#include "HsVersions.h"
import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
- ConDecl(..), Sig(..), , NewOrData(..),
- tyClDeclTyVars, isSynDecl, LConDecl,
- LTyClDecl, tcdName, LHsTyVarBndr, LHsContext
+ ConDecl(..), Sig(..), , NewOrData(..), ResType(..),
+ tyClDeclTyVars, isSynDecl, hsConArgs,
+ LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr
)
import HsTypes ( HsBang(..), getBangStrictness )
import BasicTypes ( RecFlag(..), StrictnessMark(..) )
import TcRnMonad
import TcEnv ( TyThing(..),
tcLookupLocated, tcLookupLocatedGlobal,
- tcExtendGlobalEnv, tcExtendKindEnv,
+ tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
tcExtendRecEnv, tcLookupTyVar )
import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles )
import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
- kcHsSigType, tcHsBangType, tcLHsConSig, tcDataKindSig )
-import TcMType ( newKindVar, checkValidTheta, checkValidType, checkFreeness,
+ kcHsSigType, tcHsBangType, tcLHsConResTy, tcDataKindSig )
+import TcMType ( newKindVar, checkValidTheta, checkValidType,
+ -- checkFreeness,
UserTypeCtxt(..), SourceTyCtxt(..) )
-import TcUnify ( unifyKind )
-import TcType ( TcKind, ThetaType, TcType, tyVarsOfType,
- mkArrowKind, liftedTypeKind, mkTyVarTys, tcEqTypes,
- tcSplitSigmaTy, tcEqType )
-import Type ( splitTyConApp_maybe, pprThetaArrow, pprParendType )
+import TcType ( TcKind, TcType, tyVarsOfType, mkPhiTy,
+ mkArrowKind, liftedTypeKind, mkTyVarTys,
+ tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
+import Type ( splitTyConApp_maybe,
+ -- pprParendType, pprThetaArrow
+ )
+import Kind ( mkArrowKinds, splitKindFunTys )
import Generics ( validGenericMethodType, canDoGenerics )
import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
import TyCon ( TyCon, ArgVrcs, AlgTyConRhs( AbstractTyCon ),
tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon,
- tyConStupidTheta, getSynTyConDefn, isSynTyCon, tyConName )
-import DataCon ( DataCon, dataConWrapId, dataConName, dataConSig,
- dataConFieldLabels, dataConOrigArgTys, dataConTyCon )
-import Type ( zipTopTvSubst, substTys )
+ tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName )
+import DataCon ( DataCon, dataConWrapId, dataConName,
+ dataConFieldLabels, dataConTyCon,
+ dataConTyVars, dataConFieldType, dataConResTys )
import Var ( TyVar, idType, idName )
-import VarSet ( elemVarSet )
-import Name ( Name )
+import VarSet ( elemVarSet, mkVarSet )
+import Name ( Name, getSrcLoc )
import Outputable
+import Maybe ( isJust )
+import Maybes ( expectJust )
+import Unify ( tcMatchTys, tcMatchTyX )
import Util ( zipLazy, isSingleton, notNull, sortLe )
import List ( partition )
-import SrcLoc ( Located(..), unLoc, getLoc )
+import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
import ListSetOps ( equivClasses )
+import List ( delete )
import Digraph ( SCC(..) )
import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
Opt_UnboxStrictFields ) )
------------------------------------------------------------------------
getInitialKind :: LTyClDecl Name -> TcM (Name, TcKind)
+-- Only for data type and class declarations
+-- Get as much info as possible from the data or class decl,
+-- so as to maximise usefulness of error messages
+getInitialKind (L _ decl)
+ = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
+ ; res_kind <- mk_res_kind decl
+ ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
+ where
+ mk_arg_kind (UserTyVar _) = newKindVar
+ mk_arg_kind (KindedTyVar _ kind) = return kind
+
+ mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
+ -- On GADT-style declarations we allow a kind signature
+ -- data T :: *->* where { ... }
+ mk_res_kind other = return liftedTypeKind
-getInitialKind decl
- = newKindVar `thenM` \ kind ->
- returnM (unLoc (tcdLName (unLoc decl)), kind)
----------------
kcSynDecls :: [SCC (LTyClDecl Name)]
= do { recSynErr decls; failM } -- Fail here to avoid error cascade
-- of out-of-scope tycons
+kindedTyVarKind (L _ (KindedTyVar _ k)) = k
+
------------------------------------------------------------------------
kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
-- Not used for type synonyms (see kcSynDecl)
; cons' <- mappM (wrapLocM kc_con_decl) cons
; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) }
where
- kc_con_decl (ConDecl name ex_tvs ex_ctxt details)
- = kcHsTyVars ex_tvs $ \ ex_tvs' ->
- do { ex_ctxt' <- kcHsContext ex_ctxt
- ; details' <- kc_con_details details
- ; return (ConDecl name ex_tvs' ex_ctxt' details')}
- kc_con_decl (GadtDecl name ty)
- = do { ty' <- kcHsSigType ty
- ; traceTc (text "kc_con_decl" <+> ppr name <+> ppr ty')
- ; return (GadtDecl name ty') }
+ kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
+ kcHsTyVars ex_tvs $ \ex_tvs' -> do
+ ex_ctxt' <- kcHsContext ex_ctxt
+ details' <- kc_con_details details
+ res' <- case res of
+ ResTyH98 -> return ResTyH98
+ ResTyGADT ty -> return . ResTyGADT =<< kcHsSigType ty
+ return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
kc_con_details (PrefixCon btys)
= do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs})
= kcTyClDeclBody decl $ \ tvs' ->
- do { ctxt' <- kcHsContext ctxt
+ do { is_boot <- tcIsHsBoot
+ ; checkTc (not is_boot) badBootClassDeclErr
+ ; ctxt' <- kcHsContext ctxt
; sigs' <- mappM (wrapLocM kc_sig) sigs
; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) }
where
- kc_sig (Sig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
- ; return (Sig nm op_ty') }
+ kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
+ ; return (TypeSig nm op_ty') }
kc_sig other_sig = return other_sig
kcTyClDecl decl@(ForeignType {})
kcTyClDeclBody :: TyClDecl Name
-> ([LHsTyVarBndr Name] -> TcM a)
-> TcM a
- -- Extend the env with bindings for the tyvars, taken from
- -- the kind of the tycon/class. Give it to the thing inside, and
- -- check the result kind matches
+-- getInitialKind has made a suitably-shaped kind for the type or class
+-- Unpack it, and attribute those kinds to the type variables
+-- Extend the env with bindings for the tyvars, taken from
+-- the kind of the tycon/class. Give it to the thing inside, and
+ -- check the result kind matches
kcTyClDeclBody decl thing_inside
= tcAddDeclCtxt decl $
- kcHsTyVars (tyClDeclTyVars decl) $ \ kinded_tvs ->
do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
- ; let tc_kind = case tc_ty_thing of { AThing k -> k }
- ;
- ; traceTc (text "kcbody" <+> ppr decl <+> ppr tc_kind <+> ppr (map kindedTyVarKind kinded_tvs) <+> ppr (result_kind decl))
- ; unifyKind tc_kind (foldr (mkArrowKind . kindedTyVarKind)
- (result_kind decl)
- kinded_tvs)
- ; thing_inside kinded_tvs }
- where
- result_kind (TyData { tcdKindSig = Just kind }) = kind
- result_kind other = liftedTypeKind
- -- On GADT-style declarations we allow a kind signature
- -- data T :: *->* where { ... }
-
-kindedTyVarKind (L _ (KindedTyVar _ k)) = k
+ ; let tc_kind = case tc_ty_thing of { AThing k -> k }
+ (kinds, _) = splitKindFunTys tc_kind
+ hs_tvs = tcdTyVars decl
+ kinded_tvs = ASSERT( length kinds >= length hs_tvs )
+ [ L loc (KindedTyVar (hsTyVarName tv) k)
+ | (L loc tv, k) <- zip hs_tvs kinds]
+ ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
\end{code}
= tcTyVarBndrs tvs $ \ tvs' -> do
{ extra_tvs <- tcDataKindSig mb_ksig
; let final_tvs = tvs' ++ extra_tvs
- ; stupid_theta <- tcStupidTheta ctxt cons
-
+ ; stupid_theta <- tcHsKindedContext ctxt
; want_generic <- doptM Opt_Generics
; unbox_strict <- doptM Opt_UnboxStrictFields
; gla_exts <- doptM Opt_GlasgowExts
; checkTc (not (null cons) || gla_exts || is_boot)
(emptyConDeclsErr tc_name)
+ -- Check that a newtype has exactly one constructor
+ ; checkTc (new_or_data == DataType || isSingleton cons)
+ (newtypeConError tc_name (length cons))
+
; tycon <- fixM (\ tycon -> do
{ data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
tycon final_tvs))
= AbstractTyCon -- "don't know"; hence Abstract
| otherwise
= case new_or_data of
- DataType -> mkDataTyConRhs stupid_theta data_cons
+ DataType -> mkDataTyConRhs data_cons
NewType -> ASSERT( isSingleton data_cons )
mkNewTyConRhs tycon (head data_cons)
- ; buildAlgTyCon tc_name final_tvs tc_rhs arg_vrcs is_rec
+ ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs arg_vrcs is_rec
(want_generic && canDoGenerics data_cons)
})
; return (ATyCon tycon)
arg_vrcs = calc_vrcs tc_name
is_rec = calc_isrec tc_name
h98_syntax = case cons of -- All constructors have same shape
- L _ (GadtDecl {}) : _ -> False
+ L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
other -> True
tcTyClDecl1 calc_vrcs calc_isrec
-> ConDecl Name -> TcM DataCon
tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
- (ConDecl name ex_tvs ex_ctxt details)
- = ASSERT( null ex_tvs && null (unLoc ex_ctxt) )
- do { let tc_datacon field_lbls arg_ty
+ (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
+ = do { let tc_datacon field_lbls arg_ty
= do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
; buildDataCon (unLoc name) False {- Prefix -}
True {- Vanilla -} [NotMarkedStrict]
(map unLoc field_lbls)
tc_tvs [] [arg_ty']
tycon (mkTyVarTys tc_tvs) }
+
+ -- Check that a newtype has no existential stuff
+ ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
+
; case details of
PrefixCon [arg_ty] -> tc_datacon [] arg_ty
- RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty }
+ RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
+ other -> failWithTc (newtypeFieldErr name (length (hsConArgs details)))
+ -- Check that the constructor has exactly one field
+ }
-tcConDecl unbox_strict DataType tycon tc_tvs -- Ordinary data types
- (ConDecl name ex_tvs ex_ctxt details)
- = tcTyVarBndrs ex_tvs $ \ ex_tvs' -> do
- { ex_ctxt' <- tcHsKindedContext ex_ctxt
+tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
+ (ConDecl name _ tvs ctxt details res_ty)
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { ctxt' <- tcHsKindedContext ctxt
+ ; (data_tc, res_ty_args) <- tcResultType tycon tc_tvs res_ty
; let
- is_vanilla = null ex_tvs && null (unLoc ex_ctxt)
- -- Vanilla iff no ex_tvs and no context
- -- Must check the context too because of
- -- implicit params; e.g.
- -- data T = (?x::Int) => MkT Int
+ con_tvs = case res_ty of
+ ResTyH98 -> tc_tvs ++ tvs'
+ ResTyGADT _ -> tryVanilla tvs' res_ty_args
+
+ -- Vanilla iff result type matches the quantified vars exactly,
+ -- and there is no existential context
+ -- Must check the context too because of implicit params; e.g.
+ -- data T = (?x::Int) => MkT Int
+ is_vanilla = res_ty_args `tcEqTypes` mkTyVarTys con_tvs
+ && null (unLoc ctxt)
tc_datacon is_infix field_lbls btys
- = do { let { bangs = map getBangStrictness btys }
+ = do { let bangs = map getBangStrictness btys
; arg_tys <- mappM tcHsBangType btys
; buildDataCon (unLoc name) is_infix is_vanilla
(argStrictness unbox_strict tycon bangs arg_tys)
(map unLoc field_lbls)
- (tc_tvs ++ ex_tvs')
- ex_ctxt'
- arg_tys
- tycon (mkTyVarTys tc_tvs) }
+ con_tvs ctxt' arg_tys
+ data_tc res_ty_args }
+ -- NB: we put data_tc, the type constructor gotten from the constructor
+ -- type signature into the data constructor; that way
+ -- checkValidDataCon can complain if it's wrong.
+
; case details of
PrefixCon btys -> tc_datacon False [] btys
- InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
- RecCon fields -> do { checkTc (null ex_tvs) (exRecConErr name)
- -- It's ok to have an implicit-parameter context
- -- for the data constructor, provided it binds
- -- no type variables
- ; let { (field_names, btys) = unzip fields }
- ; tc_datacon False field_names btys } }
-
-tcConDecl unbox_strict DataType tycon tc_tvs -- GADTs
- decl@(GadtDecl name con_ty)
- = do { traceTc (text "tcConDecl" <+> ppr name)
- ; (tvs, theta, bangs, arg_tys, data_tc, res_tys) <- tcLHsConSig con_ty
-
- ; traceTc (text "tcConDecl1" <+> ppr name)
- ; let -- Now dis-assemble the type, and check its form
- is_vanilla = null theta && mkTyVarTys tvs `tcEqTypes` res_tys
-
- -- Vanilla datacons guarantee to use the same
- -- type variables as the parent tycon
- (tvs', arg_tys', res_tys')
- | is_vanilla = (tc_tvs, substTys subst arg_tys, substTys subst res_tys)
- | otherwise = (tvs, arg_tys, res_tys)
- subst = zipTopTvSubst tvs (mkTyVarTys tc_tvs)
-
- ; traceTc (text "tcConDecl3" <+> ppr name)
- ; buildDataCon (unLoc name) False {- Not infix -} is_vanilla
- (argStrictness unbox_strict tycon bangs arg_tys)
- [{- No field labels -}]
- tvs' theta arg_tys' data_tc res_tys' }
- -- NB: we put data_tc, the type constructor gotten from the constructor
- -- type signature into the data constructor; that way checkValidDataCon
- -- can complain if it's wrong.
+ InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
+ RecCon fields -> tc_datacon False field_names btys
+ where
+ (field_names, btys) = unzip fields
+
+ }
+
+tcResultType :: TyCon -> [TyVar] -> ResType Name -> TcM (TyCon, [TcType])
+tcResultType tycon tvs ResTyH98 = return (tycon, mkTyVarTys tvs)
+tcResultType _ _ (ResTyGADT res_ty) = tcLHsConResTy res_ty
+
+tryVanilla :: [TyVar] -> [TcType] -> [TyVar]
+-- (tryVanilla tvs tys) returns a permutation of tvs.
+-- It tries to re-order the tvs so that it exactly
+-- matches the [Type], if that is possible
+tryVanilla tvs (ty:tys) | Just tv <- tcGetTyVar_maybe ty -- The type is a tyvar
+ , tv `elem` tvs -- That tyvar is in the list
+ = tv : tryVanilla (delete tv tvs) tys
+tryVanilla tvs tys = tvs -- Fall through case
--------------------
-tcStupidTheta :: LHsContext Name -> [LConDecl Name] -> TcM (Maybe ThetaType)
--- For GADTs we don't allow a context on the data declaration
--- whereas for standard Haskell style data declarations, we do
-tcStupidTheta ctxt (L _ (ConDecl _ _ _ _) : _)
- = do { theta <- tcHsKindedContext ctxt; return (Just theta) }
-tcStupidTheta ctxt other -- Includes an empty constructor list
- = ASSERT( null (unLoc ctxt) ) return Nothing
-------------------
argStrictness :: Bool -- True <=> -funbox-strict_fields
}
-------------------------
+-- For data types declared with record syntax, we require
+-- that each constructor that has a field 'f'
+-- (a) has the same result type
+-- (b) has the same type for 'f'
+-- module alpha conversion of the quantified type variables
+-- of the constructor.
+
checkValidTyCon :: TyCon -> TcM ()
checkValidTyCon tc
| isSynTyCon tc
mappM_ check_fields groups
where
- syn_ctxt = TySynCtxt name
- name = tyConName tc
- (_, syn_rhs) = getSynTyConDefn tc
- data_cons = tyConDataCons tc
+ syn_ctxt = TySynCtxt name
+ name = tyConName tc
+ syn_rhs = synTyConRhs tc
+ data_cons = tyConDataCons tc
groups = equivClasses cmp_fld (concatMap get_fields data_cons)
cmp_fld (f1,_) (f2,_) = f1 `compare` f2
- get_fields con = dataConFieldLabels con `zip` dataConOrigArgTys con
+ get_fields con = dataConFieldLabels con `zip` repeat con
-- dataConFieldLabels may return the empty list, which is fine
- check_fields fields@((first_field_label, field_ty) : other_fields)
+ -- XXX - autrijus - Make this far more complex to acommodate
+ -- for different return types. Add res_ty to the mix,
+ -- comparing them in two steps, all for good error messages.
+ -- Plan: Use Unify.tcMatchTys to compare the first candidate's
+ -- result type against other candidates' types (check bothways).
+ -- If they magically agrees, take the substitution and
+ -- apply them to the latter ones, and see if they match perfectly.
+ -- check_fields fields@((first_field_label, field_ty) : other_fields)
+ check_fields fields@((label, con1) : other_fields)
-- These fields all have the same name, but are from
-- different constructors in the data type
- = -- Check that all the fields in the group have the same type
+ = recoverM (return ()) $ mapM_ checkOne other_fields
+ -- Check that all the fields in the group have the same type
-- NB: this check assumes that all the constructors of a given
-- data type use the same type variables
- checkTc (all (tcEqType field_ty . snd) other_fields)
- (fieldTypeMisMatch first_field_label)
+ where
+ tvs1 = mkVarSet (dataConTyVars con1)
+ res1 = dataConResTys con1
+ fty1 = dataConFieldType con1 label
+
+ checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
+ = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
+ ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
+ where
+ tvs2 = mkVarSet (dataConTyVars con2)
+ res2 = dataConResTys con2
+ fty2 = dataConFieldType con2 label
+
+checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
+ = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
+ ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
+ where
+ mb_subst1 = tcMatchTys tvs1 res1 res2
+ mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
-------------------------------
checkValidDataCon :: TyCon -> DataCon -> TcM ()
checkValidDataCon tc con
- = addErrCtxt (dataConCtxt con) $
+ = setSrcSpan (srcLocSpan (getSrcLoc con)) $
+ addErrCtxt (dataConCtxt con) $
do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
; checkValidType ctxt (idType (dataConWrapId con)) }
; checkValidTheta (ClassSCCtxt (className cls)) theta
-- Check the class operations
- ; mappM_ check_op op_stuff
+ ; mappM_ (check_op gla_exts) op_stuff
-- Check that if the class has generic methods, then the
-- class has only one parameter. We can't do generic
unary = isSingleton tyvars
no_generics = null [() | (_, GenDefMeth) <- op_stuff]
- check_op (sel_id, dm)
+ check_op gla_exts (sel_id, dm)
= addErrCtxt (classOpCtxt sel_id tau) $ do
{ checkValidTheta SigmaCtxt (tail theta)
-- The 'tail' removes the initial (C a) from the
where
op_name = idName sel_id
op_ty = idType sel_id
- (_,theta,tau) = tcSplitSigmaTy op_ty
-
+ (_,theta1,tau1) = tcSplitSigmaTy op_ty
+ (_,theta2,tau2) = tcSplitSigmaTy tau1
+ (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
+ | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
+ -- Ugh! The function might have a type like
+ -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
+ -- With -fglasgow-exts, we want to allow this, even though the inner
+ -- forall has an (Eq a) constraint. Whereas in general, each constraint
+ -- in the context of a for-all must mention at least one quantified
+ -- type variable. What a mess!
---------------------------------------------------------------------
-fieldTypeMisMatch field_name
- = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
+resultTypeMisMatch field_name con1 con2
+ = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
+ ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
+ nest 2 $ ptext SLIT("but have different result types")]
+fieldTypeMisMatch field_name con1 con2
+ = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
+ ptext SLIT("give different types for field"), quotes (ppr field_name)]
-dataConCtxt con = sep [ptext SLIT("When checking the data constructor:"),
- nest 2 (ex_part <+> pprThetaArrow ex_theta <+> ppr con <+> arg_part)]
- where
- (ex_tvs, ex_theta, arg_tys, _, _) = dataConSig con
- ex_part | null ex_tvs = empty
- | otherwise = ptext SLIT("forall") <+> hsep (map ppr ex_tvs) <> dot
- -- The 'ex_theta' part could be non-empty, if the user (bogusly) wrote
- -- data T a = Eq a => T a a
- -- So we make sure to print it
-
- fields = dataConFieldLabels con
- arg_part | null fields = sep (map pprParendType arg_tys)
- | otherwise = braces (sep (punctuate comma
- [ ppr n <+> dcolon <+> ppr ty
- | (n,ty) <- fields `zip` arg_tys]))
+dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
where
le (L l1 _) (L l2 _) = l1 <= l2
-exRecConErr name
- = ptext SLIT("Can't combine named fields with locally-quantified type variables or context")
- $$
- (ptext SLIT("In the declaration of data constructor") <+> ppr name)
-
badDataConTyCon data_con
= hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
= vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
, nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
+newtypeConError tycon n
+ = sep [ptext SLIT("A newtype must have exactly one constructor,"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
+
+newtypeExError con
+ = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
+
+newtypeFieldErr con_name n_flds
+ = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
+
emptyConDeclsErr tycon
= sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
- nest 4 (ptext SLIT("(-fglasgow-exts permits this)"))]
+ nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]
+
+badBootClassDeclErr = ptext SLIT("Illegal class declaration in hs-boot file")
\end{code}
projects / ghc-hetmet.git / blobdiff