update

Task/Combinations/00DESCRIPTION

@@ -12,3 +12,6 @@ For example, <tt>3 comb 5</tt> is
  2 3 4
 
 If it is more "natural" in your language to start counting from <tt>1</tt> instead of <tt>0</tt> the combinations can be of the integers from <tt>1</tt> to <tt>n</tt>.
+
+'''See Also:'''
+{{Template:Combinations and permutations}}

Task/Combinations/ALGOL-68/combinations-1.alg

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*- #
+
+COMMENT REQUIRED BY "prelude_combinations_generative.a68"
+  MODE COMBDATA = ~;
+PROVIDES:
+# COMBDATA*=~* #
+# comb*=~ list* #
+END COMMENT
+
+MODE COMBDATALIST = REF[]COMBDATA;
+MODE COMBDATALISTYIELD = PROC(COMBDATALIST)VOID;
+
+PROC comb gen combinations = (INT m, COMBDATALIST list, COMBDATALISTYIELD yield)VOID:(
+  CASE m IN
+  # case 1: transpose list #
+    FOR i TO UPB list DO yield(list[i]) OD
+  OUT
+    [m + LWB list - 1]COMBDATA out;
+    INT index out := 1;
+    FOR i TO UPB list DO
+      COMBDATA first = list[i];
+    # FOR COMBDATALIST sub recombination IN # comb gen combinations(m - 1, list[i+1:] #) DO (#,
+    ##   (COMBDATALIST sub recombination)VOID:(
+        out[LWB list   ] := first;
+        out[LWB list+1:] := sub recombination;
+        yield(out)
+    # OD #))
+    OD
+  ESAC
+);
+
+SKIP

Task/Combinations/ALGOL-68/combinations-2.alg

@@ -0,0 +1,21 @@
+#!/usr/bin/a68g --script #
+# -*- coding: utf-8 -*- #
+
+CO REQUIRED BY "prelude_combinations.a68" CO
+  MODE COMBDATA = INT;
+#PROVIDES:#
+# COMBDATA~=INT~ #
+# comb ~=int list ~#
+PR READ "prelude_combinations.a68" PR;
+
+FORMAT data fmt = $g(0)$;
+
+main:(
+  INT m = 3;
+  FORMAT list fmt = $"("n(m-1)(f(data fmt)",")f(data fmt)")"$;
+  FLEX[0]COMBDATA test data list := (1,2,3,4,5);
+# FOR COMBDATALIST recombination data IN # comb gen combinations(m, test data list #) DO (#,
+##    (COMBDATALIST recombination)VOID:(
+    printf ((list fmt, recombination, $l$))
+# OD # ))
+)

Task/Combinations/J/combinations-1.j

@@ -1,5 +1,5 @@
 comb1=: dyad define
   c=. 1 {.~ - d=. 1+y-x
   z=. i.1 0
-  for_j. (d-1+y)+/&i.d do. z=. (c#j) ,. z{~;(-c){.&.><i.{.c=. +/\.c end.
+  for_j. (d-1+y)+/&i.d do. z=. (c#j) ,. z{~;(-c){.&.><i.{.c=. +/\.c end.
 )

Task/Combinations/J/combinations-3.j

@@ -0,0 +1 @@
+combb=: (#~ ((-:/:~)>/:~-:\:~)"1)@(# #: [: i. ^~)

Task/Combinations/Julia/combinations.julia

@@ -1,13 +1,3 @@
-julia> for i in @task combinations(1:5,3)
+for i in @task combinations(1:5,3)
 println(i)
 end
-[1, 2, 3]
-[1, 2, 4]
-[1, 3, 4]
-[2, 3, 4]
-[1, 2, 5]
-[1, 3, 5]
-[2, 3, 5]
-[1, 4, 5]
-[2, 4, 5]
-[3, 4, 5]

Task/Combinations/Perl-6/combinations.pl6

@@ -3,9 +3,10 @@ proto combine (Int, @) {*}
 multi combine (0,  @)  { [] }
 multi combine ($,  []) { () }
 multi combine ($n, [$head, *@tail]) {
-    map( { [$head, @^others] },
-            combine($n-1, @tail) ),
-    combine($n, @tail);
+    gather {
+	take [$head, @$_] for combine($n-1, @tail);
+	take [ @$_ ]      for combine($n  , @tail);
+    }
 }
 
-.say for combine(3, [^5]);
+say  combine(3, [^5]).perl;

Task/Combinations/Racket/combinations.rkt

@@ -0,0 +1,9 @@
+(define sublists
+  (match-lambda**
+   [(0 _)           '(())]
+   [(_ '())         '()]
+   [(m (cons x xs)) (append (map (curry cons x) (sublists (- m 1) xs))
+                            (sublists m xs))]))
+
+(define (combinations n m)
+  (sublists n (range m)))