56-multisite-structural-join.egi

--
-- Multi-site matcher parameter, joint structural demand (paper Appendix C,
-- Step 3a): site 1's cons pattern makes the committed slot's structural
-- index list-headed; the value-pattern-only site 2 adds no demand but does
-- not erase it.  Supplying `something` at the application then fails the
-- structural half of COERCE-MATCHER-TO-SLOT.
--
-- Expected: Type error at `g something` (bare variable against a list head)
--

def g m :=
  ( matchAll [1, 2] as m with $x :: _ -> x
  , matchAll [1, 2] as m with #[1, 2] -> True )

def t := g something