Bubble Sort

bubble_sort.sml

(** Bubble Sort **)
fun bubble_sort nil      = nil
  | bubble_sort (x::xs)  = 
    let
      fun sort_aux nil           = nil
        | sort_aux (x::nil)      = x::nil
        | sort_aux (x::(y::nil)) = if x < y then x::(y::nil)           else y::(x::nil)
        | sort_aux (x::(y::xs))  = if x < y then x::(sort_aux (y::xs)) else y::(sort_aux (x::xs))
	  
      fun sort_ _ nil     = nil
        | sort_ 0 (x::xs) = sort_aux (x::xs)
        | sort_ n (x::xs) = sort_ (n-1) (sort_aux (x::xs))
    in
      sort_ (length (x::xs)) (x::xs)
    end;

bubble_sort [5, 1, 2, 4, 1, 3];
(* val it = [1,1,2,3,4,5] : int list *)