\begin{code}
module TcTyClsDecls (
- tcTyAndClassDecls
+ tcTyAndClassDecls, tcIdxTyInstDecl
) where
#include "HsVersions.h"
import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
- ConDecl(..), Sig(..), , NewOrData(..), ResType(..),
- tyClDeclTyVars, isSynDecl, hsConArgs,
- LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr
+ ConDecl(..), Sig(..), NewOrData(..), ResType(..),
+ tyClDeclTyVars, isSynDecl, isClassDecl, isIdxTyDecl,
+ isKindSigDecl, hsConArgs, LTyClDecl, tcdName,
+ hsTyVarName, LHsTyVarBndr, LHsType, HsType(..),
+ mkHsAppTy
)
-import HsTypes ( HsBang(..), getBangStrictness )
+import HsTypes ( HsBang(..), getBangStrictness, hsLTyVarNames )
import BasicTypes ( RecFlag(..), StrictnessMark(..) )
import HscTypes ( implicitTyThings, ModDetails )
import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
import TcRnMonad
import TcEnv ( TyThing(..),
tcLookupLocated, tcLookupLocatedGlobal,
- tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
- tcExtendRecEnv, tcLookupTyVar )
-import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles )
+ tcExtendGlobalEnv, tcExtendKindEnv,
+ tcExtendKindEnvTvs, newFamInstTyConName,
+ tcExtendRecEnv, tcLookupTyVar, tcLookupLocatedTyCon )
+import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
- kcHsSigType, tcHsBangType, tcLHsConResTy, tcDataKindSig )
+ kcHsSigType, tcHsBangType, tcLHsConResTy,
+ tcDataKindSig, kcCheckHsType )
import TcMType ( newKindVar, checkValidTheta, checkValidType,
-- checkFreeness,
UserTypeCtxt(..), SourceTyCtxt(..) )
-import TcType ( TcKind, TcType, tyVarsOfType, mkPhiTy,
+import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
mkArrowKind, liftedTypeKind, mkTyVarTys,
tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
-import Type ( splitTyConApp_maybe,
+import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy,
+ newTyConInstRhs, isLiftedTypeKind, Kind
-- 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, synTyConRhs, isSynTyCon, tyConName )
-import DataCon ( DataCon, dataConWrapId, dataConName,
- dataConFieldLabels, dataConTyCon,
- dataConTyVars, dataConFieldType, dataConResTys )
+import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
+ OpenNewTyCon ),
+ SynTyConRhs( OpenSynTyCon, SynonymTyCon ),
+ tyConDataCons, mkForeignTyCon, isProductTyCon,
+ isRecursiveTyCon, isOpenTyCon,
+ tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
+ isNewTyCon, isDataTyCon, tyConKind,
+ setTyConArgPoss )
+import DataCon ( DataCon, dataConUserType, dataConName,
+ dataConFieldLabels, dataConTyCon, dataConAllTyVars,
+ dataConFieldType, dataConResTys )
import Var ( TyVar, idType, idName )
import VarSet ( elemVarSet, mkVarSet )
import Name ( Name, getSrcLoc )
import Outputable
-import Maybe ( isJust )
+import Maybe ( isJust, fromJust, isNothing, catMaybes )
import Maybes ( expectJust )
+import Monad ( unless )
import Unify ( tcMatchTys, tcMatchTyX )
import Util ( zipLazy, isSingleton, notNull, sortLe )
-import List ( partition )
-import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
-import ListSetOps ( equivClasses )
-import List ( delete )
+import List ( partition, elemIndex )
+import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan,
+ srcSpanStart )
+import ListSetOps ( equivClasses, minusList )
import Digraph ( SCC(..) )
import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
- Opt_UnboxStrictFields ) )
+ Opt_UnboxStrictFields, Opt_IndexedTypes ) )
\end{code}
to check all the side conditions on validity. We could not
do this before because we were in a mutually recursive knot.
-
+Identification of recursive TyCons
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
-@TyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s.
+@TyThing@s.
+
+Identifying a TyCon as recursive serves two purposes
+
+1. Avoid infinite types. Non-recursive newtypes are treated as
+"transparent", like type synonyms, after the type checker. If we did
+this for all newtypes, we'd get infinite types. So we figure out for
+each newtype whether it is "recursive", and add a coercion if so. In
+effect, we are trying to "cut the loops" by identifying a loop-breaker.
+
+2. Avoid infinite unboxing. This is nothing to do with newtypes.
+Suppose we have
+ data T = MkT Int T
+ f (MkT x t) = f t
+Well, this function diverges, but we don't want the strictness analyser
+to diverge. But the strictness analyser will diverge because it looks
+deeper and deeper into the structure of T. (I believe there are
+examples where the function does something sane, and the strictness
+analyser still diverges, but I can't see one now.)
+
+Now, concerning (1), the FC2 branch currently adds a coercion for ALL
+newtypes. I did this as an experiment, to try to expose cases in which
+the coercions got in the way of optimisations. If it turns out that we
+can indeed always use a coercion, then we don't risk recursive types,
+and don't need to figure out what the loop breakers are.
+
+For newtype *families* though, we will always have a coercion, so they
+are always loop breakers! So you can easily adjust the current
+algorithm by simply treating all newtype families as loop breakers (and
+indeed type families). I think.
\begin{code}
tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
-> TcM TcGblEnv -- Input env extended by types and classes
-- and their implicit Ids,DataCons
-tcTyAndClassDecls boot_details decls
- = do { -- First check for cyclic type synonysm or classes
+tcTyAndClassDecls boot_details allDecls
+ = do { -- Omit instances of indexed types; they are handled together
+ -- with the *heads* of class instances
+ ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
+
+ -- First check for cyclic type synonysm or classes
-- See notes with checkCycleErrs
- checkCycleErrs decls
+ ; checkCycleErrs decls
; mod <- getModule
; traceTc (text "tcTyAndCl" <+> ppr mod)
; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
- do { let { -- Calculate variances and rec-flag
- ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc) decls }
-
+ do { let { -- Seperate ordinary synonyms from all other type and
+ -- class declarations and add all associated type
+ -- declarations from type classes. The latter is
+ -- required so that the temporary environment for the
+ -- knot includes all associated family declarations.
+ ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
+ decls
+ ; alg_at_decls = concatMap addATs alg_decls
+ }
-- Extend the global env with the knot-tied results
-- for data types and classes
--
- -- We must populate the environment with the loop-tied T's right
- -- away, because the kind checker may "fault in" some type
- -- constructors that recursively mention T
- ; let { gbl_things = mkGlobalThings alg_decls rec_alg_tyclss }
+ -- We must populate the environment with the loop-tied
+ -- T's right away, because the kind checker may "fault
+ -- in" some type constructors that recursively
+ -- mention T
+ ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
; tcExtendRecEnv gbl_things $ do
-- Kind-check the declarations
{ (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
- ; let { calc_vrcs = calcTyConArgVrcs (rec_syn_tycons ++ rec_alg_tyclss)
+ ; let { -- Calculate rec-flag
; calc_rec = calcRecFlags boot_details rec_alg_tyclss
- ; tc_decl = addLocM (tcTyClDecl calc_vrcs calc_rec) }
+ ; tc_decl = addLocM (tcTyClDecl calc_rec) }
-- Type-check the type synonyms, and extend the envt
- ; syn_tycons <- tcSynDecls calc_vrcs kc_syn_decls
+ ; syn_tycons <- tcSynDecls kc_syn_decls
; tcExtendGlobalEnv syn_tycons $ do
-- Type-check the data types and classes
{ alg_tyclss <- mappM tc_decl kc_alg_decls
- ; return (syn_tycons, alg_tyclss)
+ ; return (syn_tycons, concat alg_tyclss)
}}})
-- Finished with knot-tying now
-- Extend the environment with the finished things
-- Add the implicit things;
-- we want them in the environment because
-- they may be mentioned in interface files
+ -- NB: All associated types and their implicit things will be added a
+ -- second time here. This doesn't matter as the definitions are
+ -- the same.
; let { implicit_things = concatMap implicitTyThings alg_tyclss }
- ; traceTc ((text "Adding" <+> ppr alg_tyclss) $$ (text "and" <+> ppr implicit_things))
+ ; traceTc ((text "Adding" <+> ppr alg_tyclss)
+ $$ (text "and" <+> ppr implicit_things))
; tcExtendGlobalEnv implicit_things getGblEnv
}}
+ where
+ -- Pull associated types out of class declarations, to tie them into the
+ -- knot above.
+ -- NB: We put them in the same place in the list as `tcTyClDecl' will
+ -- eventually put the matching `TyThing's. That's crucial; otherwise,
+ -- the two argument lists of `mkGlobalThings' don't match up.
+ addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
+ addATs decl = [decl]
mkGlobalThings :: [LTyClDecl Name] -- The decls
-> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
%************************************************************************
%* *
+\subsection{Type checking instances of indexed types}
+%* *
+%************************************************************************
+
+Instances of indexed types are somewhat of a hybrid. They are processed
+together with class instance heads, but can contain data constructors and hence
+they share a lot of kinding and type checking code with ordinary algebraic
+data types (and GADTs).
+
+\begin{code}
+tcIdxTyInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
+tcIdxTyInstDecl (L loc decl)
+ = -- Prime error recovery, set source location
+ recoverM (returnM Nothing) $
+ setSrcSpan loc $
+ tcAddDeclCtxt decl $
+ do { -- indexed data types require -findexed-types and can't be in an
+ -- hs-boot file
+ ; gla_exts <- doptM Opt_IndexedTypes
+ ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
+ ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
+ ; checkTc (not is_boot) $ badBootTyIdxDeclErr
+
+ -- perform kind and type checking
+ ; tcIdxTyInstDecl1 decl
+ }
+
+tcIdxTyInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
+
+tcIdxTyInstDecl1 (decl@TySynonym {})
+ = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
+ do { -- check that the family declaration is for a synonym
+ unless (isSynTyCon family) $
+ addErr (wrongKindOfFamily family)
+
+ ; -- (1) kind check the right hand side of the type equation
+ ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
+
+ -- (2) type check type equation
+ ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
+ ; t_typats <- mappM tcHsKindedType k_typats
+ ; t_rhs <- tcHsKindedType k_rhs
+
+ -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
+ ; return Nothing -- !!!TODO: need TyThing for indexed synonym
+ }}
+
+tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
+ tcdCons = cons})
+ = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
+ do { -- check that the family declaration is for the right kind
+ unless (new_or_data == NewType && isNewTyCon family ||
+ new_or_data == DataType && isDataTyCon family) $
+ addErr (wrongKindOfFamily family)
+
+ ; -- (1) kind check the data declaration as usual
+ ; k_decl <- kcDataDecl decl k_tvs
+ ; let k_ctxt = tcdCtxt k_decl
+ k_cons = tcdCons k_decl
+
+ -- result kind must be '*' (otherwise, we have too few patterns)
+ ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
+
+ -- (2) type check indexed data type declaration
+ ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
+ ; unbox_strict <- doptM Opt_UnboxStrictFields
+
+ -- Check that we don't use GADT syntax for indexed types
+ ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
+
+ -- Check that a newtype has exactly one constructor
+ ; checkTc (new_or_data == DataType || isSingleton k_cons) $
+ newtypeConError tc_name (length k_cons)
+
+ ; t_typats <- mappM tcHsKindedType k_typats
+ ; stupid_theta <- tcHsKindedContext k_ctxt
+
+ ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
+ ; tycon <- fixM (\ tycon -> do
+ { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
+ tycon t_tvs))
+ k_cons
+ ; tc_rhs <-
+ case new_or_data of
+ DataType -> return (mkDataTyConRhs data_cons)
+ NewType -> ASSERT( isSingleton data_cons )
+ mkNewTyConRhs tc_name tycon (head data_cons)
+ ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
+ False h98_syntax (Just (family, t_typats))
+ -- We always assume that indexed types are recursive. Why?
+ -- (1) Due to their open nature, we can never be sure that a
+ -- further instance might not introduce a new recursive
+ -- dependency. (2) They are always valid loop breakers as
+ -- they involve a coercion.
+ })
+
+ -- construct result
+ ; return $ Just (ATyCon tycon)
+ }}
+ where
+ h98_syntax = case cons of -- All constructors have same shape
+ L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
+ other -> True
+
+-- Kind checking of indexed types
+-- -
+
+-- Kind check type patterns and kind annotate the embedded type variables.
+--
+-- * Here we check that a type instance matches its kind signature, but we do
+-- not check whether there is a pattern for each type index; the latter
+-- check is only required for type functions.
+--
+kcIdxTyPats :: TyClDecl Name
+ -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
+ -- ^^kinded tvs ^^kinded ty pats ^^res kind
+ -> TcM a
+kcIdxTyPats decl thing_inside
+ = kcHsTyVars (tcdTyVars decl) $ \tvs ->
+ do { family <- tcLookupLocatedTyCon (tcdLName decl)
+ ; let { (kinds, resKind) = splitKindFunTys (tyConKind family)
+ ; hs_typats = fromJust $ tcdTyPats decl }
+
+ -- we may not have more parameters than the kind indicates
+ ; checkTc (length kinds >= length hs_typats) $
+ tooManyParmsErr (tcdLName decl)
+
+ -- type functions can have a higher-kinded result
+ ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
+ ; typats <- zipWithM kcCheckHsType hs_typats kinds
+ ; thing_inside tvs typats resultKind family
+ }
+ where
+\end{code}
+
+
+%************************************************************************
+%* *
Kind checking
%* *
%************************************************************************
use them, whereas for the mutually recursive data types D we bring into
scope kind bindings D -> k, where k is a kind variable, and do inference.
+Indexed Types
+~~~~~~~~~~~~~
+This treatment of type synonyms only applies to Haskell 98-style synonyms.
+General type functions can be recursive, and hence, appear in `alg_decls'.
+
+The kind of an indexed type is solely determinded by its kind signature;
+hence, only kind signatures participate in the construction of the initial
+kind environment (as constructed by `getInitialKind'). In fact, we ignore
+instances of indexed types altogether in the following. However, we need to
+include the kind signatures of associated types into the construction of the
+initial kind environment. (This is handled by `allDecls').
+
\begin{code}
kcTyClDecls syn_decls alg_decls
- = do { -- First extend the kind env with each data
- -- type and class, mapping them to a type variable
- alg_kinds <- mappM getInitialKind alg_decls
+ = do { -- First extend the kind env with each data type, class, and
+ -- indexed type, mapping them to a type variable
+ let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
+ ; alg_kinds <- mappM getInitialKind initialKindDecls
; tcExtendKindEnv alg_kinds $ do
-- Now kind-check the type synonyms, in dependency order
{ (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
; tcExtendKindEnv syn_kinds $ do
- -- Now kind-check the data type and class declarations,
- -- returning kind-annotated decls
- { kc_alg_decls <- mappM (wrapLocM kcTyClDecl) alg_decls
+ -- Now kind-check the data type, class, and kind signatures,
+ -- returning kind-annotated decls; we don't kind-check
+ -- instances of indexed types yet, but leave this to
+ -- `tcInstDecls1'
+ { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
+ (filter (not . isIdxTyDecl . unLoc) alg_decls)
; return (kc_syn_decls, kc_alg_decls) }}}
+ where
+ -- get all declarations relevant for determining the initial kind
+ -- environment
+ allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
+ | L _ at <- ats
+ , isKindSigDecl at]
+ allDecls decl | isIdxTyDecl decl = []
+ | otherwise = [decl]
------------------------------------------------------------------------
-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,
+getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
+-- Only for data type, class, and indexed type declarations
+-- Get as much info as possible from the data, class, or indexed type decl,
-- so as to maximise usefulness of error messages
-getInitialKind (L _ decl)
+getInitialKind 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) }
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
+ mk_res_kind (TyFunction { tcdKind = kind }) = return kind
+ mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
+ -- On GADT-style and data signature declarations we allow a kind
+ -- signature
-- data T :: *->* where { ... }
mk_res_kind other = return liftedTypeKind
kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
-- Not used for type synonyms (see kcSynDecl)
-kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
- = kcTyClDeclBody decl $ \ tvs' ->
- do { ctxt' <- kcHsContext ctxt
- ; cons' <- mappM (wrapLocM kc_con_decl) cons
- ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) }
- where
- 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 -> do { ty' <- kcHsSigType ty; return (ResTyGADT 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') }
- kc_con_details (InfixCon bty1 bty2)
- = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
- kc_con_details (RecCon fields)
- = do { fields' <- mappM kc_field fields; return (RecCon fields') }
-
- kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
+kcTyClDecl decl@(TyData {})
+ = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
+ kcTyClDeclBody decl $
+ kcDataDecl decl
- kc_larg_ty bty = case new_or_data of
- DataType -> kcHsSigType bty
- NewType -> kcHsLiftedSigType bty
- -- Can't allow an unlifted type for newtypes, because we're effectively
- -- going to remove the constructor while coercing it to a lifted type.
- -- And newtypes can't be bang'd
+kcTyClDecl decl@(TyFunction {})
+ = kcTyClDeclBody decl $ \ tvs' ->
+ return (decl {tcdTyVars = tvs'})
-kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs})
+kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
= kcTyClDeclBody decl $ \ tvs' ->
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'}) }
+ ; ats' <- mappM (wrapLocM kcTyClDecl) ats
+ ; sigs' <- mappM (wrapLocM kc_sig ) sigs
+ ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
+ tcdATs = ats'}) }
where
kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
; return (TypeSig nm op_ty') }
-- 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
+-- check the result kind matches
kcTyClDeclBody decl thing_inside
= tcAddDeclCtxt decl $
do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
[ L loc (KindedTyVar (hsTyVarName tv) k)
| (L loc tv, k) <- zip hs_tvs kinds]
; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
+
+-- Kind check a data declaration, assuming that we already extended the
+-- kind environment with the type variables of the left-hand side (these
+-- kinded type variables are also passed as the second parameter).
+--
+kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
+kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
+ tvs
+ = do { ctxt' <- kcHsContext ctxt
+ ; cons' <- mappM (wrapLocM kc_con_decl) cons
+ ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
+ where
+ 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 -> do { ty' <- kcHsSigType ty; return (ResTyGADT 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') }
+ kc_con_details (InfixCon bty1 bty2)
+ = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
+ kc_con_details (RecCon fields)
+ = do { fields' <- mappM kc_field fields; return (RecCon fields') }
+
+ kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
+
+ kc_larg_ty bty = case new_or_data of
+ DataType -> kcHsSigType bty
+ NewType -> kcHsLiftedSigType bty
+ -- Can't allow an unlifted type for newtypes, because we're effectively
+ -- going to remove the constructor while coercing it to a lifted type.
+ -- And newtypes can't be bang'd
\end{code}
%************************************************************************
\begin{code}
-tcSynDecls :: (Name -> ArgVrcs) -> [LTyClDecl Name] -> TcM [TyThing]
-tcSynDecls calc_vrcs [] = return []
-tcSynDecls calc_vrcs (decl : decls)
- = do { syn_tc <- addLocM (tcSynDecl calc_vrcs) decl
- ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls calc_vrcs decls)
+tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
+tcSynDecls [] = return []
+tcSynDecls (decl : decls)
+ = do { syn_tc <- addLocM tcSynDecl decl
+ ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
; return (syn_tc : syn_tcs) }
-tcSynDecl calc_vrcs
+tcSynDecl
(TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
= tcTyVarBndrs tvs $ \ tvs' -> do
{ traceTc (text "tcd1" <+> ppr tc_name)
; rhs_ty' <- tcHsKindedType rhs_ty
- ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty' (calc_vrcs tc_name))) }
+ ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
--------------------
-tcTyClDecl :: (Name -> ArgVrcs) -> (Name -> RecFlag)
- -> TyClDecl Name -> TcM TyThing
+tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
+
+tcTyClDecl calc_isrec decl
+ = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
-tcTyClDecl calc_vrcs calc_isrec decl
- = tcAddDeclCtxt decl (tcTyClDecl1 calc_vrcs calc_isrec decl)
+ -- kind signature for a type function
+tcTyClDecl1 _calc_isrec
+ (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { traceTc (text "type family: " <+> ppr tc_name)
+ ; gla_exts <- doptM Opt_IndexedTypes
+
+ -- Check that we don't use kind signatures without Glasgow extensions
+ ; checkTc gla_exts $ badSigTyDecl tc_name
+
+ ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
+ }
-tcTyClDecl1 calc_vrcs calc_isrec
+ -- kind signature for an indexed data type
+tcTyClDecl1 _calc_isrec
+ (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
+ tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { traceTc (text "data/newtype family: " <+> ppr tc_name)
+ ; extra_tvs <- tcDataKindSig (Just ksig)
+ ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
+
+ ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
+ ; gla_exts <- doptM Opt_IndexedTypes
+
+ -- Check that we don't use kind signatures without Glasgow extensions
+ ; checkTc gla_exts $ badSigTyDecl tc_name
+
+ ; tycon <- buildAlgTyCon tc_name final_tvs []
+ (case new_or_data of
+ DataType -> OpenDataTyCon
+ NewType -> OpenNewTyCon)
+ Recursive False True Nothing
+ ; return [ATyCon tycon]
+ }
+
+tcTyClDecl1 calc_isrec
(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
= tcTyVarBndrs tvs $ \ tvs' -> do
-- Check that we don't use GADT syntax in H98 world
; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
+ -- Check that we don't use kind signatures without Glasgow extensions
+ ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
+
+ -- Check that the stupid theta is empty for a GADT-style declaration
+ ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
+
-- Check that there's at least one condecl,
- -- or else we're reading an interface file, or -fglasgow-exts
+ -- or else we're reading an hs-boot file, or -fglasgow-exts
; checkTc (not (null cons) || gla_exts || is_boot)
(emptyConDeclsErr tc_name)
{ data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
tycon final_tvs))
cons
- ; let tc_rhs
- | null cons && is_boot -- In a hs-boot file, empty cons means
- = AbstractTyCon -- "don't know"; hence Abstract
- | otherwise
- = case new_or_data of
- DataType -> mkDataTyConRhs data_cons
- NewType -> ASSERT( isSingleton data_cons )
- mkNewTyConRhs tycon (head data_cons)
- ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs arg_vrcs is_rec
- (want_generic && canDoGenerics data_cons)
+ ; tc_rhs <-
+ if null cons && is_boot -- In a hs-boot file, empty cons means
+ then return AbstractTyCon -- "don't know"; hence Abstract
+ else case new_or_data of
+ DataType -> return (mkDataTyConRhs data_cons)
+ NewType ->
+ ASSERT( isSingleton data_cons )
+ mkNewTyConRhs tc_name tycon (head data_cons)
+ ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
+ (want_generic && canDoGenerics data_cons) h98_syntax Nothing
})
- ; return (ATyCon tycon)
+ ; return [ATyCon tycon]
}
where
- arg_vrcs = calc_vrcs tc_name
is_rec = calc_isrec tc_name
h98_syntax = case cons of -- All constructors have same shape
L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
other -> True
-tcTyClDecl1 calc_vrcs calc_isrec
+tcTyClDecl1 calc_isrec
(ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
tcdCtxt = ctxt, tcdMeths = meths,
- tcdFDs = fundeps, tcdSigs = sigs} )
+ tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
= tcTyVarBndrs tvs $ \ tvs' -> do
{ ctxt' <- tcHsKindedContext ctxt
; fds' <- mappM (addLocM tc_fundep) fundeps
+ ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
+ ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
; sig_stuff <- tcClassSigs class_name sigs meths
; clas <- fixM (\ clas ->
let -- This little knot is just so we can get
-- hold of the name of the class TyCon, which we
- -- need to look up its recursiveness and variance
+ -- need to look up its recursiveness
tycon_name = tyConName (classTyCon clas)
tc_isrec = calc_isrec tycon_name
- tc_vrcs = calc_vrcs tycon_name
in
- buildClass class_name tvs' ctxt' fds'
- sig_stuff tc_isrec tc_vrcs)
- ; return (AClass clas) }
+ buildClass class_name tvs' ctxt' fds' ats'
+ sig_stuff tc_isrec)
+ ; return (AClass clas : ats')
+ -- NB: Order is important due to the call to `mkGlobalThings' when
+ -- tying the the type and class declaration type checking knot.
+ }
where
tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
; tvs2' <- mappM tcLookupTyVar tvs2 ;
; return (tvs1', tvs2') }
-
-tcTyClDecl1 calc_vrcs calc_isrec
+ -- For each AT argument compute the position of the corresponding class
+ -- parameter in the class head. This will later serve as a permutation
+ -- vector when checking the validity of instance declarations.
+ setTyThingPoss [ATyCon tycon] atTyVars =
+ let classTyVars = hsLTyVarNames tvs
+ poss = catMaybes
+ . map (`elemIndex` classTyVars)
+ . hsLTyVarNames
+ $ atTyVars
+ -- There will be no Nothing, as we already passed renaming
+ in
+ ATyCon (setTyConArgPoss tycon poss)
+ setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
+
+tcTyClDecl1 calc_isrec
(ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
- = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0 []))
+ = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
-----------------------------------
tcConDecl :: Bool -- True <=> -funbox-strict_fields
- -> NewOrData -> TyCon -> [TyVar]
- -> ConDecl Name -> TcM DataCon
+ -> NewOrData
+ -> TyCon -> [TyVar]
+ -> ConDecl Name
+ -> TcM DataCon
tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
(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]
+ [NotMarkedStrict]
(map unLoc field_lbls)
- tc_tvs [] [arg_ty']
- tycon (mkTyVarTys tc_tvs) }
+ tc_tvs [] -- No existentials
+ [] [] -- No equalities, predicates
+ [arg_ty']
+ tycon }
-- 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
+ PrefixCon [arg_ty] -> tc_datacon [] arg_ty
RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
- other -> failWithTc (newtypeFieldErr name (length (hsConArgs details)))
+ other ->
+ failWithTc (newtypeFieldErr name (length (hsConArgs details)))
-- Check that the constructor has exactly one field
}
(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
+ ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
; let
- 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
; arg_tys <- mappM tcHsBangType btys
- ; buildDataCon (unLoc name) is_infix is_vanilla
+ ; buildDataCon (unLoc name) is_infix
(argStrictness unbox_strict tycon bangs arg_tys)
(map unLoc field_lbls)
- 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.
+ univ_tvs ex_tvs eq_preds ctxt' arg_tys
+ data_tc }
+ -- 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
}
-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
-
+tcResultType :: TyCon
+ -> [TyVar] -- data T a b c = ...
+ -> [TyVar] -- where MkT :: forall a b c. ...
+ -> ResType Name
+ -> TcM ([TyVar], -- Universal
+ [TyVar], -- Existential
+ [(TyVar,Type)], -- Equality predicates
+ TyCon) -- TyCon given in the ResTy
+ -- We don't check that the TyCon given in the ResTy is
+ -- the same as the parent tycon, becuase we are in the middle
+ -- of a recursive knot; so it's postponed until checkValidDataCon
+
+tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
+ = return (tc_tvs, dc_tvs, [], decl_tycon)
+ -- In H98 syntax the dc_tvs are the existential ones
+ -- data T a b c = forall d e. MkT ...
+ -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
+
+tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
+ -- E.g. data T a b c where
+ -- MkT :: forall x y z. T (x,y) z z
+ -- Then we generate
+ -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
+
+ = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
+ -- NB: tc_tvs and dc_tvs are distinct
+ ; let univ_tvs = choose_univs [] tc_tvs res_tys
+ -- Each univ_tv is either a dc_tv or a tc_tv
+ ex_tvs = dc_tvs `minusList` univ_tvs
+ eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
+ tv `elem` tc_tvs]
+ ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
+ where
+ -- choose_univs uses the res_ty itself if it's a type variable
+ -- and hasn't already been used; otherwise it uses one of the tc_tvs
+ choose_univs used tc_tvs []
+ = ASSERT( null tc_tvs ) []
+ choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
+ | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
+ = tv : choose_univs (tv:used) tc_tvs res_tys
+ | otherwise
+ = tc_tv : choose_univs used tc_tvs res_tys
-------------------
argStrictness :: Bool -- True <=> -funbox-strict_fields
-- We attempt to unbox/unpack a strict field when either:
-- (i) The field is marked '!!', or
-- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
-
+--
+-- We have turned off unboxing of newtypes because coercions make unboxing
+-- and reboxing more complicated
chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
= case bang of
HsNoBang -> NotMarkedStrict
- HsStrict | unbox_strict_fields && can_unbox -> MarkedUnboxed
- HsUnbox | can_unbox -> MarkedUnboxed
+ HsStrict | unbox_strict_fields
+ && can_unbox arg_ty -> MarkedUnboxed
+ HsUnbox | can_unbox arg_ty -> MarkedUnboxed
other -> MarkedStrict
where
- can_unbox = case splitTyConApp_maybe arg_ty of
- Nothing -> False
- Just (arg_tycon, _) -> not (isRecursiveTyCon tycon) &&
- isProductTyCon arg_tycon
+ -- we can unbox if the type is a chain of newtypes with a product tycon
+ -- at the end
+ can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
+ Nothing -> False
+ Just (arg_tycon, tycon_args) ->
+ not (isRecursiveTyCon tycon) &&
+ isProductTyCon arg_tycon &&
+ (if isNewTyCon arg_tycon then
+ can_unbox (newTyConInstRhs arg_tycon tycon_args)
+ else True)
\end{code}
%************************************************************************
-- of the constructor.
checkValidTyCon :: TyCon -> TcM ()
-checkValidTyCon tc
+checkValidTyCon tc
| isSynTyCon tc
- = checkValidType syn_ctxt syn_rhs
+ = case synTyConRhs tc of
+ OpenSynTyCon _ -> return ()
+ SynonymTyCon ty -> checkValidType syn_ctxt ty
| otherwise
= -- Check the context on the data decl
checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
where
syn_ctxt = TySynCtxt name
name = tyConName tc
- syn_rhs = synTyConRhs tc
data_cons = tyConDataCons tc
groups = equivClasses cmp_fld (concatMap get_fields data_cons)
get_fields con = dataConFieldLabels con `zip` repeat con
-- dataConFieldLabels may return the empty list, which is fine
- -- 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)
+ -- See Note [GADT record selectors] in MkId.lhs
+ -- We must check (a) that the named field has the same
+ -- type in each constructor
+ -- (b) that those constructors have the same result type
+ --
+ -- However, the constructors may have differently named type variable
+ -- and (worse) we don't know how the correspond to each other. E.g.
+ -- C1 :: forall a b. { f :: a, g :: b } -> T a b
+ -- C2 :: forall d c. { f :: c, g :: c } -> T c d
+ --
+ -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
+ -- result type against other candidates' types BOTH WAYS ROUND.
+ -- If they magically agrees, take the substitution and
+ -- apply them to the latter ones, and see if they match perfectly.
check_fields fields@((label, con1) : other_fields)
-- These fields all have the same name, but are from
-- different constructors in the data type
-- NB: this check assumes that all the constructors of a given
-- data type use the same type variables
where
- tvs1 = mkVarSet (dataConTyVars con1)
+ tvs1 = mkVarSet (dataConAllTyVars con1)
res1 = dataConResTys con1
fty1 = dataConFieldType con1 label
= do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
where
- tvs2 = mkVarSet (dataConTyVars con2)
+ tvs2 = mkVarSet (dataConAllTyVars con2)
res2 = dataConResTys con2
fty2 = dataConFieldType con2 label
= setSrcSpan (srcLocSpan (getSrcLoc con)) $
addErrCtxt (dataConCtxt con) $
do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
- ; checkValidType ctxt (idType (dataConWrapId con)) }
-
- -- This checks the argument types and
- -- ambiguity of the existential context (if any)
- --
- -- Note [Sept 04] Now that tvs is all the tvs, this
- -- test doesn't actually check anything
--- ; checkFreeness tvs ex_theta }
+ ; checkValidType ctxt (dataConUserType con) }
where
ctxt = ConArgCtxt (dataConName con)
--- (tvs, ex_theta, _, _, _) = dataConSig con
-
-------------------------------
checkValidClass :: Class -> TcM ()
= vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
, nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
+badStupidTheta tc_name
+ = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
+
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 ]
= 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]
+badSigTyDecl tc_name
+ = vcat [ ptext SLIT("Illegal kind signature") <+>
+ quotes (ppr tc_name)
+ , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
+
+badKindSigCtxt tc_name
+ = vcat [ ptext SLIT("Illegal context in kind signature") <+>
+ quotes (ppr tc_name)
+ , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
+
+badIdxTyDecl tc_name
+ = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
+ quotes (ppr tc_name)
+ , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
+
+badGadtIdxTyDecl tc_name
+ = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
+ quotes (ppr tc_name)
+ , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
+
+tooManyParmsErr tc_name
+ = ptext SLIT("Indexed type instance has too many parameters:") <+>
+ quotes (ppr tc_name)
+
+tooFewParmsErr tc_name
+ = ptext SLIT("Indexed type instance has too few parameters:") <+>
+ quotes (ppr tc_name)
+
+badBootTyIdxDeclErr =
+ ptext SLIT("Illegal indexed type instance in hs-boot file")
+
+wrongKindOfFamily family =
+ ptext SLIT("Wrong category of type instance; declaration was for a") <+>
+ kindOfFamily
+ where
+ kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
+ | isDataTyCon family = ptext SLIT("data type")
+ | isNewTyCon family = ptext SLIT("newtype")
+
emptyConDeclsErr tycon
= sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
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