-- Lists, tuples, arrays
tc_pat pstate (ListPat pats _) pat_ty thing_inside
= do { (elt_ty, coi) <- boxySplitListTy pat_ty
+ ; let scoi = mkSymCoI coi
; (pats', pats_tvs, res) <- tcMultiple (\p -> tc_lpat p elt_ty)
pats pstate thing_inside
- ; return (mkCoPatCoI coi (ListPat pats' elt_ty) pat_ty, pats_tvs, res) }
+ ; return (mkCoPatCoI scoi (ListPat pats' elt_ty) pat_ty, pats_tvs, res)
+ }
tc_pat pstate (PArrPat pats _) pat_ty thing_inside
= do { (elt_ty, coi) <- boxySplitPArrTy pat_ty
+ ; let scoi = mkSymCoI coi
; (pats', pats_tvs, res) <- tcMultiple (\p -> tc_lpat p elt_ty)
pats pstate thing_inside
; ifM (null pats) (zapToMonotype pat_ty) -- c.f. ExplicitPArr in TcExpr
- ; return (mkCoPatCoI coi (PArrPat pats' elt_ty) pat_ty, pats_tvs, res) }
+ ; return (mkCoPatCoI scoi (PArrPat pats' elt_ty) pat_ty, pats_tvs, res)
+ }
tc_pat pstate (TuplePat pats boxity _) pat_ty thing_inside
= do { let tc = tupleTyCon boxity (length pats)
; (arg_tys, coi) <- boxySplitTyConApp tc pat_ty
+ ; let scoi = mkSymCoI coi
; (pats', pats_tvs, res) <- tcMultiple tc_lpat_pr (pats `zip` arg_tys)
pstate thing_inside
| otherwise = unmangled_result
; ASSERT( length arg_tys == length pats ) -- Syntactically enforced
- return (mkCoPatCoI coi possibly_mangled_result pat_ty, pats_tvs, res)
+ return (mkCoPatCoI scoi possibly_mangled_result pat_ty, pats_tvs, res)
}
------------------------
-> HsConPatDetails Name -> (PatState -> TcM a)
-> TcM (Pat TcId, [TcTyVar], a)
tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
- = do { let (univ_tvs, ex_tvs, eq_spec, eq_theta, dict_theta, arg_tys, _) = dataConFullSig data_con
+ = do { let (univ_tvs, ex_tvs, eq_spec, eq_theta, dict_theta, arg_tys, _)
+ = dataConFullSig data_con
skol_info = PatSkol data_con
origin = SigOrigin skol_info
full_theta = eq_theta ++ dict_theta
-- Instantiate the constructor type variables [a->ty]
- -- This may involve doing a family-instance coercion, and building a wrapper
+ -- This may involve doing a family-instance coercion, and building a
+ -- wrapper
; (ctxt_res_tys, coi) <- boxySplitTyConAppWithFamily tycon pat_ty
- ; let pat_ty' = mkTyConApp tycon ctxt_res_tys
- -- pat_ty /= pat_ty iff coi /= IdCo
- wrap_res_pat res_pat
- = mkCoPatCoI coi (unwrapFamInstScrutinee tycon ctxt_res_tys res_pat) pat_ty
+ ; let sym_coi = mkSymCoI coi -- boxy split coercion oriented wrongly
+ pat_ty' = mkTyConApp tycon ctxt_res_tys
+ -- pat_ty' /= pat_ty iff coi /= IdCo
+
+ wrap_res_pat res_pat = mkCoPatCoI sym_coi uwScrut pat_ty
+ where
+ uwScrut = unwrapFamInstScrutinee tycon ctxt_res_tys res_pat
+
+ ; traceTc $ case sym_coi of
+ IdCo -> text "sym_coi:IdCo"
+ ACo co -> text "sym_coi: ACoI" <+> ppr co
-- Add the stupid theta
; addDataConStupidTheta data_con ctxt_res_tys
then do { -- The common case; no class bindings etc
-- (see Note [Arrows and patterns])
(arg_pats', inner_tvs, res) <- tcConArgs data_con arg_tys'
- arg_pats pstate thing_inside
+ arg_pats pstate thing_inside
; let res_pat = ConPatOut { pat_con = L con_span data_con,
- pat_tvs = [], pat_dicts = [], pat_binds = emptyLHsBinds,
- pat_args = arg_pats', pat_ty = pat_ty' }
+ pat_tvs = [], pat_dicts = [],
+ pat_binds = emptyLHsBinds,
+ pat_args = arg_pats',
+ pat_ty = pat_ty' }
; return (wrap_res_pat res_pat, inner_tvs, res) }
else do -- The general case, with existential, and local equality
-- constraints
{ let eq_preds = [mkEqPred (mkTyVarTy tv, ty) | (tv, ty) <- eq_spec]
- theta' = substTheta tenv (full_theta ++ eq_preds)
+ theta' = substTheta tenv (eq_preds ++ full_theta)
+ -- order is *important* as we generate the list of
+ -- dictionary binders from theta'
ctxt = pat_ctxt pstate
; checkTc (case ctxt of { ProcPat -> False; other -> True })
(existentialProcPat data_con)