syntax - Type int vs. [int ty] in sml

Question

My problem seems simple enough but I can't seem to find an answer anywhere. I'm not sure what the difference is between types int and [int ty] in sml. I'm getting a [tycon mismatch] error when trying to use a list of int tuples as input for my function. For example:

input: number_in_month ((1993, 2, 2), (1776, 7 4), (1994, 7, 5)) 7;

Error: operator and operand don't agree [tycon mistmatch]
operator domain: (int * int * int) list * int
operand:         ([int ty] * [int ty] * [int ty]) *
                 ([int ty] * [int ty] * [int ty]) *
                 ([int ty] * [int ty] * [int ty])

I've tried several ways to enclose my input paren-wise, but nothing seems to change the result.

Answer 1

等待大神解答