[project @ 2005-03-01 21:40:40 by simonpj]
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.