ML

ML is a family of general-purpose, strong-typed, non-pure functional languages. The most known derivatives of ML are Standard ML and OCaml.

Features:

• Supporting both of functional and imperative coding styles
• Object oriented programming (OCaml)
• Garbage collection
• Polymorphic types
• Pattern matching
• Highly expressive syntax

Standard ML implementations:

• MLton
• Moscow ML
• Poly/ML
• SML/NJ - Standard ML of New Jersey

OCaml:

• OCaml home - Distributions and documentation

Example code (in OCaml):

(* An implementation of the factorial computing function
 * in different coding styles.
 * Note that the argument shall be >= 0
 **)

(* Functional style *)
let rec fact_1 n =
  match n with
    0 -> 1
  | n -> n * fact_1 (n - 1)
;;

(* Imperative style *)
let rec fact_2 n =
  if n = 0 then 1
  else n * fact_2 (n - 1)
;;

(* Imperative style without the recursion *)
let fact_3 n =
  let result = ref 1 in
  if n > 0 then
    for i = 1 to n do result := !result * i done
  else result := 0;
  !result
;;