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Mutual recursion: Difference between revisions

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Mutual recursion (view source)

Revision as of 16:55, 14 March 2024

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m(0 - 19): 0, 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, 10, 11, 11, 12
</pre>
 
=={{header|ABC}}==
<syntaxhighlight lang="ABC">HOW TO RETURN f n:
IF n=0: RETURN 1
RETURN n - m f (n-1)
 
HOW TO RETURN m n:
IF n=0: RETURN 0
RETURN n - f m (n-1)
 
WRITE "F:"
FOR n IN {0..15}: WRITE f n
WRITE /
 
WRITE "M:"
FOR n IN {0..15}: WRITE m n
WRITE /</syntaxhighlight>
{{out}}
<pre>F: 1 1 2 2 3 3 4 5 5 6 6 7 8 8 9 9
M: 0 0 1 2 2 3 4 4 5 6 6 7 7 8 9 9</pre>
 
=={{header|ACL2}}==
Line 890 ⟶ 910:
p 0.to(20).map! { n | female n }
p 0.to(20).map! { n | male n }</syntaxhighlight>
 
=={{header|Bruijn}}==
Normally it's not possible to call functions before they are defined. We can still induce mutual recursion using its [[Variadic_fixed-point_combinator|variadic fixed-point combinator]].
<syntaxhighlight lang="bruijn">
:import std/Combinator .
:import std/Number .
:import std/List .
 
f' [[[=?0 (+1) (0 - (1 (2 --0)))]]]
 
m' [[[=?0 (+0) (0 - (2 (1 --0)))]]]
 
f ^(y* (f' : {}m'))
 
m _(y* (f' : {}m'))
 
:test ((f (+0)) =? (+1)) ([[1]])
:test ((m (+0)) =? (+0)) ([[1]])
:test ((f (+4)) =? (+3)) ([[1]])
:test ((m (+4)) =? (+2)) ([[1]])
:test ((f (+15)) =? (+9)) ([[1]])
:test ((m (+15)) =? (+9)) ([[1]])
</syntaxhighlight>
 
=={{header|C}}==
Line 1,278 ⟶ 1,321:
 
But you don't have to worry about that to use it.
 
=={{header|EasyLang}}==
<syntaxhighlight>
funcdecl M n .
func F n .
if n = 0
return 1
.
return n - M F (n - 1)
.
func M n .
if n = 0
return 0
.
return n - F M (n - 1)
.
for i = 0 to 15
write F i & " "
.
print ""
for i = 0 to 15
write M i & " "
.
</syntaxhighlight>
 
=={{header|Eiffel}}==
Line 1,337 ⟶ 1,404:
=={{header|Elena}}==
{{trans|Smalltalk}}
ELENA 46.x :
<syntaxhighlight lang="elena">import extensions;
import system'collections;
Line 1,349 ⟶ 1,416:
var rb := new ArrayList();
for(int i := 0,; i <= 19,; i += 1)
{
ra.append(F(i));
Line 1,613 ⟶ 1,680:
=={{header|Fōrmulæ}}==
 
{{FormulaeEntry|page=https://formulae.org/?script=examples/Mutual_recursion}}
Fōrmulæ programs are not textual, visualization/edition of programs is done showing/manipulating structures but not text. Moreover, there can be multiple visual representations of the same program. Even though it is possible to have textual representation &mdash;i.e. XML, JSON&mdash; they are intended for storage and transfer purposes more than visualization and edition.
 
'''Solution'''
Programs in Fōrmulæ are created/edited online in its [https://formulae.org website], However they run on execution servers. By default remote servers are used, but they are limited in memory and processing power, since they are intended for demonstration and casual use. A local server can be downloaded and installed, it has no limitations (it runs in your own computer). Because of that, example programs can be fully visualized and edited, but some of them will not run if they require a moderate or heavy computation/memory resources, and no local server is being used.
 
[[File:Fōrmulæ - Mutual recursion 01.png]]
In '''[https://formulae.org/?example=Mutual_recursion this]''' page you can see the program(s) related to this task and their results.
 
[[File:Fōrmulæ - Mutual recursion 02.png]]
 
[[File:Fōrmulæ - Mutual recursion 03.png]]
 
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">
def fn F( n as long ) as long
def fn M( n as long ) as long
 
local fn F( n as long ) as long
long result
if n == 0 then exit fn = 1
result = n - fn M( fn F( n-1 ) )
end fn = result
 
local fn M( n as long ) as long
long result
if n == 0 then exit fn = 0
result = n - fn F( fn M( n-1 ) )
end fn = result
 
long i, counter
 
counter = 0
for i = 0 to 19
printf @"%3ld\b", fn F( i )
counter++
if counter mod 5 == 0 then print : counter = 0
next
 
print : print
 
counter = 0
for i = 0 to 19
printf @"%3ld\b", fn M( i )
counter++
if counter mod 5 == 0 then print : counter = 0
next
 
NSLog( @"%@", fn WindowPrintViewString( 1 ) )
 
HandleEvents
</syntaxhighlight>
{{output}}
<pre>
1 1 2 2 3
3 4 5 5 6
6 7 8 8 9
9 10 11 11 12
 
 
0 0 1 2 2
3 4 4 5 6
6 7 7 8 9
9 10 11 11 12
</pre>
 
=={{header|Go}}==
Line 1,929 ⟶ 2,055:
for (i in 0..n) print("%3d".format(i))
println()
println("-".repeat(78(n + 2) * 3))
print("F :")
for (i in 0..24n) print("%3d".format(f(i)))
println()
print("M :")
for (i in 0..24n) print("%3d".format(m(i)))
println()
}</syntaxhighlight>
Line 3,416 ⟶ 3,542:
<pre>F: [1 1 2 2 3 3 4 5 5 6 6 7 8 8 9 9 10 11 11 12]
M: [0 0 1 2 2 3 4 4 5 6 6 7 7 8 9 9 10 11 11 12]</pre>
 
=={{header|REFAL}}==
<syntaxhighlight lang="refal">$ENTRY Go {
= <Prout 'F: ' <S F 0 14>>
<Prout 'M: ' <S M 0 14>>;
};
 
 
F { 0 = 1; s.N = <- s.N <M <F <- s.N 1>>>>; };
M { 0 = 0; s.N = <- s.N <F <M <- s.N 1>>>>; };
 
S {
s.F s.N s.M, <Compare s.N s.M>: '+' = ;
s.F s.N s.M = <Mu s.F s.N> <S s.F <+ s.N 1> s.M>;
};</syntaxhighlight>
{{out}}
<pre>F: 1 1 2 2 3 3 4 5 5 6 6 7 8 8 9
M: 0 0 1 2 2 3 4 4 5 6 6 7 7 8 9</pre>
 
=={{header|REXX}}==
Line 3,783 ⟶ 3,927:
0 0 1 2 2 3 4 4 5 6 6 7 7 8 9 9 10 11 11 12
</pre>
 
=={{header|SETL}}==
<syntaxhighlight lang="setl">program mutual_recursion;
print("F", [f(n) : n in [0..14]]);
print("M", [m(n) : n in [0..14]]);
 
proc f(n);
return {[0,1]}(n) ? n - m(f(n-1));
end proc;
 
proc m(n);
return {[0,0]}(n) ? n - f(m(n-1));
end proc;
end program;</syntaxhighlight>
{{out}}
<pre>F [1 1 2 2 3 3 4 5 5 6 6 7 8 8 9]
M [0 0 1 2 2 3 4 4 5 6 6 7 7 8 9]</pre>
 
=={{header|Sidef}}==
Line 4,263 ⟶ 4,424:
 
=={{header|Wren}}==
<syntaxhighlight lang="ecmascriptwren">var MF = //Fn.new forward{ declaration|n|
 
var F = Fn.new { |n|
if (n == 0) return 1
return n - M.call(F.call(n-1))
}
 
var M = Fn.new { |n|
if (n == 0) return 0
return n - F.call(M.call(n-1))
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