-- means that we can avoid tests in exprIsConApp, for example.
-- This is important: if exprIsConApp says 'yes' for a recursive
-- thing, then we can get into an infinite loop
-
-- If the unfolding is a value, the demand info may
-- go pear-shaped, so we nuke it. Example:
-- let x = (a,b) in
simplDefault env case_bndr' imposs_cons cont Nothing
= return [] -- No default branch
+
simplDefault env case_bndr' imposs_cons cont (Just rhs)
| -- This branch handles the case where we are
-- scrutinisng an algebraic data type
two_or_more -> simplify_default (map DataAlt gadt_imposs ++ imposs_cons)
- | otherwise
+ | otherwise
= simplify_default imposs_cons
where
cant_match tys data_con = not (dataConCanMatch data_con tys)