Go string-permutation generator (not ideal since it doesn't nicely handle the channel and goroutine)

perm.go

func PermutationGenerator(in string) chan string {
	r := make(chan string, 0)
	var perm func([]rune, int)
	perm = func(a []rune, i int) {
		if i > len(a) {
			r <- string(a)
			return
		}
		perm(a, i+1)
		for j := i + 1; j < len(a); j++ {
			a[i], a[j] = a[j], a[i]
			perm(a, i+1)
			a[i], a[j] = a[j], a[i]
		}
		if i == 0 {
			close(r)
		}
	}
	go perm([]rune(in), 0)
	return r
}