jclosure.java

interface Func<B,A> {
  B m(A x);
  }

static <A,B> List<B> map(Func<B,A> f, List<A> xs) {
  if (xs == null) return null;
  return new List<B>(f.m(xs.head),map(f,xs.tail));
  }
  
static List<Integer> doubleAll (List<Integer> xs) {
  return List.map((new Func<Integer,Integer>(){
    public Integer m(Integer x) {
      return x*2;
    }
  }),xs);
}