\begin{code}
optCoercion :: Coercion -> Coercion
-optCoercion co = co
-{-
- = pprTrace "optCoercion" (ppr co $$ ppr (coercionKind co)) $
- ASSERT2( coercionKind co `eq` coercionKind result, ppr co $$ ppr result )
+optCoercion co
+ = ASSERT2( coercionKind co `eq` coercionKind result,
+ ppr co $$ ppr result $$ ppr (coercionKind co) $$ ppr (coercionKind result) )
result
where
(s1,t1) `eq` (s2,t2) = s1 `coreEqType` s2 && t1 `coreEqType` t2
else if chan1 || chan2
then (TyConApp tc [ty1',ty2'], True , False)
else (ty , False, False)
- | otherwise
+ | tc == leftCoercionTyCon, [ty1] <- args
+ = let (ty1', chan1, id1) = go ty1
+ in if chan1
+ then (TyConApp tc [ty1'], True , id1)
+ else (ty , False, id1)
+ | tc == rightCoercionTyCon, [ty1] <- args
+ = let (ty1', chan1, id1) = go ty1
+ in if chan1
+ then (TyConApp tc [ty1'], True , id1)
+ else (ty , False, id1)
+ | not (isCoercionTyCon tc)
= let (args', chans, ids) = mapAndUnzip3 go args
in if or chans
then (TyConApp tc args', True , and ids)
- else (ty , False, and ids)
+ else (ty , False, and ids)
+ | otherwise
+ = (ty, False, False)
go ty@(FunTy ty1 ty2)
= let (ty1',chan1,id1) = go ty1
(ty2',chan2,id2) = go ty2
in if chan1
then (PredTy (IParam name ty1'), True , id1)
else (ty , False, id1)
--}
\end{code}