Multiple Patterns in 1 case

Question

In SML, is it possible for you to have multiple patterns in one case statement?

For example, I have 4 arithmetic operators express in string, \"+\", \"-\", \"*

Answer 1

Expanding upon Ionuț's example, you can even use datatypes with other types in them, but their types (and identifier assignments) must match:

datatype mytype = COST as int | QUANTITY as int | PERSON as string | PET as string;

case item of
  (COST n|QUANTITY n) => print Int.toString n
  |(PERSON name|PET name) => print name

If the types or names don't match, it will get rejected:

case item of
  (COST n|PERSON n) => (* fails because COST is int and PERSON is string *)
  (COST n|QUANTITY q) => (* fails because the identifiers are different *)

And these patterns work in function definitions as well:

fun myfun (COST n|QUANTITY n) = print Int.toString n
   |myfun (PERSON name|PET name) = print name
;