package util // Difference returns the elements in `a` that aren't in `b`. func Difference(a, b []string) []string { mb := make(map[string]struct{}, len(b)) for _, x := range b { mb[x] = struct{}{} } var diff []string for _, x := range a { if _, found := mb[x]; !found { diff = append(diff, x) } } return diff }