gistfile1.txt

Standard ML of New Jersey v110.76 [built: Fri Oct 11 16:38:25 2013]
- use "hw1.sml";
[opening hw1.sml]
hw1.sml:29.18-30.33 Error: operator and operand don't agree [type mismatch]
  operator domain: {2:'Y; 'Z}
  operand:         date list
  in expression:
    (fn {2=2,...} => 2) d

uncaught exception Error
  raised at: ../compiler/TopLevel/interact/evalloop.sml:66.19-66.27
             ../compiler/TopLevel/interact/evalloop.sml:44.55
             ../compiler/TopLevel/interact/evalloop.sml:296.17-296.20

hw1.sml

(*
 * date is int * int * int
 * where:
 *  first field is a four-digit year
 *  second field is two-digit month [1,12]
 *  third field is two-digit day [1,31]
 *)

type date = int * int * int

fun number_in_month (dates : date list, month : int) : int =
    let
        fun loop (acc : int, d : date list) : int =
            if null d then acc
            else if #2 d = month then loop(acc+1, tl d)
            else loop(acc, tl d)
    in
        loop(0, dates)
    end