Generics

fn mapInt(list: IntList, fun: (Int) -> Int) -> IntList {
  // ...
}

fn mapFloat(list: FloatList, fun: (Float) -> Float) -> FloatList {
  // ...
}

fn map<T>(list: List<T>, fun: (T) -> T) -> List<T> {
  // ...
}

map<Int, Int>([1, 2, 3], increment)

fn map<T, U>(list: List<T>, fun: (T) -> U) -> List<U> {
  // ...
}

map<Int, Int>([1, 2, 3], increment) //=> [2, 3, 4] : List<Int>
map<Int, Bool>([1, 2, 3], (>)(2)) //=> [False, False, True] : List<Bool>