%
+% (c) The University of Glasgow 2006
% (c) The AQUA Project, Glasgow University, 1996-1998
%
-\section[TcTyClsDecls]{Typecheck type and class declarations}
+
+TcTyClsDecls: Typecheck type and class declarations
\begin{code}
+{-# OPTIONS_GHC -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings
+-- for details
+
module TcTyClsDecls (
- tcTyAndClassDecls, tcIdxTyInstDecl
+ tcTyAndClassDecls, tcFamInstDecl
) where
#include "HsVersions.h"
-import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
- ConDecl(..), Sig(..), NewOrData(..), ResType(..),
- tyClDeclTyVars, isSynDecl, isClassDecl, isIdxTyDecl,
- isKindSigDecl, hsConArgs, LTyClDecl, tcdName,
- hsTyVarName, LHsTyVarBndr, LHsType, HsType(..),
- mkHsAppTy
- )
-import HsTypes ( HsBang(..), getBangStrictness )
-import BasicTypes ( RecFlag(..), StrictnessMark(..) )
-import HscTypes ( implicitTyThings, ModDetails )
-import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
- mkDataTyConRhs, mkNewTyConRhs )
+import HsSyn
+import HsTypes
+import BasicTypes
+import HscTypes
+import BuildTyCl
+import TcUnify
import TcRnMonad
-import TcEnv ( TyThing(..),
- tcLookupLocated, tcLookupLocatedGlobal,
- tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
- tcExtendRecEnv, tcLookupTyVar, InstInfo )
-import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
-import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
-import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
- kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
- kcHsSigType, tcHsBangType, tcLHsConResTy,
- tcDataKindSig, kcCheckHsType )
-import TcMType ( newKindVar, checkValidTheta, checkValidType,
- -- checkFreeness,
- UserTypeCtxt(..), SourceTyCtxt(..) )
-import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
- mkArrowKind, liftedTypeKind, mkTyVarTys,
- tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
-import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy,
- newTyConInstRhs, isLiftedTypeKind, Kind
- -- pprParendType, pprThetaArrow
- )
-import Generics ( validGenericMethodType, canDoGenerics )
-import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
-import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
- OpenNewTyCon ),
- SynTyConRhs( OpenSynTyCon, SynonymTyCon ),
- tyConDataCons, mkForeignTyCon, isProductTyCon,
- isRecursiveTyCon, isOpenTyCon,
- tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
- isNewTyCon, tyConKind, makeTyConAssoc, isAssocTyCon )
-import DataCon ( DataCon, dataConUserType, dataConName,
- dataConFieldLabels, dataConTyCon, dataConAllTyVars,
- dataConFieldType, dataConResTys )
-import Var ( TyVar, idType, idName )
-import VarSet ( elemVarSet, mkVarSet )
-import Name ( Name, getSrcLoc )
+import TcEnv
+import TcTyDecls
+import TcClassDcl
+import TcHsType
+import TcMType
+import TcType
+import FunDeps
+import Type
+import Generics
+import Class
+import TyCon
+import DataCon
+import Var
+import VarSet
+import Name
+import OccName
import Outputable
-import Maybe ( isJust, fromJust, isNothing )
-import Maybes ( expectJust )
-import Unify ( tcMatchTys, tcMatchTyX )
-import Util ( zipLazy, isSingleton, notNull, sortLe )
-import List ( partition )
-import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
-import ListSetOps ( equivClasses, minusList )
-import List ( delete )
-import Digraph ( SCC(..) )
-import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
- Opt_UnboxStrictFields ) )
+import Maybes
+import Monad
+import Unify
+import Util
+import SrcLoc
+import ListSetOps
+import Digraph
+import DynFlags
+
+import Data.List
+import Control.Monad ( mplus )
\end{code}
-> TcM TcGblEnv -- Input env extended by types and classes
-- and their implicit Ids,DataCons
tcTyAndClassDecls boot_details allDecls
- = do { -- Omit instances of indexed types; they are handled together
+ = do { -- Omit instances of type families; they are handled together
-- with the *heads* of class instances
- ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
+ ; let decls = filter (not . isFamInstDecl . unLoc) allDecls
-- First check for cyclic type synonysm or classes
-- See notes with checkCycleErrs
; let { -- Calculate rec-flag
; calc_rec = calcRecFlags boot_details rec_alg_tyclss
; tc_decl = addLocM (tcTyClDecl calc_rec) }
+
-- Type-check the type synonyms, and extend the envt
; syn_tycons <- tcSynDecls kc_syn_decls
; tcExtendGlobalEnv syn_tycons $ do
-- 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))
; 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]
%************************************************************************
%* *
-\subsection{Type checking instances of indexed types}
+\subsection{Type checking family instances}
%* *
%************************************************************************
-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).
+Family instances 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 InstInfo, Maybe TyThing) -- Nothing if error
-tcIdxTyInstDecl (L loc decl)
+tcFamInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
+tcFamInstDecl (L loc decl)
= -- Prime error recovery, set source location
- recoverM (returnM (Nothing, Nothing)) $
+ recoverM (returnM Nothing) $
setSrcSpan loc $
tcAddDeclCtxt decl $
- do { -- indexed data types require -fglasgow-exts and can't be in an
+ do { -- type families require -ftype-families and can't be in an
-- hs-boot file
- ; gla_exts <- doptM Opt_GlasgowExts
+ ; type_families <- doptM Opt_TypeFamilies
; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
- ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
- ; checkTc (not is_boot) $ badBootTyIdxDeclErr
+ ; checkTc type_families $ badFamInstDecl (tcdLName decl)
+ ; checkTc (not is_boot) $ badBootFamInstDeclErr
-- perform kind and type checking
- ; tcIdxTyInstDecl1 decl
+ ; tcFamInstDecl1 decl
}
-tcIdxTyInstDecl1 :: TyClDecl Name
- -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
+tcFamInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
-tcIdxTyInstDecl1 (decl@TySynonym {})
- = kcIdxTyPats decl $ \k_tvs k_typats resKind _ ->
- do { -- (1) kind check the right hand side of the type equation
+ -- "type instance"
+tcFamInstDecl1 (decl@TySynonym {tcdLName = L loc tc_name})
+ = 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
+ -- we need the exact same number of type parameters as the family
+ -- declaration
+ ; let famArity = tyConArity family
+ ; checkTc (length k_typats == famArity) $
+ wrongNumberOfParmsErr famArity
+
-- (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
- -- construct type rewrite rule
- -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
- ; return (Nothing, Nothing) -- !!!TODO: need InstInfo for eq axioms
+ -- (3) check that
+ -- - check the well-formedness of the instance
+ ; checkValidTypeInst t_typats t_rhs
+
+ -- (4) construct representation tycon
+ ; rep_tc_name <- newFamInstTyConName tc_name loc
+ ; tycon <- buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs)
+ (Just (family, t_typats))
+
+ ; return $ Just (ATyCon tycon)
}}
-
-tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
- tcdCons = cons})
+
+ -- "newtype instance" and "data instance"
+tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
+ tcdCons = cons})
= kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
- do { -- (1) kind check the data declaration as usual
+ do { -- check that the family declaration is for the right kind
+ unless (isAlgTyCon 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
+ ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr (tyConArity family)
-- (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
+ -- kind check the type indexes and the context
+ ; t_typats <- mappM tcHsKindedType k_typats
+ ; stupid_theta <- tcHsKindedContext k_ctxt
+
+ -- (3) Check that
+ -- - left-hand side contains no type family applications
+ -- (vanilla synonyms are fine, though, and we checked for
+ -- foralls earlier)
+ ; mappM_ checkTyFamFreeness t_typats
+
+ -- - we don't use GADT syntax for indexed types
; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
- -- Check that a newtype has exactly one constructor
+ -- - 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
-
+ -- (4) construct representation tycon
+ ; rep_tc_name <- newFamInstTyConName tc_name loc
; tycon <- fixM (\ tycon -> do
- { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
- tycon t_tvs))
+ { data_cons <- mappM (addLocM (tcConDecl unbox_strict 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 tc_name t_tvs stupid_theta tc_rhs Recursive
+ NewType -> ASSERT( not (null data_cons) )
+ mkNewTyConRhs rep_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
})
-- construct result
- ; return (Nothing, Just (ATyCon tycon))
+ ; return $ Just (ATyCon tycon)
}}
where
h98_syntax = case cons of -- All constructors have same shape
--
-- * 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.
+-- check is only required for type synonym instances.
--
kcIdxTyPats :: TyClDecl Name
-> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
-> TcM a
kcIdxTyPats decl thing_inside
= kcHsTyVars (tcdTyVars decl) $ \tvs ->
- do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
- ; let { family = case tc_ty_thing of
- AGlobal (ATyCon family) -> family
- ; (kinds, resKind) = splitKindFunTys (tyConKind family)
+ 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
-- type functions can have a higher-kinded result
; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
- ; typats <- zipWithM kcCheckHsType hs_typats kinds
+ ; typats <- TcRnMonad.zipWithM kcCheckHsType hs_typats kinds
; thing_inside tvs typats resultKind family
}
where
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
+Type families
~~~~~~~~~~~~~
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;
+The kind of a type family 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
+instances of families altogether in the following. However, we need to
+include the kinds of associated families into the construction of the
initial kind environment. (This is handled by `allDecls').
\begin{code}
-- instances of indexed types yet, but leave this to
-- `tcInstDecls1'
{ kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
- (filter (not . isIdxTyDecl . unLoc) alg_decls)
+ (filter (not . isFamInstDecl . unLoc) alg_decls)
; return (kc_syn_decls, kc_alg_decls) }}}
where
-- environment
allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
| L _ at <- ats
- , isKindSigDecl at]
- allDecls decl | isIdxTyDecl decl = []
- | otherwise = [decl]
+ , isFamilyDecl at]
+ allDecls decl | isFamInstDecl decl = []
+ | otherwise = [decl]
------------------------------------------------------------------------
getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
mk_arg_kind (UserTyVar _) = newKindVar
mk_arg_kind (KindedTyVar _ kind) = return kind
- 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
+ mk_res_kind (TyFamily { tcdKind = Just 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
-- Not used for type synonyms (see kcSynDecl)
kcTyClDecl decl@(TyData {})
- = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
+ = ASSERT( not . isFamInstDecl $ decl ) -- must not be a family instance
kcTyClDeclBody decl $
kcDataDecl decl
-kcTyClDecl decl@(TyFunction {})
- = kcTyClDeclBody decl $ \ tvs' ->
- return (decl {tcdTyVars = tvs'})
+kcTyClDecl decl@(TyFamily {})
+ = kcFamilyDecl [] decl -- the empty list signals a toplevel decl
kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
= kcTyClDeclBody decl $ \ tvs' ->
do { is_boot <- tcIsHsBoot
; ctxt' <- kcHsContext ctxt
- ; ats' <- mappM (wrapLocM kcTyClDecl) ats
- ; sigs' <- mappM (wrapLocM kc_sig ) sigs
+ ; ats' <- mappM (wrapLocM (kcFamilyDecl tvs')) ats
+ ; sigs' <- mappM (wrapLocM kc_sig) sigs
; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
tcdATs = ats'}) }
where
; 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
+ -- doc comments are typechecked to Nothing here
+ 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')
+ return (ConDecl name expl ex_tvs' ex_ctxt' details' res' Nothing)
kc_con_details (PrefixCon btys)
- = do { btys' <- mappM kc_larg_ty btys ; return (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') }
+ = 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') }
+ = do { fields' <- mappM kc_field fields
+ ; return (RecCon fields') }
- kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
+ kc_field (ConDeclField fld bty d) = do { bty' <- kc_larg_ty bty
+ ; return (ConDeclField fld bty' d) }
kc_larg_ty bty = case new_or_data of
DataType -> kcHsSigType 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
+
+-- Kind check a family declaration or type family default declaration.
+--
+kcFamilyDecl :: [LHsTyVarBndr Name] -- tyvars of enclosing class decl if any
+ -> TyClDecl Name -> TcM (TyClDecl Name)
+kcFamilyDecl classTvs decl@(TyFamily {tcdKind = kind})
+ = kcTyClDeclBody decl $ \tvs' ->
+ do { mapM_ unifyClassParmKinds tvs'
+ ; return (decl {tcdTyVars = tvs',
+ tcdKind = kind `mplus` Just liftedTypeKind})
+ -- default result kind is '*'
+ }
+ where
+ unifyClassParmKinds (L _ (KindedTyVar n k))
+ | Just classParmKind <- lookup n classTyKinds = unifyKind k classParmKind
+ | otherwise = return ()
+ classTyKinds = [(n, k) | L _ (KindedTyVar n k) <- classTvs]
+kcFamilyDecl _ decl@(TySynonym {}) -- type family defaults
+ = panic "TcTyClsDecls.kcFamilyDecl: not implemented yet"
\end{code}
; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
; return (syn_tc : syn_tcs) }
+ -- "type"
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' (SynonymTyCon rhs_ty'))) }
+ ; tycon <- buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty') Nothing
+ ; return (ATyCon tycon)
+ }
--------------------
tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
tcTyClDecl calc_isrec decl
= tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
- -- kind signature for a type function
+ -- "type family" declarations
tcTyClDecl1 _calc_isrec
- (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
+ (TyFamily {tcdFlavour = TypeFamily,
+ tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = Just kind})
+ -- NB: kind at latest
+ -- added during
+ -- kind checking
= tcTyVarBndrs tvs $ \ tvs' -> do
{ traceTc (text "type family: " <+> ppr tc_name)
- ; gla_exts <- doptM Opt_GlasgowExts
+ ; idx_tys <- doptM Opt_TypeFamilies
- -- Check that we don't use kind signatures without Glasgow extensions
- ; checkTc gla_exts $ badSigTyDecl tc_name
+ -- Check that we don't use families without -ftype-families
+ ; checkTc idx_tys $ badFamInstDecl tc_name
- ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
+ ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) Nothing
+ ; return [ATyCon tycon]
}
- -- kind signature for an indexed data type
+ -- "newtype family" or "data family" declaration
tcTyClDecl1 _calc_isrec
- (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
- tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
+ (TyFamily {tcdFlavour = DataFamily,
+ tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = mb_kind})
= tcTyVarBndrs tvs $ \ tvs' -> do
- { traceTc (text "data/newtype family: " <+> ppr tc_name)
- ; extra_tvs <- tcDataKindSig (Just ksig)
+ { traceTc (text "data family: " <+> ppr tc_name)
+ ; extra_tvs <- tcDataKindSig mb_kind
; let final_tvs = tvs' ++ extra_tvs -- we may not need these
- ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
- ; gla_exts <- doptM Opt_GlasgowExts
+ ; idx_tys <- doptM Opt_TypeFamilies
- -- Check that we don't use kind signatures without Glasgow extensions
- ; checkTc gla_exts $ badSigTyDecl tc_name
+ -- Check that we don't use families without -ftype-families
+ ; checkTc idx_tys $ badFamInstDecl tc_name
; tycon <- buildAlgTyCon tc_name final_tvs []
- (case new_or_data of
- DataType -> OpenDataTyCon
- NewType -> OpenNewTyCon)
- Recursive False True Nothing
+ mkOpenDataTyConRhs Recursive False True Nothing
; return [ATyCon tycon]
}
+ -- "newtype" and "data"
tcTyClDecl1 calc_isrec
(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
; stupid_theta <- tcHsKindedContext ctxt
; want_generic <- doptM Opt_Generics
; unbox_strict <- doptM Opt_UnboxStrictFields
- ; gla_exts <- doptM Opt_GlasgowExts
+ ; empty_data_decls <- doptM Opt_EmptyDataDecls
+ ; kind_signatures <- doptM Opt_KindSignatures
+ ; gadt_ok <- doptM Opt_GADTs
; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
-- Check that we don't use GADT syntax in H98 world
- ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
+ ; checkTc (gadt_ok || 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)
+ ; checkTc (kind_signatures || 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 hs-boot file, or -fglasgow-exts
- ; checkTc (not (null cons) || gla_exts || is_boot)
+ -- or else we're reading an hs-boot file, or -XEmptyDataDecls
+ ; checkTc (not (null cons) || empty_data_decls || is_boot)
(emptyConDeclsErr tc_name)
-- Check that a newtype has exactly one constructor
(newtypeConError tc_name (length cons))
; tycon <- fixM (\ tycon -> do
- { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
- tycon final_tvs))
+ { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon final_tvs))
cons
; tc_rhs <-
if null cons && is_boot -- In a hs-boot file, empty cons means
else case new_or_data of
DataType -> return (mkDataTyConRhs data_cons)
NewType ->
- ASSERT( isSingleton data_cons )
+ ASSERT( not (null 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
{ ctxt' <- tcHsKindedContext ctxt
; fds' <- mappM (addLocM tc_fundep) fundeps
; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
- ; let ats' = map makeTyThingAssoc . concat $ atss
+ ; 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
tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
; tvs2' <- mappM tcLookupTyVar tvs2 ;
; return (tvs1', tvs2') }
- makeTyThingAssoc (ATyCon tycon) = ATyCon (makeTyConAssoc tycon)
- makeTyThingAssoc _ = panic "makeTyThingAssoc"
+ -- 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})
-----------------------------------
tcConDecl :: Bool -- True <=> -funbox-strict_fields
- -> 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 -}
- [NotMarkedStrict]
- (map unLoc field_lbls)
- 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
- 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 -- Data types
- (ConDecl name _ tvs ctxt details res_ty)
+tcConDecl unbox_strict tycon tc_tvs -- Data types
+ (ConDecl name _ tvs ctxt details res_ty _)
= tcTyVarBndrs tvs $ \ tvs' -> do
{ ctxt' <- tcHsKindedContext ctxt
; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
; let
+ -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
tc_datacon is_infix field_lbls btys
= do { let bangs = map getBangStrictness btys
; arg_tys <- mappM tcHsBangType btys
; buildDataCon (unLoc name) is_infix
- (argStrictness unbox_strict tycon bangs arg_tys)
+ (argStrictness unbox_strict bangs arg_tys)
(map unLoc field_lbls)
univ_tvs ex_tvs eq_preds ctxt' arg_tys
data_tc }
InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
RecCon fields -> tc_datacon False field_names btys
where
- (field_names, btys) = unzip fields
-
+ field_names = map cd_fld_name fields
+ btys = map cd_fld_type fields
}
tcResultType :: TyCon
-> [TyVar] -- where MkT :: forall a b c. ...
-> ResType Name
-> TcM ([TyVar], -- Universal
- [TyVar], -- Existential
+ [TyVar], -- Existential (distinct OccNames from univs)
[(TyVar,Type)], -- Equality predicates
TyCon) -- TyCon given in the ResTy
-- We don't check that the TyCon given in the ResTy is
-- ([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
+
+ ; let univ_tvs = choose_univs [] tidy_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,
| otherwise
= tc_tv : choose_univs used tc_tvs res_tys
--------------------
+ -- NB: tc_tvs and dc_tvs are distinct, but
+ -- we want them to be *visibly* distinct, both for
+ -- interface files and general confusion. So rename
+ -- the tc_tvs, since they are not used yet (no
+ -- consequential renaming needed)
+ init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
+ (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
+ tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
+ where
+ name = tyVarName tv
+ (env', occ') = tidyOccName env (getOccName name)
+
+ -------------------
argStrictness :: Bool -- True <=> -funbox-strict_fields
- -> TyCon -> [HsBang]
+ -> [HsBang]
-> [TcType] -> [StrictnessMark]
-argStrictness unbox_strict tycon bangs arg_tys
+argStrictness unbox_strict bangs arg_tys
= ASSERT( length bangs == length arg_tys )
- zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
+ zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
-- We attempt to unbox/unpack a strict field when either:
-- (i) The field is marked '!!', or
--
-- 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
+chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
+chooseBoxingStrategy unbox_strict_fields arg_ty bang
= case bang of
HsNoBang -> NotMarkedStrict
HsStrict | unbox_strict_fields
can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
Nothing -> False
Just (arg_tycon, tycon_args) ->
- not (isRecursiveTyCon tycon) &&
+ not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
isProductTyCon arg_tycon &&
(if isNewTyCon arg_tycon then
can_unbox (newTyConInstRhs arg_tycon tycon_args)
else True)
\end{code}
+Note [Recursive unboxing]
+~~~~~~~~~~~~~~~~~~~~~~~~~
+Be careful not to try to unbox this!
+ data T = MkT !T Int
+But it's the *argument* type that matters. This is fine:
+ data S = MkS S !Int
+because Int is non-recursive.
+
%************************************************************************
%* *
\subsection{Dependency analysis}
checkValidTyCon tc
| isSynTyCon tc
= case synTyConRhs tc of
- OpenSynTyCon _ -> return ()
- SynonymTyCon ty -> checkValidType syn_ctxt ty
+ OpenSynTyCon _ _ -> return ()
+ SynonymTyCon ty -> checkValidType syn_ctxt ty
| otherwise
= -- Check the context on the data decl
checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
-- NB: this check assumes that all the constructors of a given
-- data type use the same type variables
where
- tvs1 = mkVarSet (dataConAllTyVars con1)
- res1 = dataConResTys con1
+ (tvs1, _, _, res1) = dataConSig con1
+ ts1 = mkVarSet tvs1
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 }
+ = do { checkFieldCompat label con1 con2 ts1 res1 res2 fty1 fty2
+ ; checkFieldCompat label con2 con1 ts2 res2 res1 fty2 fty1 }
where
- tvs2 = mkVarSet (dataConAllTyVars con2)
- res2 = dataConResTys con2
+ (tvs2, _, _, res2) = dataConSig con2
+ ts2 = mkVarSet tvs2
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_subst1 = tcMatchTy tvs1 res1 res2
mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
-------------------------------
= setSrcSpan (srcLocSpan (getSrcLoc con)) $
addErrCtxt (dataConCtxt con) $
do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
- ; checkValidType ctxt (dataConUserType con) }
+ ; checkValidType ctxt (dataConUserType con)
+ ; ifM (isNewTyCon tc) (checkNewDataCon con)
+ }
where
ctxt = ConArgCtxt (dataConName con)
-------------------------------
+checkNewDataCon :: DataCon -> TcM ()
+-- Checks for the data constructor of a newtype
+checkNewDataCon con
+ = do { checkTc (isSingleton arg_tys) (newtypeFieldErr con (length arg_tys))
+ -- One argument
+ ; checkTc (null eq_spec) (newtypePredError con)
+ -- Return type is (T a b c)
+ ; checkTc (null ex_tvs && null eq_theta && null dict_theta) (newtypeExError con)
+ -- No existentials
+ ; checkTc (not (any isMarkedStrict (dataConStrictMarks con)))
+ (newtypeStrictError con)
+ -- No strictness
+ }
+ where
+ (_univ_tvs, ex_tvs, eq_spec, eq_theta, dict_theta, arg_tys, _res_ty) = dataConFullSig con
+
+-------------------------------
checkValidClass :: Class -> TcM ()
checkValidClass cls
- = do { -- CHECK ARITY 1 FOR HASKELL 1.4
- gla_exts <- doptM Opt_GlasgowExts
+ = do { constrained_class_methods <- doptM Opt_ConstrainedClassMethods
+ ; multi_param_type_classes <- doptM Opt_MultiParamTypeClasses
+ ; fundep_classes <- doptM Opt_FunctionalDependencies
-- Check that the class is unary, unless GlaExs
; checkTc (notNull tyvars) (nullaryClassErr cls)
- ; checkTc (gla_exts || unary) (classArityErr cls)
+ ; checkTc (multi_param_type_classes || unary) (classArityErr cls)
+ ; checkTc (fundep_classes || null fundeps) (classFunDepsErr cls)
-- Check the super-classes
; checkValidTheta (ClassSCCtxt (className cls)) theta
-- Check the class operations
- ; mappM_ (check_op gla_exts) op_stuff
+ ; mappM_ (check_op constrained_class_methods) op_stuff
-- Check that if the class has generic methods, then the
-- class has only one parameter. We can't do generic
; checkTc (unary || no_generics) (genericMultiParamErr cls)
}
where
- (tyvars, theta, _, op_stuff) = classBigSig cls
+ (tyvars, fundeps, theta, _, _, op_stuff) = classExtraBigSig cls
unary = isSingleton tyvars
no_generics = null [() | (_, GenDefMeth) <- op_stuff]
- check_op gla_exts (sel_id, dm)
+ check_op constrained_class_methods (sel_id, dm)
= addErrCtxt (classOpCtxt sel_id tau) $ do
{ checkValidTheta SigmaCtxt (tail theta)
-- The 'tail' removes the initial (C a) from the
-- class itself, leaving just the method type
+ ; traceTc (text "class op type" <+> ppr op_ty <+> ppr tau)
; checkValidType (FunSigCtxt op_name) tau
-- Check that the type mentions at least one of
- -- the class type variables
- ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
+ -- the class type variables...or at least one reachable
+ -- from one of the class variables. Example: tc223
+ -- class Error e => Game b mv e | b -> mv e where
+ -- newBoard :: MonadState b m => m ()
+ -- Here, MonadState has a fundep m->b, so newBoard is fine
+ ; let grown_tyvars = grow theta (mkVarSet tyvars)
+ ; checkTc (tyVarsOfType tau `intersectsVarSet` grown_tyvars)
(noClassTyVarErr cls sel_id)
-- Check that for a generic method, the type of
op_ty = idType sel_id
(_,theta1,tau1) = tcSplitSigmaTy op_ty
(_,theta2,tau2) = tcSplitSigmaTy tau1
- (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
- | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
+ (theta,tau) | constrained_class_methods = (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
+ -- With -XConstrainedClassMethods, 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!
classArityErr cls
= vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
- parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
+ parens (ptext SLIT("Use -XMultiParamTypeClasses to allow multi-parameter classes"))]
+
+classFunDepsErr cls
+ = vcat [ptext SLIT("Fundeps in class") <+> quotes (ppr cls),
+ parens (ptext SLIT("Use -XFunctionalDependencies to allow fundeps"))]
noClassTyVarErr clas op
= sep [ptext SLIT("The class method") <+> quotes (ppr op),
badGadtDecl tc_name
= vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
- , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
+ , nest 2 (parens $ ptext SLIT("Use -XGADTs to allow GADTs")) ]
badStupidTheta tc_name
= ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
= sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
+newtypeStrictError con
+ = sep [ptext SLIT("A newtype constructor cannot have a strictness annotation,"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
+
+newtypePredError con
+ = sep [ptext SLIT("A newtype constructor must have a return type of form T a1 ... an"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does not")]
+
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]
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")) ]
+ , nest 2 (parens $ ptext SLIT("Use -XKindSignatures to allow kind signatures")) ]
-badKindSigCtxt tc_name
- = vcat [ ptext SLIT("Illegal context in kind signature") <+>
+badFamInstDecl tc_name
+ = vcat [ ptext SLIT("Illegal family instance for") <+>
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")) ]
+ , nest 2 (parens $ ptext SLIT("Use -XTypeFamilies to allow indexed type families")) ]
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")) ]
+ , nest 2 (parens $ ptext SLIT("Family instances can not yet use GADT declarations")) ]
tooManyParmsErr tc_name
- = ptext SLIT("Indexed type instance has too many parameters:") <+>
+ = ptext SLIT("Family 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)
+tooFewParmsErr arity
+ = ptext SLIT("Family instance has too few parameters; expected") <+>
+ ppr arity
+
+wrongNumberOfParmsErr exp_arity
+ = ptext SLIT("Number of parameters must match family declaration; expected")
+ <+> ppr exp_arity
-badBootTyIdxDeclErr = ptext SLIT("Illegal indexed type instance in hs-boot file")
+badBootFamInstDeclErr =
+ ptext SLIT("Illegal family instance in hs-boot file")
+
+wrongKindOfFamily family =
+ ptext SLIT("Wrong category of family instance; declaration was for a") <+>
+ kindOfFamily
+ where
+ kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
+ | isAlgTyCon family = ptext SLIT("data type")
+ | otherwise = pprPanic "wrongKindOfFamily" (ppr family)
emptyConDeclsErr tycon
= sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
- nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]
+ nest 2 $ ptext SLIT("(-XEmptyDataDecls permits this)")]
\end{code}
projects / ghc-hetmet.git / blobdiff