• simonpj's avatar
    [project @ 2005-03-01 21:40:40 by simonpj] · ff818166
    simonpj authored
    Type signatures and skolem constants (again)
    		Merge to STABLE
    This commit lays to rest the vexed question of skolem constants
    and type signatures.  My fix last week made type-signature variables
    into ordinary meta type variables, because they can be unified
    together (see Note [Signature skolems] in TcType).  But that was wrong
    becuase GADTs will only refine skolems.
    So this commit extends TcTyVarDetails with a new constructors, SigSkolTv,
    which is a skolem (like SkolemTv) but is unifiable (like MetaTv).  It's
    a bit of a hack, but the code came out quite nicely.
    Now the GADT tests work.