Permutations: Difference between revisions

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 =={{header|D}}==
-===Eager version===
+===Simple Eager version===
+Compile with -version=permutations1_main to see the output.
-<lang d>import std.stdio: writeln;
+<lang d>T[][] permutations(T)(T[] items) pure nothrow {
-T[][] permutations(T)(T[] items) {
     T[][] result;
-    void perms(T[] s, T[] prefix=[]) {
+    void perms(T[] s, T[] prefix=[]) nothrow {
         if (s.length)
-            foreach (i, c; s)
+            foreach (immutable i, immutable c; s)
                perms(s[0 .. i] ~ s[i+1 .. $], prefix ~ c);
         else
@@ Line 916: / Line 915: @@
 }
+version (permutations1_main) {
-void main() {
+    void main() {
-    foreach (p; permutations([1, 2, 3]))
-        writeln(p);
+        import std.stdio;
+        writefln("%(%s\n%)", [1, 2, 3].permutations);
+    }
 }</lang>
 {{out}}
@@ Line 927: / Line 928: @@
 [3, 1, 2]
 [3, 2, 1]</pre>
 ===Fast Lazy Version===
 Compiled with <code>-version=permutations2_main</code> produces the same output: