Pattern Matching

(Syntax unsettled)

The match keyword followed by {, a number of clauses and finally a }. Each clause is a destructuring, an = then an expression.

mapMaybe = f. match {
  Some a = Some $ f a
  None = None
}

It evaluates to a function, so the mapMaybe above infers as:

mapMaybe: forall a b f: (a -> b). f -> (Some a + None) -> (Some b + None)

This currying, data-last friendly syntax subsumes:

Declaration pattern matching
if expressions
case _ of
\case