Pattern Values 

Pattern values are defined by placing a pattern in VAL(...) or VAR(...):

VAL(REF("Address") UNAPPLY
  (ID("name"), ID("street"), ID("city"))) := REF("x")
VAR(SOME(ID("y"))) := SOME(LIT(1))

These examples print as:

val Address(name, street, city) = x
var Some(y) = Some(1)