X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcPat.lhs;h=9c6a0dc11bc231c582bb7133ae911248f939d0dc;hp=a8e2d39f7573ba1b421eaf99c23e40baaef97b66;hb=17b297d97d327620ed6bfab942f8992b2446f1bf;hpb=e2b5796d58ffce3f62f71439df51932679ffb16c diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs index a8e2d39..9c6a0dc 100644 --- a/compiler/typecheck/TcPat.lhs +++ b/compiler/typecheck/TcPat.lhs @@ -6,6 +6,13 @@ TcPat: Typechecking patterns \begin{code} +{-# OPTIONS_GHC -w #-} +-- The above warning supression flag is a temporary kludge. +-- While working on this module you are encouraged to remove it and fix +-- any warnings in the module. See +-- http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings +-- for details + module TcPat ( tcLetPat, tcLamPat, tcLamPats, tcOverloadedLit, addDataConStupidTheta, badFieldCon, polyPatSig ) where @@ -31,6 +38,7 @@ import TcHsType import TysWiredIn import TcGadt import Type +import Coercion import StaticFlags import TyCon import DataCon @@ -59,7 +67,8 @@ tcLetPat :: (Name -> Maybe TcRhoType) -> TcM (LPat TcId, a) tcLetPat sig_fn pat pat_ty thing_inside = do { let init_state = PS { pat_ctxt = LetPat sig_fn, - pat_reft = emptyRefinement } + pat_reft = emptyRefinement, + pat_eqs = False } ; (pat', ex_tvs, res) <- tc_lpat pat pat_ty init_state (\ _ -> thing_inside) -- Don't know how to deal with pattern-bound existentials yet @@ -104,11 +113,13 @@ tc_lam_pats :: [(LPat Name,BoxySigmaType)] -> ((Refinement,BoxyRhoType) -> TcM a) -- Checker for body, given its result type -> TcM ([LPat TcId], a) tc_lam_pats pat_ty_prs (reft, res_ty) thing_inside - = do { let init_state = PS { pat_ctxt = LamPat, pat_reft = reft } + = do { let init_state = PS { pat_ctxt = LamPat, pat_reft = reft, pat_eqs = False } ; (pats', ex_tvs, res) <- tcMultiple tc_lpat_pr pat_ty_prs init_state $ \ pstate' -> - refineEnvironment (pat_reft pstate') $ - thing_inside (pat_reft pstate', res_ty) + refineEnvironment (pat_reft pstate') (pat_eqs pstate') $ + if (pat_eqs pstate' && (not $ isRigidTy res_ty)) + then failWithTc (nonRigidResult res_ty) + else thing_inside (pat_reft pstate', res_ty) ; let tys = map snd pat_ty_prs ; tcCheckExistentialPat pats' ex_tvs tys res_ty @@ -138,7 +149,9 @@ tcCheckExistentialPat pats ex_tvs pat_tys body_ty data PatState = PS { pat_ctxt :: PatCtxt, - pat_reft :: Refinement -- Binds rigid TcTyVars to their refinements + pat_reft :: Refinement, -- Binds rigid TcTyVars to their refinements + pat_eqs :: Bool -- <=> there are GADT equational constraints + -- for refinement } data PatCtxt @@ -434,9 +447,15 @@ tc_pat pstate pat_in@(ConPatIn (L con_span con_name) arg_pats) pat_ty thing_insi ------------------------ -- Literal patterns tc_pat pstate (LitPat simple_lit) pat_ty thing_inside - = do { boxyUnify (hsLitType simple_lit) pat_ty + = do { let lit_ty = hsLitType simple_lit + ; coi <- boxyUnify lit_ty pat_ty + -- coi is of kind: lit_ty ~ pat_ty ; res <- thing_inside pstate - ; returnM (LitPat simple_lit, [], res) } + ; span <- getSrcSpanM + -- pattern coercions have to + -- be of kind: pat_ty ~ lit_ty + -- hence, sym coi + ; returnM (wrapPatCoI (mkSymCoI coi) (LitPat simple_lit) pat_ty, [], res) } ------------------------ -- Overloaded patterns: n, and n+k @@ -547,7 +566,7 @@ tcConPat :: PatState -> SrcSpan -> DataCon -> TyCon -> 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, 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 @@ -558,12 +577,12 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside ; let tenv = zipTopTvSubst (univ_tvs ++ ex_tvs) (ctxt_res_tys ++ mkTyVarTys ex_tvs') eq_spec' = substEqSpec tenv eq_spec - theta' = substTheta tenv theta + theta' = substTheta tenv (eq_theta ++ dict_theta) arg_tys' = substTys tenv arg_tys ; co_vars <- newCoVars eq_spec' -- Make coercion variables ; pstate' <- refineAlt data_con pstate ex_tvs' co_vars pat_ty - + ; ((arg_pats', inner_tvs, res), lie_req) <- getLIE $ tcConArgs data_con arg_tys' arg_pats pstate' thing_inside @@ -725,6 +744,7 @@ refineAlt :: DataCon -- For tracing only -> TcM PatState refineAlt con pstate ex_tvs [] pat_ty + | null $ dataConEqTheta con = return pstate -- Common case: no equational constraints refineAlt con pstate ex_tvs co_vars pat_ty @@ -751,7 +771,7 @@ refineAlt con pstate ex_tvs co_vars pat_ty ; case gadtRefine (pat_reft pstate) ex_tvs co_vars of { Failed msg -> failWithTc (inaccessibleAlt msg) ; Succeeded reft -> do { traceTc trace_msg - ; return (pstate { pat_reft = reft }) } + ; return (pstate { pat_reft = reft, pat_eqs = (pat_eqs pstate || not (null $ dataConEqTheta con)) }) } -- DO NOT refine the envt right away, because we -- might be inside a lazy pattern. Instead, refine pstate where @@ -920,7 +940,7 @@ patCtxt pat = Just (hang (ptext SLIT("In the pattern:")) existentialExplode pat = hang (vcat [text "My brain just exploded.", text "I can't handle pattern bindings for existentially-quantified constructors.", - text "Instead, use a case-expression to unpack the constructor.", + text "Instead, use a case-expression, or do-notation, to unpack the constructor.", text "In the binding group for"]) 4 (ppr pat) @@ -965,6 +985,16 @@ nonRigidMatch con = hang (ptext SLIT("GADT pattern match in non-rigid context for") <+> quotes (ppr con)) 2 (ptext SLIT("Tell GHC HQ if you'd like this to unify the context")) +nonRigidResult res_ty + = hang (ptext SLIT("GADT pattern match with non-rigid result type") <+> quotes (ppr res_ty)) + 2 (ptext SLIT("Tell GHC HQ if you'd like this to unify the context")) + inaccessibleAlt msg = hang (ptext SLIT("Inaccessible case alternative:")) 2 msg \end{code} + +\begin{code} +wrapPatCoI :: CoercionI -> Pat a -> TcType -> Pat a +wrapPatCoI IdCo pat ty = pat +wrapPatCoI (ACo co) pat ty = CoPat (WpCo co) pat ty +\end{code}