROCEDURE TEST;
BEGIN
PROCEDURE ANDTEST;
BEGIN
BOOLEAN X, Y, Z;
FOR X := TRUE, FALSE DO
FOR Y := TRUE, FALSE DO
BEGIN
OUTTEXT("A("); OUTBOOL(X);
OUTTEXT(") AND ");
OUTTEXT("B("); OUTBOOL(Y);
OUTTEXT("): ");
Z := A(X) AND THEN B(Y);
OUTIMAGE;
END;
END ANDTEST;
PROCEDURE ORTEST;
BEGIN
BOOLEAN X, Y, Z;
FOR X := TRUE, FALSE DO
FOR Y := TRUE, FALSE DO
BEGIN
OUTTEXT("A("); OUTBOOL(X);
OUTTEXT(") OR ");
OUTTEXT("B("); OUTBOOL(Y);
OUTTEXT("): ");
Z := A(X) OR ELSE B(Y);
OUTIMAGE;
END;
END ORTEST;
ANDTEST;
ORTEST;
END TEST;
TEST;
END.
</syntaxhighlight>
{{out}}
<pre>
A(T) AND B(T): AB
A(T) AND B(F): AB
A(F) AND B(T): A
A(F) AND B(F): A
A(T) OR B(T): A
A(T) OR B(F): A
A(F) OR B(T): AB
A(F) OR B(F): AB
</pre>
=={{header|Smalltalk}}==
{{works with|GNU Smalltalk}}
The <code>and:</code> <code>or:</code> selectors are shortcircuit selectors but in order to avoid evaluation of the second operand, it must be a block: <code>a and: [ code ]</code> will evaluate the code only if a is true. On the other hand, <code>a and: b</code>, where b is an expression (not a block), behaves like the non-shortcircuit and (&). (Same speech for or |)
<syntaxhighlight lang="smalltalk">Smalltalk at: #a put: nil.
Smalltalk at: #b put: nil.
a := [:x| 'executing a' displayNl. x].
b := [:x| 'executing b' displayNl. x].
('false and false = %1' %
{ (a value: false) and: [ b value: false ] })
displayNl.
('true or false = %1' %
{ (a value: true) or: [ b value: false ] })
displayNl.
('false or true = %1' %
{ (a value: false) or: [ b value: true ] })
displayNl.
('true and false = %1' %
{ (a value: true) and: [ b value: false ] })
displayNl.</syntaxhighlight>
=={{header|SNOBOL4}}==
Because of its unique success/failure model of flow control, Snobol does not use standard boolean operators or assignment. However, in &fullscan mode Snobol exhibits short-circuit boolean behavior in pattern matches, with concatenation " " functioning as logical AND, and alternation " | " as logical OR.
The test statements below use a pattern constructed from the functions a( ) and b( ) and match it to the null string with deferred evaluation. This idiom allows the functions to self-report the expected short-circuit patterns.
<syntaxhighlight lang="snobol4"> define('a(val)') :(a_end)
a out = 'A '
eq(val,1) :s(return)f(freturn)
Line 1,086 ⟶ 4,546:
out = 'F or T: '; null ? *a(0) | *b(1); nl()
out = 'F or F: '; null ? *a(0) | *b(0); nl()
end</
{{out}}
<pre>T and T: A B
T and F: A B
Line 1,098 ⟶ 4,557:
F or T: A B
F or F: A B</pre>
=={{header|Standard ML}}==
{{trans|OCaml}}
<syntaxhighlight lang="sml">fun a r = ( print " > function a called\n"; r )
fun b r = ( print " > function b called\n"; r )
fun test_and b1 b2 = (
print ("# testing (" ^ Bool.toString b1 ^ " andalso " ^ Bool.toString b2 ^ ")\n");
ignore (a b1 andalso b b2) )
fun test_or b1 b2 = (
print ("# testing (" ^ Bool.toString b1 ^ " orelse " ^ Bool.toString b2 ^ ")\n");
ignore (a b1 orelse b b2) )
fun test_this test = (
test true true;
test true false;
test false true;
test false false )
;
print "==== Testing and ====\n";
test_this test_and;
print "==== Testing or ====\n";
test_this test_or;</syntaxhighlight>
{{out}}
==== Testing and ====
# testing (true andalso true)
> function a called
> function b called
# testing (true andalso false)
> function a called
> function b called
# testing (false andalso true)
> function a called
# testing (false andalso false)
> function a called
==== Testing or ====
# testing (true orelse true)
> function a called
# testing (true orelse false)
> function a called
# testing (false orelse true)
> function a called
> function b called
# testing (false orelse false)
> function a called
> function b called
=={{header|Stata}}==
Stata always evaluates both arguments of operators & and |. Here is a solution with '''if''' statements.
<syntaxhighlight lang="stata">function a(x) {
printf(" a")
return(x)
}
function b(x) {
printf(" b")
return(x)
}
function call(i, j) {
printf("and:")
x = a(i)
if (x) {
x = b(j)
}
printf("\nor:")
y = a(i)
if (!y) {
y = b(j)
}
printf("\n")
return((x,y))
}</syntaxhighlight>
'''Example'''
<syntaxhighlight lang="stata">: call(0,1)
and: a
or: a b
1 2
+---------+
1 | 0 1 |
+---------+
: call(1,1)
and: a b
or: a
1 2
+---------+
1 | 1 1 |
+---------+</syntaxhighlight>
=={{header|Swift}}==
Short circuit operators are <nowiki>&&</nowiki> and ||.
<syntaxhighlight lang="swift">func a(v: Bool) -> Bool {
print("a")
return v
}
func b(v: Bool) -> Bool {
print("b")
return v
}
func test(i: Bool, j: Bool) {
println("Testing a(\(i)) && b(\(j))")
print("Trace: ")
println("\nResult: \(a(i) && b(j))")
println("Testing a(\(i)) || b(\(j))")
print("Trace: ")
println("\nResult: \(a(i) || b(j))")
println()
}
test(false, false)
test(false, true)
test(true, false)
test(true, true)</syntaxhighlight>
{{out}}
<pre>
Testing a(false) && b(false)
Trace: a
Result: false
Testing a(false) || b(false)
Trace: ab
Result: false
Testing a(false) && b(true)
Trace: a
Result: false
Testing a(false) || b(true)
Trace: ab
Result: true
Testing a(true) && b(false)
Trace: ab
Result: false
Testing a(true) || b(false)
Trace: a
Result: true
Testing a(true) && b(true)
Trace: ab
Result: true
Testing a(true) || b(true)
Trace: a
Result: true
</pre>
=={{header|Tcl}}==
The <code>&&</code> and <code>||</code> in the <code>expr</code> command support short-circuit evaluation. It is recommended that you always put expressions in braces so that and command or variable substitutions are applied at the right time rather than before the expression is evaluated at all. (Indeed, it is recommended that you do that anyway as unbraced expressions cannot be efficiently compiled.)
<
proc tcl::mathfunc::a boolean {
puts "a($boolean) called"
Line 1,119 ⟶ 4,732:
puts ""; # Blank line for clarity
}
}</
<pre>
a(false) called
Line 1,147 ⟶ 4,760:
</pre>
=={{header|TXR}}==
<syntaxhighlight lang="txr">@(define a (x out))
@ (output)
a (@x) called
@ (end)
@ (bind out x)
@(end)
@(define b (x out))
@ (output)
b (@x) called
@ (end)
@ (bind out x)
@(end)
@(define short_circuit_demo (i j))
@ (output)
a(@i) and b(@j):
@ (end)
@ (maybe)
@ (a i "1")
@ (b j "1")
@ (end)
@ (output)
a(@i) or b(@j):
@ (end)
@ (cases)
@ (a i "1")
@ (or)
@ (b j "1")
@ (or)
@ (accept)
@ (end)
@(end)
@(short_circuit_demo "0" "0")
@(short_circuit_demo "0" "1")
@(short_circuit_demo "1" "0")
@(short_circuit_demo "1" "1")</syntaxhighlight>
{{out|Run}}
<pre>$ txr short-circuit-bool.txr
a(0) and b(0):
a (0) called
a(0) or b(0):
a (0) called
b (0) called
a(0) and b(1):
a (0) called
a(0) or b(1):
a (0) called
b (1) called
a(1) and b(0):
a (1) called
b (0) called
a(1) or b(0):
a (1) called
a(1) and b(1):
a (1) called
b (1) called
a(1) or b(1):
a (1) called</pre>
The <code>a</code> and <code>b</code> functions are defined such that the second parameter is intended to be an unbound variable. When the function binds <code>out</code>, that value propagates back to the unbound variable at the call site. But the way calls works in this language allows us to specify a value instead such as <code>"1"</code>. So now the directive <code>@(bind out x)</code> performs unification instead: if <code>x</code> doesn't match <code>"1"</code>, the function fails, otherwise it succeeds.
So simply by placing two calls consecutively, we get a short circuting conjunction. The second will not execute if the first one fails.
Short-circuiting disjunction is provided by <code>@(cases)</code>.
The <code>@(maybe)</code> construct stops failure from propagating from the enclosed subquery. The <code>@(accept)</code> directive will bail out of the closest enclosing anonymous block (the function body) with a success. It prevents the <code>@(cases)</code> from failing the function if neither case is successful.
=={{header|UNIX Shell}}==
The ''&&'' and ''||'' operators use the exit status of each command. The ''true'' and ''false'' commands convert a string to an exit status; our code ''&& x=true || x=false'' converts an exit status to a string.
{{works with|Bourne Shell}}
<syntaxhighlight lang="bash">a() {
echo "Called a $1"
"$1"
}
b() {
echo "Called b $1"
"$1"
}
for i in false true; do
for j in false true; do
a $i && b $j && x=true || x=false
echo " $i && $j is $x"
a $i || b $j && y=true || y=false
echo " $i || $j is $y"
done
done</syntaxhighlight>
The output reveals that <nowiki>&&</nowiki> and || have short-circuit evaluation.
<pre>Called a false
false && false is false
Called a false
Called b false
false || false is false
Called a false
false && true is false
Called a false
Called b true
false || true is true
Called a true
Called b false
true && false is false
Called a true
true || false is true
Called a true
Called b true
true && true is true
Called a true
true || true is true</pre>
==={{header|C Shell}}===
Between commands, ''&&'' and ''||'' have short-circuit evaluation. (The aliases for ''a'' and ''b'' must expand to a single command; these aliases expand to an ''eval'' command.)
<syntaxhighlight lang="csh">alias a eval \''echo "Called a \!:1"; "\!:1"'\'
alias b eval \''echo "Called b \!:1"; "\!:1"'\'
foreach i (false true)
foreach j (false true)
a $i && b $j && set x=true || set x=false
echo " $i && $j is $x"
a $i || b $j && set x=true || set x=false
echo " $i || $j is $x"
end
end</syntaxhighlight>
Inside expressions, ''&&'' and ''||'' can short circuit some commands, but cannot prevent substitutions.
<syntaxhighlight lang="csh"># Succeeds, only prints "ok".
if ( 1 || { echo This command never runs. } ) echo ok
# Fails, aborts shell with "bad: Undefined variable".
if ( 1 || $bad ) echo ok
# Prints "error", then "ok".
if ( 1 || `echo error >/dev/stderr` ) echo ok</syntaxhighlight>
=={{header|VBA}}==
<syntaxhighlight lang="vb">Private Function a(i As Variant) As Boolean
Debug.Print "a: "; i = 1,
a = i
End Function
Private Function b(j As Variant) As Boolean
Debug.Print "b: "; j = 1;
b = j
End Function
Public Sub short_circuit()
Dim x As Boolean, y As Boolean
'Dim p As Boolean, q As Boolean
Debug.Print "=====AND=====" & vbCrLf
For p = 0 To 1
For q = 0 To 1
If a(p) Then
x = b(q)
End If
Debug.Print " = x"
Next q
Debug.Print
Next p
Debug.Print "======OR=====" & vbCrLf
For p = 0 To 1
For q = 0 To 1
If Not a(p) Then
x = b(q)
End If
Debug.Print " = x"
Next q
Debug.Print
Next p
Debug.Print
End Sub
</syntaxhighlight>{{out}}<pre>=====AND=====
a: Onwaar = x
a: Onwaar = x
a: Waar b: Onwaar = x
a: Waar b: Waar = x
======OR=====
a: Onwaar b: Onwaar = x
a: Onwaar b: Waar = x
a: Waar = x
a: Waar = x</pre>
=={{header|Visual Basic .NET}}==
{{trans|c++}}
<syntaxhighlight lang="vbnet">Module Module1
Function A(v As Boolean) As Boolean
Console.WriteLine("a")
Return v
End Function
Function B(v As Boolean) As Boolean
Console.WriteLine("b")
Return v
End Function
Sub Test(i As Boolean, j As Boolean)
Console.WriteLine("{0} and {1} = {2} (eager evaluation)", i, j, A(i) And B(j))
Console.WriteLine("{0} or {1} = {2} (eager evaluation)", i, j, A(i) Or B(j))
Console.WriteLine("{0} and {1} = {2} (lazy evaluation)", i, j, A(i) AndAlso B(j))
Console.WriteLine("{0} or {1} = {2} (lazy evaluation)", i, j, A(i) OrElse B(j))
Console.WriteLine()
End Sub
Sub Main()
Test(False, False)
Test(False, True)
Test(True, False)
Test(True, True)
End Sub
End Module</syntaxhighlight>
{{out}}
<pre>a
b
False and False = False (eager evaluation)
a
b
False or False = False (eager evaluation)
a
False and False = False (lazy evaluation)
a
b
False or False = False (lazy evaluation)
a
b
False and True = False (eager evaluation)
a
b
False or True = True (eager evaluation)
a
False and True = False (lazy evaluation)
a
b
False or True = True (lazy evaluation)
a
b
True and False = False (eager evaluation)
a
b
True or False = True (eager evaluation)
a
b
True and False = False (lazy evaluation)
a
True or False = True (lazy evaluation)
a
b
True and True = True (eager evaluation)
a
b
True or True = True (eager evaluation)
a
b
True and True = True (lazy evaluation)
a
True or True = True (lazy evaluation)</pre>
=={{header|Visual FoxPro}}==
<syntaxhighlight lang="vfp">
*!* Visual FoxPro natively supports short circuit evaluation
CLEAR
CREATE CURSOR funceval(arg1 L, arg2 L, operation V(3), result L, calls V(10))
*!* Conjunction
INSERT INTO funceval (arg1, arg2, operation) VALUES (.F., .F., "AND")
REPLACE result WITH (a(arg1) AND b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.F., .T., "AND")
REPLACE result WITH (a(arg1) AND b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.T., .F., "AND")
REPLACE result WITH (a(arg1) AND b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.T., .T., "AND")
REPLACE result WITH (a(arg1) AND b(arg2))
*!* Disjunction
INSERT INTO funceval (arg1, arg2, operation) VALUES (.F., .F., "OR")
REPLACE result WITH (a(arg1) OR b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.F., .T., "OR")
REPLACE result WITH (a(arg1) OR b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.T., .F., "OR")
REPLACE result WITH (a(arg1) OR b(arg2))
INSERT INTO funceval (arg1, arg2, operation) VALUES (.T., .T., "OR")
REPLACE result WITH (a(arg1) OR b(arg2))
GO TOP
_VFP.DataToClip("funceval", 8, 3)
FUNCTION a(v As Boolean) As Boolean
REPLACE calls WITH "a()"
RETURN v
ENDFUNC
FUNCTION b(v As Boolean) As Boolean
REPLACE calls WITH calls + ", b()"
RETURN v
ENDFUNC
</syntaxhighlight>
{{out}}
<pre>
Arg1 Arg2 Operation Result Calls
F F AND F a()
F T AND F a()
T F AND F a(), b()
T T AND T a(), b()
F F OR F a(), b()
F T OR T a(), b()
T F OR T a()
T T OR T a()
</pre>
=={{header|V (Vlang)}}==
<syntaxhighlight lang="Zig">
fn main() {
test_me(false, false)
test_me(false, true)
test_me(true, false)
test_me(true, true)
}
fn a(v bool) bool {
print("a")
return v
}
fn b(v bool) bool {
print("b")
return v
}
fn test_me(i bool, j bool) {
println("Testing a(${i}) && b(${j})")
print("Trace: ")
println("\nResult: ${a(i) && b(j)}")
println("Testing a(${i})} || b(${j})")
print("Trace: ")
println("\nResult: ${a(i) || b(j)}")
println("")
}
</syntaxhighlight>
{{out}}
<pre>
Testing a(false) && b(false)
Trace: a
Result: false
Testing a(false)} || b(false)
Trace: ab
Result: false
Testing a(false) && b(true)
Trace: a
Result: false
Testing a(false)} || b(true)
Trace: ab
Result: true
Testing a(true) && b(false)
Trace: ab
Result: false
Testing a(true)} || b(false)
Trace: a
Result: true
Testing a(true) && b(true)
Trace: ab
Result: true
Testing a(true)} || b(true)
Trace: a
Result: true
</pre>
=={{header|Wren}}==
Wren has the '''&&''' and '''||''' short-circuiting operators found in many C family languages.
<syntaxhighlight lang="wren">var a = Fn.new { |bool|
System.print(" a called")
return bool
}
var b = Fn.new { |bool|
System.print(" b called")
return bool
}
var bools = [ [true, true], [true, false], [false, true], [false, false] ]
for (bool in bools) {
System.print("a = %(bool[0]), b = %(bool[1]), op = && :")
a.call(bool[0]) && b.call(bool[1])
System.print()
}
for (bool in bools) {
System.print("a = %(bool[0]), b = %(bool[1]), op = || :")
a.call(bool[0]) || b.call(bool[1])
System.print()
}</syntaxhighlight>
{{out}}
<pre>
a = true, b = true, op = && :
a called
b called
a = true, b = false, op = && :
a called
b called
a = false, b = true, op = && :
a called
a = false, b = false, op = && :
a called
a = true, b = true, op = || :
a called
a = true, b = false, op = || :
a called
a = false, b = true, op = || :
a called
b called
a = false, b = false, op = || :
a called
b called
</pre>
=={{header|zkl}}==
<syntaxhighlight lang="zkl">fcn a(b){self.fcn.println(b); b}
fcn b(b){self.fcn.println(b); b}</syntaxhighlight>
{{out}}
<pre>
a(True) or b(True) //-->Fcn(a)True, True
a(False) or b(True) //-->Fcn(a)False, Fcn(b)True, True
a(False) or b(False) //-->Fcn(a)False, Fcn(b)False, False
a(True) and b(True) //-->Fcn(a)True, Fcn(b)True, True
a(True) and b(False) //-->Fcn(a)True, Fcn(b)False, False
a(False) and b(True) //-->Fcn(a)False, False
</pre>
{{omit from|GUISS}}
{{omit from|ZX Spectrum Basic|does not short circuit}}
| |||