wwExpr expr `thenUs` \ new_expr ->
returnUs (mkLets intermediate_bind new_expr)
--- gaw 2004
wwExpr (Case expr binder ty alts)
= wwExpr expr `thenUs` \ new_expr ->
mapUs ww_alt alts `thenUs` \ new_alts ->
--- gaw 2004
returnUs (Case new_expr binder ty new_alts)
where
ww_alt (con, binders, rhs)