module TcPat ( tcLetPat
, TcPragEnv, lookupPragEnv, emptyPragEnv
, LetBndrSpec(..), addInlinePrags
, tcPat, tcPat_O, tcPats, newNoSigLetBndr
, addDataConStupidTheta, badFieldCon, polyPatSig ) where
#include "HsVersions.h"
import TcExpr( tcSyntaxOp, tcSyntaxOpGen, tcInferSigma )
import HsSyn
import TcHsSyn
import TcRnMonad
import Inst
import Id
import Var
import Name
import NameEnv
import RdrName
import TcEnv
import TcMType
import TcValidity( arityErr )
import TcType
import TcUnify
import TcHsType
import TysWiredIn
import TcEvidence
import TyCon
import DataCon
import PatSyn
import ConLike
import PrelNames
import BasicTypes hiding (SuccessFlag(..))
import DynFlags
import SrcLoc
import VarSet
import Util
import Outputable
import Maybes( orElse )
import qualified GHC.LanguageExtensions as LangExt
import Control.Monad
import Control.Arrow ( second )
tcLetPat :: TcSigFun -> LetBndrSpec
-> LPat Name -> ExpSigmaType
-> TcM a
-> TcM (LPat TcId, a)
tcLetPat sig_fn no_gen pat pat_ty thing_inside
= tc_lpat pat pat_ty penv thing_inside
where
penv = PE { pe_lazy = True
, pe_ctxt = LetPat sig_fn no_gen
, pe_orig = PatOrigin }
tcPats :: HsMatchContext Name
-> [LPat Name]
-> [ExpSigmaType]
-> TcM a
-> TcM ([LPat TcId], a)
tcPats ctxt pats pat_tys thing_inside
= tc_lpats penv pats pat_tys thing_inside
where
penv = PE { pe_lazy = False, pe_ctxt = LamPat ctxt, pe_orig = PatOrigin }
tcPat :: HsMatchContext Name
-> LPat Name -> ExpSigmaType
-> TcM a
-> TcM (LPat TcId, a)
tcPat ctxt = tcPat_O ctxt PatOrigin
tcPat_O :: HsMatchContext Name
-> CtOrigin
-> LPat Name -> ExpSigmaType
-> TcM a
-> TcM (LPat TcId, a)
tcPat_O ctxt orig pat pat_ty thing_inside
= tc_lpat pat pat_ty penv thing_inside
where
penv = PE { pe_lazy = False, pe_ctxt = LamPat ctxt, pe_orig = orig }
data PatEnv
= PE { pe_lazy :: Bool
, pe_ctxt :: PatCtxt
, pe_orig :: CtOrigin
}
data PatCtxt
= LamPat
(HsMatchContext Name)
| LetPat
TcSigFun
LetBndrSpec
data LetBndrSpec
= LetLclBndr
| LetGblBndr TcPragEnv
makeLazy :: PatEnv -> PatEnv
makeLazy penv = penv { pe_lazy = True }
inPatBind :: PatEnv -> Bool
inPatBind (PE { pe_ctxt = LetPat {} }) = True
inPatBind (PE { pe_ctxt = LamPat {} }) = False
type TcPragEnv = NameEnv [LSig Name]
emptyPragEnv :: TcPragEnv
emptyPragEnv = emptyNameEnv
lookupPragEnv :: TcPragEnv -> Name -> [LSig Name]
lookupPragEnv prag_fn n = lookupNameEnv prag_fn n `orElse` []
tcPatBndr :: PatEnv -> Name -> ExpSigmaType -> TcM (TcCoercionN, TcId)
tcPatBndr (PE { pe_ctxt = LetPat lookup_sig no_gen}) bndr_name pat_ty
| LetGblBndr prags <- no_gen
, Just (TcIdSig sig) <- lookup_sig bndr_name
, Just poly_id <- completeIdSigPolyId_maybe sig
= do { bndr_id <- addInlinePrags poly_id (lookupPragEnv prags bndr_name)
; traceTc "tcPatBndr(gbl,sig)" (ppr bndr_id $$ ppr (idType bndr_id))
; co <- unifyPatType bndr_id (idType bndr_id) pat_ty
; return (co, bndr_id) }
| otherwise
= do { pat_ty <- expTypeToType pat_ty
; bndr_id <- newNoSigLetBndr no_gen bndr_name pat_ty
; traceTc "tcPatBndr(no-sig)" (ppr bndr_id $$ ppr (idType bndr_id))
; return (mkTcNomReflCo pat_ty, bndr_id) }
tcPatBndr (PE { pe_ctxt = _lam_or_proc }) bndr_name pat_ty
= do { pat_ty <- expTypeToType pat_ty
; return (mkTcNomReflCo pat_ty, mkLocalId bndr_name pat_ty) }
newNoSigLetBndr :: LetBndrSpec -> Name -> TcType -> TcM TcId
newNoSigLetBndr LetLclBndr name ty
=do { mono_name <- newLocalName name
; return (mkLocalId mono_name ty) }
newNoSigLetBndr (LetGblBndr prags) name ty
= addInlinePrags (mkLocalId name ty) (lookupPragEnv prags name)
addInlinePrags :: TcId -> [LSig Name] -> TcM TcId
addInlinePrags poly_id prags
| inl@(L _ prag) : inls <- inl_prags
= do { traceTc "addInlinePrag" (ppr poly_id $$ ppr prag)
; unless (null inls) (warn_multiple_inlines inl inls)
; return (poly_id `setInlinePragma` prag) }
| otherwise
= return poly_id
where
inl_prags = [L loc prag | L loc (InlineSig _ prag) <- prags]
warn_multiple_inlines _ [] = return ()
warn_multiple_inlines inl1@(L loc prag1) (inl2@(L _ prag2) : inls)
| inlinePragmaActivation prag1 == inlinePragmaActivation prag2
, isEmptyInlineSpec (inlinePragmaSpec prag1)
=
warn_multiple_inlines inl2 inls
| otherwise
= setSrcSpan loc $
addWarnTc NoReason
(hang (text "Multiple INLINE pragmas for" <+> ppr poly_id)
2 (vcat (text "Ignoring all but the first"
: map pp_inl (inl1:inl2:inls))))
pp_inl (L loc prag) = ppr prag <+> parens (ppr loc)
type Checker inp out = forall r.
inp
-> PatEnv
-> TcM r
-> TcM (out, r)
tcMultiple :: Checker inp out -> Checker [inp] [out]
tcMultiple tc_pat args penv thing_inside
= do { err_ctxt <- getErrCtxt
; let loop _ []
= do { res <- thing_inside
; return ([], res) }
loop penv (arg:args)
= do { (p', (ps', res))
<- tc_pat arg penv $
setErrCtxt err_ctxt $
loop penv args
; return (p':ps', res) }
; loop penv args }
tc_lpat :: LPat Name
-> ExpSigmaType
-> PatEnv
-> TcM a
-> TcM (LPat TcId, a)
tc_lpat (L span pat) pat_ty penv thing_inside
= setSrcSpan span $
do { (pat', res) <- maybeWrapPatCtxt pat (tc_pat penv pat pat_ty)
thing_inside
; return (L span pat', res) }
tc_lpats :: PatEnv
-> [LPat Name] -> [ExpSigmaType]
-> TcM a
-> TcM ([LPat TcId], a)
tc_lpats penv pats tys thing_inside
= ASSERT2( equalLength pats tys, ppr pats $$ ppr tys )
tcMultiple (\(p,t) -> tc_lpat p t)
(zipEqual "tc_lpats" pats tys)
penv thing_inside
tc_pat :: PatEnv
-> Pat Name
-> ExpSigmaType
-> TcM a
-> TcM (Pat TcId,
a)
tc_pat penv (VarPat (L l name)) pat_ty thing_inside
= do { (co, id) <- tcPatBndr penv name pat_ty
; res <- tcExtendIdEnv1 name id thing_inside
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPatCo co (VarPat (L l id)) pat_ty, res) }
tc_pat penv (ParPat pat) pat_ty thing_inside
= do { (pat', res) <- tc_lpat pat pat_ty penv thing_inside
; return (ParPat pat', res) }
tc_pat penv (BangPat pat) pat_ty thing_inside
= do { (pat', res) <- tc_lpat pat pat_ty penv thing_inside
; return (BangPat pat', res) }
tc_pat penv lpat@(LazyPat pat) pat_ty thing_inside
= do { (pat', (res, pat_ct))
<- tc_lpat pat pat_ty (makeLazy penv) $
captureConstraints thing_inside
; emitConstraints pat_ct
; when (any (isUnliftedType . idType) $ collectPatBinders pat') $
lazyUnliftedPatErr lpat
; pat_ty <- readExpType pat_ty
; _ <- unifyType noThing (typeKind pat_ty) liftedTypeKind
; return (LazyPat pat', res) }
tc_pat _ (WildPat _) pat_ty thing_inside
= do { res <- thing_inside
; pat_ty <- expTypeToType pat_ty
; return (WildPat pat_ty, res) }
tc_pat penv (AsPat (L nm_loc name) pat) pat_ty thing_inside
= do { (co, bndr_id) <- setSrcSpan nm_loc (tcPatBndr penv name pat_ty)
; (pat', res) <- tcExtendIdEnv1 name bndr_id $
tc_lpat pat (mkCheckExpType $ idType bndr_id)
penv thing_inside
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPatCo co (AsPat (L nm_loc bndr_id) pat') pat_ty, res) }
tc_pat penv (ViewPat expr pat _) overall_pat_ty thing_inside
= do {
; (expr',expr'_inferred) <- tcInferSigma expr
; let expr_orig = exprCtOrigin (unLoc expr)
herald = text "A view pattern expression expects"
; (expr_wrap1, [inf_arg_ty], inf_res_ty)
<- matchActualFunTys herald expr_orig (Just expr) 1 expr'_inferred
; let pat_origin = GivenOrigin (SigSkol GenSigCtxt overall_pat_ty)
; expr_wrap2 <- tcSubTypeET pat_origin overall_pat_ty inf_arg_ty
; (pat', res) <- tc_lpat pat (mkCheckExpType inf_res_ty) penv thing_inside
; overall_pat_ty <- readExpType overall_pat_ty
; let expr_wrap2' = mkWpFun expr_wrap2 idHsWrapper
overall_pat_ty inf_res_ty
expr_wrap = expr_wrap2' <.> expr_wrap1
; return (ViewPat (mkLHsWrap expr_wrap expr') pat' overall_pat_ty, res) }
tc_pat penv (SigPatIn pat sig_ty) pat_ty thing_inside
= do { (inner_ty, tv_binds, wcs, wrap) <- tcPatSig (inPatBind penv)
sig_ty pat_ty
; (pat', res) <- tcExtendTyVarEnv2 wcs $
tcExtendTyVarEnv tv_binds $
tc_lpat pat (mkCheckExpType inner_ty) penv thing_inside
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPat wrap (SigPatOut pat' inner_ty) pat_ty, res) }
tc_pat penv (ListPat pats _ Nothing) pat_ty thing_inside
= do { (coi, elt_ty) <- matchExpectedPatTy matchExpectedListTy penv pat_ty
; (pats', res) <- tcMultiple (\p -> tc_lpat p (mkCheckExpType elt_ty))
pats penv thing_inside
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPat coi (ListPat pats' elt_ty Nothing) pat_ty, res)
}
tc_pat penv (ListPat pats _ (Just (_,e))) pat_ty thing_inside
= do { tau_pat_ty <- expTypeToType pat_ty
; ((pats', res, elt_ty), e')
<- tcSyntaxOpGen ListOrigin e [SynType (mkCheckExpType tau_pat_ty)]
SynList $
\ [elt_ty] ->
do { (pats', res) <- tcMultiple (\p -> tc_lpat p (mkCheckExpType elt_ty))
pats penv thing_inside
; return (pats', res, elt_ty) }
; return (ListPat pats' elt_ty (Just (tau_pat_ty,e')), res)
}
tc_pat penv (PArrPat pats _) pat_ty thing_inside
= do { (coi, elt_ty) <- matchExpectedPatTy matchExpectedPArrTy penv pat_ty
; (pats', res) <- tcMultiple (\p -> tc_lpat p (mkCheckExpType elt_ty))
pats penv thing_inside
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPat coi (PArrPat pats' elt_ty) pat_ty, res)
}
tc_pat penv (TuplePat pats boxity _) pat_ty thing_inside
= do { let arity = length pats
tc = tupleTyCon boxity arity
; (coi, arg_tys) <- matchExpectedPatTy (matchExpectedTyConApp tc)
penv pat_ty
; let con_arg_tys = case boxity of Unboxed -> drop arity arg_tys
Boxed -> arg_tys
; (pats', res) <- tc_lpats penv pats (map mkCheckExpType con_arg_tys)
thing_inside
; dflags <- getDynFlags
; let
unmangled_result = TuplePat pats' boxity con_arg_tys
possibly_mangled_result
| gopt Opt_IrrefutableTuples dflags &&
isBoxed boxity = LazyPat (noLoc unmangled_result)
| otherwise = unmangled_result
; pat_ty <- readExpType pat_ty
; ASSERT( length con_arg_tys == length pats )
return (mkHsWrapPat coi possibly_mangled_result pat_ty, res)
}
tc_pat penv (ConPatIn con arg_pats) pat_ty thing_inside
= tcConPat penv con pat_ty arg_pats thing_inside
tc_pat _ (LitPat simple_lit) pat_ty thing_inside
= do { let lit_ty = hsLitType simple_lit
; co <- unifyPatType simple_lit lit_ty pat_ty
; res <- thing_inside
; pat_ty <- readExpType pat_ty
; return ( mkHsWrapPatCo co (LitPat simple_lit) pat_ty
, res) }
tc_pat _ (NPat (L l over_lit) mb_neg eq _) pat_ty thing_inside
= do { let orig = LiteralOrigin over_lit
; ((lit', mb_neg'), eq')
<- tcSyntaxOp orig eq [SynType pat_ty, SynAny]
(mkCheckExpType boolTy) $
\ [neg_lit_ty] ->
let new_over_lit lit_ty = newOverloadedLit over_lit
(mkCheckExpType lit_ty)
in case mb_neg of
Nothing -> (, Nothing) <$> new_over_lit neg_lit_ty
Just neg ->
second Just <$>
(tcSyntaxOp orig neg [SynRho] (mkCheckExpType neg_lit_ty) $
\ [lit_ty] -> new_over_lit lit_ty)
; res <- thing_inside
; pat_ty <- readExpType pat_ty
; return (NPat (L l lit') mb_neg' eq' pat_ty, res) }
tc_pat penv (NPlusKPat (L nm_loc name) (L loc lit) _ ge minus _) pat_ty thing_inside
= do { pat_ty <- expTypeToType pat_ty
; let orig = LiteralOrigin lit
; (lit1', ge')
<- tcSyntaxOp orig ge [synKnownType pat_ty, SynRho]
(mkCheckExpType boolTy) $
\ [lit1_ty] ->
newOverloadedLit lit (mkCheckExpType lit1_ty)
; ((lit2', minus_wrap, bndr_id), minus')
<- tcSyntaxOpGen orig minus [synKnownType pat_ty, SynRho] SynAny $
\ [lit2_ty, var_ty] ->
do { lit2' <- newOverloadedLit lit (mkCheckExpType lit2_ty)
; (co, bndr_id) <- setSrcSpan nm_loc $
tcPatBndr penv name (mkCheckExpType var_ty)
; return (lit2', mkWpCastN co, bndr_id) }
; unlessM (xoptM LangExt.RebindableSyntax) $
do { icls <- tcLookupClass integralClassName
; instStupidTheta orig [mkClassPred icls [pat_ty]] }
; res <- tcExtendIdEnv1 name bndr_id thing_inside
; let minus'' = minus' { syn_res_wrap =
minus_wrap <.> syn_res_wrap minus' }
pat' = NPlusKPat (L nm_loc bndr_id) (L loc lit1') lit2'
ge' minus'' pat_ty
; return (pat', res) }
tc_pat _ _other_pat _ _ = panic "tc_pat"
unifyPatType :: Outputable a => a -> TcType -> ExpSigmaType -> TcM TcCoercion
unifyPatType thing actual_ty expected_ty
= do { coi <- unifyExpType (Just thing) actual_ty expected_ty
; return (mkTcSymCo coi) }
tcConPat :: PatEnv -> Located Name
-> ExpSigmaType
-> HsConPatDetails Name -> TcM a
-> TcM (Pat TcId, a)
tcConPat penv con_lname@(L _ con_name) pat_ty arg_pats thing_inside
= do { con_like <- tcLookupConLike con_name
; case con_like of
RealDataCon data_con -> tcDataConPat penv con_lname data_con
pat_ty arg_pats thing_inside
PatSynCon pat_syn -> tcPatSynPat penv con_lname pat_syn
pat_ty arg_pats thing_inside
}
tcDataConPat :: PatEnv -> Located Name -> DataCon
-> ExpSigmaType
-> HsConPatDetails Name -> TcM a
-> TcM (Pat TcId, a)
tcDataConPat penv (L con_span con_name) data_con pat_ty arg_pats thing_inside
= do { let tycon = dataConTyCon data_con
(univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _)
= dataConFullSig data_con
header = L con_span (RealDataCon data_con)
; (wrap, ctxt_res_tys) <- matchExpectedConTy penv tycon pat_ty
; pat_ty <- readExpType pat_ty
; setSrcSpan con_span $ addDataConStupidTheta data_con ctxt_res_tys
; let all_arg_tys = eqSpecPreds eq_spec ++ theta ++ arg_tys
; checkExistentials ex_tvs all_arg_tys penv
; (tenv, ex_tvs') <- tcInstSuperSkolTyVarsX
(zipTvSubst univ_tvs ctxt_res_tys) ex_tvs
; let
arg_tys' = substTys tenv arg_tys
; traceTc "tcConPat" (vcat [ ppr con_name
, pprTvBndrs univ_tvs
, pprTvBndrs ex_tvs
, ppr eq_spec
, ppr theta
, pprTvBndrs ex_tvs'
, ppr ctxt_res_tys
, ppr arg_tys'
, ppr arg_pats ])
; if null ex_tvs && null eq_spec && null theta
then do {
(arg_pats', res) <- tcConArgs (RealDataCon data_con) arg_tys'
arg_pats penv thing_inside
; let res_pat = ConPatOut { pat_con = header,
pat_tvs = [], pat_dicts = [],
pat_binds = emptyTcEvBinds,
pat_args = arg_pats',
pat_arg_tys = ctxt_res_tys,
pat_wrap = idHsWrapper }
; return (mkHsWrapPat wrap res_pat pat_ty, res) }
else do
{ let theta' = substTheta tenv (eqSpecPreds eq_spec ++ theta)
no_equalities = not (any isNomEqPred theta')
skol_info = case pe_ctxt penv of
LamPat mc -> PatSkol (RealDataCon data_con) mc
LetPat {} -> UnkSkol
; gadts_on <- xoptM LangExt.GADTs
; families_on <- xoptM LangExt.TypeFamilies
; checkTc (no_equalities || gadts_on || families_on)
(text "A pattern match on a GADT requires the" <+>
text "GADTs or TypeFamilies language extension")
; given <- newEvVars theta'
; (ev_binds, (arg_pats', res))
<- checkConstraints skol_info ex_tvs' given $
tcConArgs (RealDataCon data_con) arg_tys' arg_pats penv thing_inside
; let res_pat = ConPatOut { pat_con = header,
pat_tvs = ex_tvs',
pat_dicts = given,
pat_binds = ev_binds,
pat_args = arg_pats',
pat_arg_tys = ctxt_res_tys,
pat_wrap = idHsWrapper }
; return (mkHsWrapPat wrap res_pat pat_ty, res)
} }
tcPatSynPat :: PatEnv -> Located Name -> PatSyn
-> ExpSigmaType
-> HsConPatDetails Name -> TcM a
-> TcM (Pat TcId, a)
tcPatSynPat penv (L con_span _) pat_syn pat_ty arg_pats thing_inside
= do { let (univ_tvs, req_theta, ex_tvs, prov_theta, arg_tys, ty) = patSynSig pat_syn
; (subst, univ_tvs') <- newMetaTyVars univ_tvs
; let all_arg_tys = ty : prov_theta ++ arg_tys
; checkExistentials ex_tvs all_arg_tys penv
; (tenv, ex_tvs') <- tcInstSuperSkolTyVarsX subst ex_tvs
; let ty' = substTy tenv ty
arg_tys' = substTys tenv arg_tys
prov_theta' = substTheta tenv prov_theta
req_theta' = substTheta tenv req_theta
; wrap <- tcSubTypeET (pe_orig penv) pat_ty ty'
; traceTc "tcPatSynPat" (ppr pat_syn $$
ppr pat_ty $$
ppr ty' $$
ppr ex_tvs' $$
ppr prov_theta' $$
ppr req_theta' $$
ppr arg_tys')
; prov_dicts' <- newEvVars prov_theta'
; let skol_info = case pe_ctxt penv of
LamPat mc -> PatSkol (PatSynCon pat_syn) mc
LetPat {} -> UnkSkol
; req_wrap <- instCall PatOrigin (mkTyVarTys univ_tvs') req_theta'
; traceTc "instCall" (ppr req_wrap)
; traceTc "checkConstraints {" Outputable.empty
; (ev_binds, (arg_pats', res))
<- checkConstraints skol_info ex_tvs' prov_dicts' $
tcConArgs (PatSynCon pat_syn) arg_tys' arg_pats penv thing_inside
; traceTc "checkConstraints }" (ppr ev_binds)
; let res_pat = ConPatOut { pat_con = L con_span $ PatSynCon pat_syn,
pat_tvs = ex_tvs',
pat_dicts = prov_dicts',
pat_binds = ev_binds,
pat_args = arg_pats',
pat_arg_tys = mkTyVarTys univ_tvs',
pat_wrap = req_wrap }
; pat_ty <- readExpType pat_ty
; return (mkHsWrapPat wrap res_pat pat_ty, res) }
matchExpectedPatTy :: (TcRhoType -> TcM (TcCoercionN, a))
-> PatEnv -> ExpSigmaType -> TcM (HsWrapper, a)
matchExpectedPatTy inner_match (PE { pe_orig = orig }) pat_ty
= do { pat_ty <- expTypeToType pat_ty
; (wrap, pat_rho) <- topInstantiate orig pat_ty
; (co, res) <- inner_match pat_rho
; traceTc "matchExpectedPatTy" (ppr pat_ty $$ ppr wrap)
; return (mkWpCastN (mkTcSymCo co) <.> wrap, res) }
matchExpectedConTy :: PatEnv
-> TyCon
-> ExpSigmaType
-> TcM (HsWrapper, [TcSigmaType])
matchExpectedConTy (PE { pe_orig = orig }) data_tc pat_ty
| Just (fam_tc, fam_args, co_tc) <- tyConFamInstSig_maybe data_tc
= do { pat_ty <- expTypeToType pat_ty
; (wrap, pat_ty) <- topInstantiate orig pat_ty
; (subst, tvs') <- newMetaTyVars (tyConTyVars data_tc)
; traceTc "matchExpectedConTy" (vcat [ppr data_tc,
ppr (tyConTyVars data_tc),
ppr fam_tc, ppr fam_args])
; co1 <- unifyType noThing (mkTyConApp fam_tc (substTys subst fam_args)) pat_ty
; let tys' = mkTyVarTys tvs'
co2 = mkTcUnbranchedAxInstCo co_tc tys' []
; return ( wrap <.> (mkWpCastR $
mkTcSubCo (mkTcSymCo co1) `mkTcTransCo` co2)
, tys') }
| otherwise
= do { pat_ty <- expTypeToType pat_ty
; (wrap, pat_rho) <- topInstantiate orig pat_ty
; (coi, tys) <- matchExpectedTyConApp data_tc pat_rho
; return (mkWpCastN (mkTcSymCo coi) <.> wrap, tys) }
tcConArgs :: ConLike -> [TcSigmaType]
-> Checker (HsConPatDetails Name) (HsConPatDetails Id)
tcConArgs con_like arg_tys (PrefixCon arg_pats) penv thing_inside
= do { checkTc (con_arity == no_of_args)
(arityErr "constructor" con_like con_arity no_of_args)
; let pats_w_tys = zipEqual "tcConArgs" arg_pats arg_tys
; (arg_pats', res) <- tcMultiple tcConArg pats_w_tys
penv thing_inside
; return (PrefixCon arg_pats', res) }
where
con_arity = conLikeArity con_like
no_of_args = length arg_pats
tcConArgs con_like arg_tys (InfixCon p1 p2) penv thing_inside
= do { checkTc (con_arity == 2)
(arityErr "constructor" con_like con_arity 2)
; let [arg_ty1,arg_ty2] = arg_tys
; ([p1',p2'], res) <- tcMultiple tcConArg [(p1,arg_ty1),(p2,arg_ty2)]
penv thing_inside
; return (InfixCon p1' p2', res) }
where
con_arity = conLikeArity con_like
tcConArgs con_like arg_tys (RecCon (HsRecFields rpats dd)) penv thing_inside
= do { (rpats', res) <- tcMultiple tc_field rpats penv thing_inside
; return (RecCon (HsRecFields rpats' dd), res) }
where
tc_field :: Checker (LHsRecField Name (LPat Name))
(LHsRecField TcId (LPat TcId))
tc_field (L l (HsRecField (L loc (FieldOcc (L lr rdr) sel)) pat pun)) penv
thing_inside
= do { sel' <- tcLookupId sel
; pat_ty <- setSrcSpan loc $ find_field_ty (occNameFS $ rdrNameOcc rdr)
; (pat', res) <- tcConArg (pat, pat_ty) penv thing_inside
; return (L l (HsRecField (L loc (FieldOcc (L lr rdr) sel')) pat'
pun), res) }
find_field_ty :: FieldLabelString -> TcM TcType
find_field_ty lbl
= case [ty | (fl, ty) <- field_tys, flLabel fl == lbl] of
[] -> failWith (badFieldCon con_like lbl)
(pat_ty : extras) -> do
traceTc "find_field" (ppr pat_ty <+> ppr extras)
ASSERT( null extras ) (return pat_ty)
field_tys :: [(FieldLabel, TcType)]
field_tys = zip (conLikeFieldLabels con_like) arg_tys
tcConArg :: Checker (LPat Name, TcSigmaType) (LPat Id)
tcConArg (arg_pat, arg_ty) penv thing_inside
= tc_lpat arg_pat (mkCheckExpType arg_ty) penv thing_inside
addDataConStupidTheta :: DataCon -> [TcType] -> TcM ()
addDataConStupidTheta data_con inst_tys
| null stupid_theta = return ()
| otherwise = instStupidTheta origin inst_theta
where
origin = OccurrenceOf (dataConName data_con)
stupid_theta = dataConStupidTheta data_con
univ_tvs = dataConUnivTyVars data_con
tenv = zipTvSubst univ_tvs (takeList univ_tvs inst_tys)
inst_theta = substTheta tenv stupid_theta
maybeWrapPatCtxt :: Pat Name -> (TcM a -> TcM b) -> TcM a -> TcM b
maybeWrapPatCtxt pat tcm thing_inside
| not (worth_wrapping pat) = tcm thing_inside
| otherwise = addErrCtxt msg $ tcm $ popErrCtxt thing_inside
where
worth_wrapping (VarPat {}) = False
worth_wrapping (ParPat {}) = False
worth_wrapping (AsPat {}) = False
worth_wrapping _ = True
msg = hang (text "In the pattern:") 2 (ppr pat)
checkExistentials :: [TyVar]
-> [Type]
-> PatEnv -> TcM ()
checkExistentials ex_tvs tys _
| all (not . (`elemVarSet` tyCoVarsOfTypes tys)) ex_tvs = return ()
checkExistentials _ _ (PE { pe_ctxt = LetPat {}}) = failWithTc existentialLetPat
checkExistentials _ _ (PE { pe_ctxt = LamPat ProcExpr }) = failWithTc existentialProcPat
checkExistentials _ _ (PE { pe_lazy = True }) = failWithTc existentialLazyPat
checkExistentials _ _ _ = return ()
existentialLazyPat :: SDoc
existentialLazyPat
= hang (text "An existential or GADT data constructor cannot be used")
2 (text "inside a lazy (~) pattern")
existentialProcPat :: SDoc
existentialProcPat
= text "Proc patterns cannot use existential or GADT data constructors"
existentialLetPat :: SDoc
existentialLetPat
= vcat [text "My brain just exploded",
text "I can't handle pattern bindings for existential or GADT data constructors.",
text "Instead, use a case-expression, or do-notation, to unpack the constructor."]
badFieldCon :: ConLike -> FieldLabelString -> SDoc
badFieldCon con field
= hsep [text "Constructor" <+> quotes (ppr con),
text "does not have field", quotes (ppr field)]
polyPatSig :: TcType -> SDoc
polyPatSig sig_ty
= hang (text "Illegal polymorphic type signature in pattern:")
2 (ppr sig_ty)
lazyUnliftedPatErr :: OutputableBndr name => Pat name -> TcM ()
lazyUnliftedPatErr pat
= failWithTc $
hang (text "A lazy (~) pattern cannot contain unlifted types:")
2 (ppr pat)