combinations

combinations.d

import std.stdio;
import std.algorithm;

void combinations(T)(T[] array) {
        comb(array, []);
}

private void comb(T)(T[] array, T[] prefix) {
        if (array.length) {
                writeln(prefix ~ [array[0]]);
                comb(array[1..$], prefix ~ [array[0]]);
                comb(array[1..$], prefix);
        }
}

void main() {
        combinations([1,2,3,4]);
}