module TcPatSyn ( tcPatSynSig, tcInferPatSynDecl, tcCheckPatSynDecl
, tcPatSynBuilderBind, tcPatSynBuilderOcc, nonBidirectionalErr
) where
import HsSyn
import TcPat
import TcHsType( tcImplicitTKBndrs, tcExplicitTKBndrs
, tcHsContext, tcHsLiftedType, tcHsOpenType )
import TcRnMonad
import TcEnv
import TcMType
import TysPrim
import TysWiredIn ( levityTy )
import Name
import SrcLoc
import PatSyn
import NameSet
import Panic
import Outputable
import FastString
import Var
import Id
import IdInfo( RecSelParent(..))
import TcBinds
import BasicTypes
import TcSimplify
import TcUnify
import TcType
import TcEvidence
import BuildTyCl
import VarSet
import MkId
import TcTyDecls
import ConLike
import FieldLabel
#if __GLASGOW_HASKELL__ < 709
import Data.Monoid( mconcat, mappend, mempty )
#endif
import Bag
import Util
import Data.Maybe
import Control.Monad ( unless, zipWithM )
import Data.List( partition )
import Pair( Pair(..) )
#include "HsVersions.h"
tcPatSynSig :: Name -> LHsSigType Name -> TcM TcPatSynInfo
tcPatSynSig name sig_ty
| HsIB { hsib_vars = implicit_hs_tvs
, hsib_body = hs_ty } <- sig_ty
, (univ_hs_tvs, hs_req, hs_ty1) <- splitLHsSigmaTy hs_ty
, (ex_hs_tvs, hs_prov, hs_ty2) <- splitLHsSigmaTy hs_ty1
, (hs_arg_tys, hs_body_ty) <- splitHsFunType hs_ty2
= do { (implicit_tvs, (univ_tvs, req, ex_tvs, prov, arg_tys, body_ty))
<- solveEqualities $
tcImplicitTKBndrs implicit_hs_tvs $
tcExplicitTKBndrs univ_hs_tvs $ \ univ_tvs ->
tcExplicitTKBndrs ex_hs_tvs $ \ ex_tvs ->
do { req <- tcHsContext hs_req
; prov <- tcHsContext hs_prov
; arg_tys <- mapM tcHsOpenType (hs_arg_tys :: [LHsType Name])
; body_ty <- tcHsLiftedType hs_body_ty
; let bound_tvs
= unionVarSets [ allBoundVariabless req
, allBoundVariabless prov
, allBoundVariabless (body_ty : arg_tys)
]
; return ( (univ_tvs, req, ex_tvs, prov, arg_tys, body_ty)
, bound_tvs) }
; implicit_tvs <- mapM zonkTcTyCoVarBndr implicit_tvs
; univ_tvs <- mapM zonkTcTyCoVarBndr univ_tvs
; ex_tvs <- mapM zonkTcTyCoVarBndr ex_tvs
; req <- zonkTcTypes req
; prov <- zonkTcTypes prov
; arg_tys <- zonkTcTypes arg_tys
; body_ty <- zonkTcType body_ty
; let free_kvs = tyCoVarsOfTelescope (implicit_tvs ++ univ_tvs ++ ex_tvs) $
tyCoVarsOfTypes (body_ty : req ++ prov ++ arg_tys)
; kvs <- quantifyTyVars emptyVarSet (Pair free_kvs emptyVarSet)
; let bad_tvs = filter (`elemVarSet` tyCoVarsOfType body_ty) ex_tvs
; unless (null bad_tvs) $ addErr $
hang (text "The result type" <+> quotes (ppr body_ty))
2 (text "mentions existential type variable" <> plural bad_tvs
<+> pprQuotedList bad_tvs)
; let univ_fvs = closeOverKinds $
(tyCoVarsOfTypes (body_ty : req) `extendVarSetList` univ_tvs)
(extra_univ, extra_ex) = partition (`elemVarSet` univ_fvs) $
kvs ++ implicit_tvs
; traceTc "tcTySig }" $
vcat [ text "implicit_tvs" <+> ppr implicit_tvs
, text "kvs" <+> ppr kvs
, text "extra_univ" <+> ppr extra_univ
, text "univ_tvs" <+> ppr univ_tvs
, text "req" <+> ppr req
, text "extra_ex" <+> ppr extra_ex
, text "ex_tvs_" <+> ppr ex_tvs
, text "prov" <+> ppr prov
, text "arg_tys" <+> ppr arg_tys
, text "body_ty" <+> ppr body_ty ]
; return (TPSI { patsig_name = name
, patsig_univ_tvs = extra_univ ++ univ_tvs
, patsig_req = req
, patsig_ex_tvs = extra_ex ++ ex_tvs
, patsig_prov = prov
, patsig_arg_tys = arg_tys
, patsig_body_ty = body_ty }) }
tcInferPatSynDecl :: PatSynBind Name Name
-> TcM (LHsBinds Id, TcGblEnv)
tcInferPatSynDecl PSB{ psb_id = lname@(L _ name), psb_args = details,
psb_def = lpat, psb_dir = dir }
= addPatSynCtxt lname $
do { traceTc "tcInferPatSynDecl {" $ ppr name
; tcCheckPatSynPat lpat
; let (arg_names, rec_fields, is_infix) = collectPatSynArgInfo details
; (tclvl, wanted, ((lpat', args), pat_ty))
<- pushLevelAndCaptureConstraints $
do { pat_ty <- newOpenInferExpType
; stuff <- tcPat PatSyn lpat pat_ty $
mapM tcLookupId arg_names
; pat_ty <- readExpType pat_ty
; return (stuff, pat_ty) }
; let named_taus = (name, pat_ty) : map (\arg -> (getName arg, varType arg)) args
; (qtvs, req_dicts, ev_binds) <- simplifyInfer tclvl False [] named_taus wanted
; let (ex_vars, prov_dicts) = tcCollectEx lpat'
univ_tvs = filter (not . (`elemVarSet` ex_vars)) qtvs
ex_tvs = varSetElems ex_vars
prov_theta = map evVarPred prov_dicts
req_theta = map evVarPred req_dicts
; traceTc "tcInferPatSynDecl }" $ ppr name
; tc_patsyn_finish lname dir False is_infix lpat'
(univ_tvs, req_theta, ev_binds, req_dicts)
(ex_tvs, mkTyVarTys ex_tvs, prov_theta, map EvId prov_dicts)
(map nlHsVar args, map idType args)
pat_ty rec_fields }
tcCheckPatSynDecl :: PatSynBind Name Name
-> TcPatSynInfo
-> TcM (LHsBinds Id, TcGblEnv)
tcCheckPatSynDecl PSB{ psb_id = lname@(L _ name), psb_args = details
, psb_def = lpat, psb_dir = dir }
TPSI{ patsig_univ_tvs = univ_tvs, patsig_prov = prov_theta
, patsig_ex_tvs = ex_tvs, patsig_req = req_theta
, patsig_arg_tys = arg_tys, patsig_body_ty = pat_ty }
= addPatSynCtxt lname $
do { let origin = PatOrigin
skol_info = SigSkol (PatSynCtxt name) (mkCheckExpType $
mkFunTys arg_tys pat_ty)
decl_arity = length arg_names
ty_arity = length arg_tys
(arg_names, rec_fields, is_infix) = collectPatSynArgInfo details
; traceTc "tcCheckPatSynDecl" $
vcat [ ppr univ_tvs, ppr req_theta, ppr ex_tvs
, ppr prov_theta, ppr arg_tys, ppr pat_ty ]
; checkTc (decl_arity == ty_arity)
(wrongNumberOfParmsErr name decl_arity ty_arity)
; tcCheckPatSynPat lpat
; req_dicts <- newEvVars req_theta
; (tclvl, wanted, (lpat', (ex_tvs', prov_dicts, args'))) <-
ASSERT2( equalLength arg_names arg_tys, ppr name $$ ppr arg_names $$ ppr arg_tys )
pushLevelAndCaptureConstraints $
tcExtendTyVarEnv univ_tvs $
tcPat PatSyn lpat (mkCheckExpType pat_ty) $
do { (subst, ex_tvs') <- if isUnidirectional dir
then newMetaTyVars ex_tvs
else newMetaSigTyVars ex_tvs
; prov_dicts <- mapM (emitWanted origin)
(substTheta (extendTCvInScopeList subst univ_tvs) prov_theta)
; args' <- zipWithM (tc_arg subst) arg_names arg_tys
; return (ex_tvs', prov_dicts, args') }
; (implics, ev_binds) <- buildImplicationFor tclvl skol_info univ_tvs req_dicts wanted
; _ <- simplifyTop (mkImplicWC implics)
; traceTc "tcCheckPatSynDecl }" $ ppr name
; tc_patsyn_finish lname dir True is_infix lpat'
(univ_tvs, req_theta, ev_binds, req_dicts)
(ex_tvs, mkTyVarTys ex_tvs', prov_theta, prov_dicts)
(args', arg_tys)
pat_ty rec_fields }
where
tc_arg :: TCvSubst -> Name -> Type -> TcM (LHsExpr TcId)
tc_arg subst arg_name arg_ty
= do {
arg_id <- tcLookupId arg_name
; coi <- unifyType (Just arg_id)
(idType arg_id)
(substTyUnchecked subst arg_ty)
; return (mkLHsWrapCo coi $ nlHsVar arg_id) }
collectPatSynArgInfo :: HsPatSynDetails (Located Name) -> ([Name], [Name], Bool)
collectPatSynArgInfo details =
case details of
PrefixPatSyn names -> (map unLoc names, [], False)
InfixPatSyn name1 name2 -> (map unLoc [name1, name2], [], True)
RecordPatSyn names ->
let (vars, sels) = unzip (map splitRecordPatSyn names)
in (vars, sels, False)
where
splitRecordPatSyn :: RecordPatSynField (Located Name) -> (Name, Name)
splitRecordPatSyn (RecordPatSynField { recordPatSynPatVar = L _ patVar
, recordPatSynSelectorId = L _ selId })
= (patVar, selId)
addPatSynCtxt :: Located Name -> TcM a -> TcM a
addPatSynCtxt (L loc name) thing_inside
= setSrcSpan loc $
addErrCtxt (text "In the declaration for pattern synonym"
<+> quotes (ppr name)) $
thing_inside
wrongNumberOfParmsErr :: Name -> Arity -> Arity -> SDoc
wrongNumberOfParmsErr name decl_arity ty_arity
= hang (text "Patten synonym" <+> quotes (ppr name) <+> ptext (sLit "has")
<+> speakNOf decl_arity (text "argument"))
2 (text "but its type signature has" <+> speakN ty_arity)
tc_patsyn_finish :: Located Name
-> HsPatSynDir Name
-> Bool
-> Bool
-> LPat Id
-> ([TcTyVar], [PredType], TcEvBinds, [EvVar])
-> ([TcTyVar], [TcType], [PredType], [EvTerm])
-> ([LHsExpr TcId], [TcType])
-> TcType
-> [Name]
-> TcM (LHsBinds Id, TcGblEnv)
tc_patsyn_finish lname dir has_sig is_infix lpat'
(univ_tvs, req_theta, req_ev_binds, req_dicts)
(ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys)
pat_ty field_labels
= do {
univ_tvs <- mapMaybeM zonkQuantifiedTyVar univ_tvs
; ex_tvs <- mapMaybeM zonkQuantifiedTyVar ex_tvs
; prov_theta <- zonkTcTypes prov_theta
; req_theta <- zonkTcTypes req_theta
; pat_ty <- zonkTcType pat_ty
; arg_tys <- zonkTcTypes arg_tys
; traceTc "tc_patsyn_finish {" $
ppr (unLoc lname) $$ ppr (unLoc lpat') $$
ppr (univ_tvs, req_theta, req_ev_binds, req_dicts) $$
ppr (ex_tvs, prov_theta, prov_dicts) $$
ppr args $$
ppr arg_tys $$
ppr pat_ty
; (matcher_id, matcher_bind) <- tcPatSynMatcher has_sig lname lpat'
(univ_tvs, req_theta, req_ev_binds, req_dicts)
(ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys)
pat_ty
; builder_id <- mkPatSynBuilderId has_sig dir lname
univ_tvs req_theta
ex_tvs prov_theta
arg_tys pat_ty
; let mkFieldLabel name = FieldLabel (occNameFS (nameOccName name)) False name
field_labels' = (map mkFieldLabel field_labels)
; let patSyn = mkPatSyn (unLoc lname) is_infix
(univ_tvs, req_theta)
(ex_tvs, prov_theta)
arg_tys
pat_ty
matcher_id builder_id
field_labels'
; let (sigs, selector_binds) =
unzip (mkPatSynRecSelBinds patSyn (patSynFieldLabels patSyn))
; let tything = AConLike (PatSynCon patSyn)
; tcg_env <-
tcExtendGlobalEnv [tything] $
tcRecSelBinds
(ValBindsOut (zip (repeat NonRecursive) selector_binds) sigs)
; traceTc "tc_patsyn_finish }" empty
; return (matcher_bind, tcg_env) }
tcPatSynMatcher :: Bool
-> Located Name
-> LPat Id
-> ([TcTyVar], ThetaType, TcEvBinds, [EvVar])
-> ([TcTyVar], [TcType], ThetaType, [EvTerm])
-> ([LHsExpr TcId], [TcType])
-> TcType
-> TcM ((Id, Bool), LHsBinds Id)
tcPatSynMatcher has_sig (L loc name) lpat
(univ_tvs, req_theta, req_ev_binds, req_dicts)
(ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys) pat_ty
= do { lev_uniq <- newUnique
; tv_uniq <- newUnique
; let lev_name = mkInternalName lev_uniq (mkTyVarOcc "rlev") loc
tv_name = mkInternalName tv_uniq (mkTyVarOcc "r") loc
lev_tv = mkTcTyVar lev_name levityTy (SkolemTv False)
lev = mkTyVarTy lev_tv
res_tv = mkTcTyVar tv_name (tYPE lev) (SkolemTv False)
is_unlifted = null args && null prov_dicts
res_ty = mkTyVarTy res_tv
(cont_args, cont_arg_tys)
| is_unlifted = ([nlHsVar voidPrimId], [voidPrimTy])
| otherwise = (args, arg_tys)
mk_sigma = if has_sig then mkSpecSigmaTy else mkInvSigmaTy
cont_ty = mk_sigma ex_tvs prov_theta $
mkFunTys cont_arg_tys res_ty
fail_ty = mkFunTy voidPrimTy res_ty
; matcher_name <- newImplicitBinder name mkMatcherOcc
; scrutinee <- newSysLocalId (fsLit "scrut") pat_ty
; cont <- newSysLocalId (fsLit "cont") cont_ty
; fail <- newSysLocalId (fsLit "fail") fail_ty
; let matcher_tau = mkFunTys [pat_ty, cont_ty, fail_ty] res_ty
matcher_sigma = mkInvSigmaTy (lev_tv:res_tv:univ_tvs) req_theta matcher_tau
matcher_id = mkExportedVanillaId matcher_name matcher_sigma
inst_wrap = mkWpEvApps prov_dicts <.> mkWpTyApps ex_tys
cont' = foldl nlHsApp (mkLHsWrap inst_wrap (nlHsVar cont)) cont_args
fail' = nlHsApps fail [nlHsVar voidPrimId]
args = map nlVarPat [scrutinee, cont, fail]
lwpat = noLoc $ WildPat pat_ty
cases = if isIrrefutableHsPat lpat
then [mkSimpleHsAlt lpat cont']
else [mkSimpleHsAlt lpat cont',
mkSimpleHsAlt lwpat fail']
body = mkLHsWrap (mkWpLet req_ev_binds) $
L (getLoc lpat) $
HsCase (nlHsVar scrutinee) $
MG{ mg_alts = L (getLoc lpat) cases
, mg_arg_tys = [pat_ty]
, mg_res_ty = res_ty
, mg_origin = Generated
}
body' = noLoc $
HsLam $
MG{ mg_alts = noLoc [mkSimpleMatch args body]
, mg_arg_tys = [pat_ty, cont_ty, res_ty]
, mg_res_ty = res_ty
, mg_origin = Generated
}
match = mkMatch [] (mkHsLams (lev_tv:res_tv:univ_tvs) req_dicts body')
(noLoc EmptyLocalBinds)
mg = MG{ mg_alts = L (getLoc match) [match]
, mg_arg_tys = []
, mg_res_ty = res_ty
, mg_origin = Generated
}
; let bind = FunBind{ fun_id = L loc matcher_id
, fun_matches = mg
, fun_co_fn = idHsWrapper
, bind_fvs = emptyNameSet
, fun_tick = [] }
matcher_bind = unitBag (noLoc bind)
; traceTc "tcPatSynMatcher" (ppr name $$ ppr (idType matcher_id))
; traceTc "tcPatSynMatcher" (ppr matcher_bind)
; return ((matcher_id, is_unlifted), matcher_bind) }
mkPatSynRecSelBinds :: PatSyn
-> [FieldLabel]
-> [(LSig Name, LHsBinds Name)]
mkPatSynRecSelBinds ps fields = map mkRecSel fields
where
mkRecSel fld_lbl =
case mkOneRecordSelector [PatSynCon ps] (RecSelPatSyn ps) fld_lbl of
(name, (_rec_flag, binds)) -> (name, binds)
isUnidirectional :: HsPatSynDir a -> Bool
isUnidirectional Unidirectional = True
isUnidirectional ImplicitBidirectional = False
isUnidirectional ExplicitBidirectional{} = False
mkPatSynBuilderId :: Bool
-> HsPatSynDir a -> Located Name
-> [TyVar] -> ThetaType
-> [TyVar] -> ThetaType
-> [Type] -> Type
-> TcM (Maybe (Id, Bool))
mkPatSynBuilderId has_sig dir (L _ name)
univ_tvs req_theta ex_tvs prov_theta
arg_tys pat_ty
| isUnidirectional dir
= return Nothing
| otherwise
= do { builder_name <- newImplicitBinder name mkBuilderOcc
; let qtvs = univ_tvs ++ ex_tvs
theta = req_theta ++ prov_theta
mk_sigma = if has_sig then mkSpecSigmaTy else mkInvSigmaTy
need_dummy_arg = isUnLiftedType pat_ty && null arg_tys && null theta
builder_sigma = add_void need_dummy_arg $
mk_sigma qtvs theta (mkFunTys arg_tys pat_ty)
builder_id = mkExportedVanillaId builder_name builder_sigma
; return (Just (builder_id, need_dummy_arg)) }
where
add_void :: Bool -> Type -> Type
add_void need_dummy_arg ty
| need_dummy_arg = mkFunTy voidPrimTy ty
| otherwise = ty
tcPatSynBuilderBind :: TcSigFun
-> PatSynBind Name Name
-> TcM (LHsBinds Id)
tcPatSynBuilderBind sig_fun PSB{ psb_id = L loc name, psb_def = lpat
, psb_dir = dir, psb_args = details }
| isUnidirectional dir
= return emptyBag
| isNothing mb_match_group
= setSrcSpan (getLoc lpat) $ failWithTc $
hang (text "Right-hand side of bidirectional pattern synonym cannot be used as an expression")
2 (ppr lpat)
| otherwise
= do { patsyn <- tcLookupPatSyn name
; traceTc "tcPatSynBuilderBind {" $ ppr patsyn
; let Just (builder_id, need_dummy_arg) = patSynBuilder patsyn
match_group' | need_dummy_arg = add_dummy_arg match_group
| otherwise = match_group
bind = FunBind { fun_id = L loc (idName builder_id)
, fun_matches = match_group'
, fun_co_fn = idHsWrapper
, bind_fvs = placeHolderNamesTc
, fun_tick = [] }
; sig <- get_builder_sig sig_fun name builder_id need_dummy_arg
; (builder_binds, _) <- tcPolyCheck NonRecursive emptyPragEnv sig (noLoc bind)
; traceTc "tcPatSynBuilderBind }" $ ppr builder_binds
; return builder_binds }
where
Just match_group = mb_match_group
mb_match_group
= case dir of
Unidirectional -> Nothing
ExplicitBidirectional explicit_mg -> Just explicit_mg
ImplicitBidirectional -> fmap mk_mg (tcPatToExpr args lpat)
mk_mg :: LHsExpr Name -> MatchGroup Name (LHsExpr Name)
mk_mg body = mkMatchGroupName Generated [builder_match]
where
builder_args = [L loc (VarPat (L loc n)) | L loc n <- args]
builder_match = mkMatch builder_args body (noLoc EmptyLocalBinds)
args = case details of
PrefixPatSyn args -> args
InfixPatSyn arg1 arg2 -> [arg1, arg2]
RecordPatSyn args -> map recordPatSynPatVar args
add_dummy_arg :: MatchGroup Name (LHsExpr Name)
-> MatchGroup Name (LHsExpr Name)
add_dummy_arg mg@(MG { mg_alts
= L l [L loc (Match NonFunBindMatch [] ty grhss)] })
= mg { mg_alts
= L l [L loc (Match NonFunBindMatch [nlWildPatName] ty grhss)] }
add_dummy_arg other_mg = pprPanic "add_dummy_arg" $
pprMatches (PatSyn :: HsMatchContext Name) other_mg
get_builder_sig :: TcSigFun -> Name -> Id -> Bool -> TcM TcIdSigInfo
get_builder_sig sig_fun name builder_id need_dummy_arg
| Just (TcPatSynSig sig) <- sig_fun name
, TPSI { patsig_univ_tvs = univ_tvs
, patsig_req = req
, patsig_ex_tvs = ex_tvs
, patsig_prov = prov
, patsig_arg_tys = arg_tys
, patsig_body_ty = body_ty } <- sig
=
return (TISI { sig_bndr = CompleteSig builder_id
, sig_skols = [(tyVarName tv, tv) | tv <- univ_tvs ++ ex_tvs]
, sig_theta = req ++ prov
, sig_tau = add_void need_dummy_arg $
mkFunTys arg_tys body_ty
, sig_ctxt = PatSynCtxt name
, sig_loc = getSrcSpan name })
| otherwise
=
instTcTySigFromId builder_id
tcPatSynBuilderOcc :: PatSyn -> TcM (HsExpr TcId, TcSigmaType)
tcPatSynBuilderOcc ps
| Just (builder_id, add_void_arg) <- builder
, let builder_expr = HsVar (noLoc builder_id)
builder_ty = idType builder_id
= return $
if add_void_arg
then ( HsApp (noLoc $ builder_expr) (nlHsVar voidPrimId)
, tcFunResultTy builder_ty )
else (builder_expr, builder_ty)
| otherwise
= nonBidirectionalErr name
where
name = patSynName ps
builder = patSynBuilder ps
tcCheckPatSynPat :: LPat Name -> TcM ()
tcCheckPatSynPat = go
where
go :: LPat Name -> TcM ()
go = addLocM go1
go1 :: Pat Name -> TcM ()
go1 (ConPatIn _ info) = mapM_ go (hsConPatArgs info)
go1 VarPat{} = return ()
go1 WildPat{} = return ()
go1 p@(AsPat _ _) = asPatInPatSynErr p
go1 (LazyPat pat) = go pat
go1 (ParPat pat) = go pat
go1 (BangPat pat) = go pat
go1 (PArrPat pats _) = mapM_ go pats
go1 (ListPat pats _ _) = mapM_ go pats
go1 (TuplePat pats _ _) = mapM_ go pats
go1 LitPat{} = return ()
go1 NPat{} = return ()
go1 (SigPatIn pat _) = go pat
go1 (ViewPat _ pat _) = go pat
go1 p@SplicePat{} = thInPatSynErr p
go1 p@NPlusKPat{} = nPlusKPatInPatSynErr p
go1 ConPatOut{} = panic "ConPatOut in output of renamer"
go1 SigPatOut{} = panic "SigPatOut in output of renamer"
go1 CoPat{} = panic "CoPat in output of renamer"
asPatInPatSynErr :: OutputableBndr name => Pat name -> TcM a
asPatInPatSynErr pat
= failWithTc $
hang (text "Pattern synonym definition cannot contain as-patterns (@):")
2 (ppr pat)
thInPatSynErr :: OutputableBndr name => Pat name -> TcM a
thInPatSynErr pat
= failWithTc $
hang (text "Pattern synonym definition cannot contain Template Haskell:")
2 (ppr pat)
nPlusKPatInPatSynErr :: OutputableBndr name => Pat name -> TcM a
nPlusKPatInPatSynErr pat
= failWithTc $
hang (text "Pattern synonym definition cannot contain n+k-pattern:")
2 (ppr pat)
nonBidirectionalErr :: Outputable name => name -> TcM a
nonBidirectionalErr name = failWithTc $
text "non-bidirectional pattern synonym"
<+> quotes (ppr name) <+> text "used in an expression"
tcPatToExpr :: [Located Name] -> LPat Name -> Maybe (LHsExpr Name)
tcPatToExpr args = go
where
lhsVars = mkNameSet (map unLoc args)
go :: LPat Name -> Maybe (LHsExpr Name)
go (L loc (ConPatIn (L _ con) info))
= do { exprs <- mapM go (hsConPatArgs info)
; return $ L loc $
foldl (\x y -> HsApp (L loc x) y) (HsVar (L loc con)) exprs }
go (L _ (SigPatIn pat _)) = go pat
go (L loc p) = fmap (L loc) $ go1 p
go1 :: Pat Name -> Maybe (HsExpr Name)
go1 (VarPat (L l var))
| var `elemNameSet` lhsVars = return $ HsVar (L l var)
| otherwise = Nothing
go1 (LazyPat pat) = fmap HsPar $ go pat
go1 (ParPat pat) = fmap HsPar $ go pat
go1 (BangPat pat) = fmap HsPar $ go pat
go1 (PArrPat pats ptt) = do { exprs <- mapM go pats
; return $ ExplicitPArr ptt exprs }
go1 (ListPat pats ptt reb) = do { exprs <- mapM go pats
; return $ ExplicitList ptt (fmap snd reb) exprs }
go1 (TuplePat pats box _) = do { exprs <- mapM go pats
; return $ ExplicitTuple
(map (noLoc . Present) exprs) box }
go1 (LitPat lit) = return $ HsLit lit
go1 (NPat (L _ n) Nothing _ _) = return $ HsOverLit n
go1 (NPat (L _ n) (Just neg) _ _)= return $ unLoc $ nlHsSyntaxApps neg [noLoc (HsOverLit n)]
go1 (ConPatOut{}) = panic "ConPatOut in output of renamer"
go1 (SigPatOut{}) = panic "SigPatOut in output of renamer"
go1 (CoPat{}) = panic "CoPat in output of renamer"
go1 _ = Nothing
tcCollectEx :: LPat Id -> (TyVarSet, [EvVar])
tcCollectEx pat = go pat
where
go :: LPat Id -> (TyVarSet, [EvVar])
go = go1 . unLoc
go1 :: Pat Id -> (TyVarSet, [EvVar])
go1 (LazyPat p) = go p
go1 (AsPat _ p) = go p
go1 (ParPat p) = go p
go1 (BangPat p) = go p
go1 (ListPat ps _ _) = mconcat . map go $ ps
go1 (TuplePat ps _ _) = mconcat . map go $ ps
go1 (PArrPat ps _) = mconcat . map go $ ps
go1 (ViewPat _ p _) = go p
go1 con@ConPatOut{} = mappend (mkVarSet (pat_tvs con), pat_dicts con) $
goConDetails $ pat_args con
go1 (SigPatOut p _) = go p
go1 (CoPat _ p _) = go1 p
go1 (NPlusKPat n k _ geq subtract _)
= pprPanic "TODO: NPlusKPat" $ ppr n $$ ppr k $$ ppr geq $$ ppr subtract
go1 _ = mempty
goConDetails :: HsConPatDetails Id -> (TyVarSet, [EvVar])
goConDetails (PrefixCon ps) = mconcat . map go $ ps
goConDetails (InfixCon p1 p2) = go p1 `mappend` go p2
goConDetails (RecCon HsRecFields{ rec_flds = flds })
= mconcat . map goRecFd $ flds
goRecFd :: LHsRecField Id (LPat Id) -> (TyVarSet, [EvVar])
goRecFd (L _ HsRecField{ hsRecFieldArg = p }) = go p