Improve a parser error message.
checkDictTy (HsTyVar t) args@(_:_) | not (isRdrTyVar t)
= returnP (mkHsDictTy t args)
checkDictTy (HsAppTy l r) args = checkDictTy l (r:args)
checkDictTy (HsTyVar t) args@(_:_) | not (isRdrTyVar t)
= returnP (mkHsDictTy t args)
checkDictTy (HsAppTy l r) args = checkDictTy l (r:args)
-checkDictTy _ _ = parseError "Illegal class assertion"
+checkDictTy _ _ = parseError "Malformed context in instance header"
-- Put more comments!
-- Checks that the lhs of a datatype declaration
-- Put more comments!
-- Checks that the lhs of a datatype declaration