-- I don't think I have to refine the set of global type variables in scope
-- Reason: the refinement never increases that set
refineEnvironment reft thing_inside
+ | isEmptyRefinement reft -- Common case
+ = thing_inside
+ | otherwise
= do { env <- getLclEnv
; let le' = mapNameEnv refine (tcl_env env)
; setLclEnv (env {tcl_env = le'}) thing_inside }
where
refine elt@(ATcId { tct_co = Just co, tct_type = ty })
- = let (co', ty') = refineType reft ty
- in elt { tct_co = Just (co' <.> co), tct_type = ty' }
- refine (ATyVar tv ty) = ATyVar tv (snd (refineType reft ty))
- -- Ignore the coercion that refineType returns
- refine elt = elt
+ | Just (co', ty') <- refineType reft ty
+ = elt { tct_co = Just (WpCo co' <.> co), tct_type = ty' }
+ refine (ATyVar tv ty)
+ | Just (_, ty') <- refineType reft ty
+ = ATyVar tv ty' -- Ignore the coercion that refineType returns
+
+ refine elt = elt -- Common case
\end{code}
%************************************************************************