Time for an 2014 update…

Task/Permutations/D/permutations-2.d

@@ -6,7 +6,7 @@ struct Permutations(bool doCopy=true, T) if (isMutable!T) {
     private uint[31] indexes;
     private ulong tot;
 
-    this (/*in*/ T[] items) /*pure nothrow*/
+    this (in T[] items) pure /*nothrow*/
     in {
         static enum string L = text(indexes.length); // impure
         assert(items.length >= 0 && items.length <= indexes.length,
@@ -66,21 +66,18 @@ struct Permutations(bool doCopy=true, T) if (isMutable!T) {
 }
 
 Permutations!(doCopy,T) permutations(bool doCopy=true, T)
-                                    (/*in*/ T[] items)
-/*pure nothrow*/ if (isMutable!T) {
+                                    (in T[] items)
+pure /*nothrow*/ if (isMutable!T) {
     return Permutations!(doCopy, T)(items);
-} unittest {
-    import std.bigint;
-    foreach (p; permutations([BigInt(1), BigInt(2), BigInt(3)]))
-        assert((p[0] + 1) > 0);
 }
 
 version (permutations2_main) {
     void main() {
         import std.stdio, std.bigint;
-        foreach (p; permutations!false([1, 2, 3]))
-            writeln(p);
-        alias BigInt B;
-        foreach (p; permutations!false([B(1), B(2), B(3)])) {}
+        alias B = BigInt;
+        foreach (p; [B(1), B(2), B(3)].permutations)
+            assert((p[0] + 1) > 0);
+        [1, 2, 3].permutations!false.writeln;
+        [B(1), B(2), B(3)].permutations!false.writeln;
     }
 }

Task/Permutations/Liberty-BASIC/permutations-1.liberty

@@ -0,0 +1,28 @@
+n=3
+dim a(n+1)  '+1 needed due to bug in LB that checks loop condition
+    '   until (i=0) or (a(i)<a(i+1))
+    'before executing i=i-1 in loop body.
+for i=1 to n: a(i)=i: next
+do
+  for i=1 to n: print a(i);: next: print
+  i=n
+  do
+    i=i-1
+  loop until (i=0) or (a(i)<a(i+1))
+  j=i+1
+  k=n
+  while j<k
+    'swap a(j),a(k)
+    tmp=a(j): a(j)=a(k): a(k)=tmp
+    j=j+1
+    k=k-1
+  wend
+  if i>0 then
+    j=i+1
+    while a(j)<a(i)
+      j=j+1
+    wend
+    'swap a(i),a(j)
+    tmp=a(j): a(j)=a(i): a(i)=tmp
+  end if
+loop until i=0

Task/Permutations/Liberty-BASIC/permutations-2.liberty

@@ -0,0 +1,19 @@
+n = 3
+
+s$=""
+for i = 1 to n
+    s$=s$;i
+next
+
+res$=permutation$("", s$)
+
+Function permutation$(pre$, post$)
+    lgth = Len(post$)
+    If lgth < 2 Then
+        print pre$;post$
+    Else
+        For i = 1 To lgth
+            tmp$=permutation$(pre$+Mid$(post$,i,1),Left$(post$,i-1)+Right$(post$,lgth-i))
+        Next i
+    End If
+End Function