-- friends:
import HsSyn ( LHsType )
-import TypeRep ( Type(..), PredType(..), TyNote(..), -- Friend; can see representation
- Kind, ThetaType
+import TypeRep ( Type(..), PredType(..), -- Friend; can see representation
+ ThetaType
)
import TcType ( TcType, TcThetaType, TcTauType, TcPredType,
TcTyVarSet, TcKind, TcTyVar, TcTyVarDetails(..),
MetaDetails(..), SkolemInfo(..), isMetaTyVar, metaTvRef,
- tcCmpPred, isClassPred,
+ tcCmpPred, tcEqType, isClassPred,
tcSplitPhiTy, tcSplitPredTy_maybe, tcSplitAppTy_maybe,
- tcSplitTyConApp_maybe, tcSplitForAllTys,
- tcIsTyVarTy, tcSplitSigmaTy, tcIsTyVarTy,
+ tcValidInstHeadTy, tcSplitForAllTys,
+ tcIsTyVarTy, tcSplitSigmaTy,
isUnLiftedType, isIPPred, isImmutableTyVar,
typeKind, isFlexi, isSkolemTyVar,
mkAppTy, mkTyVarTy, mkTyVarTys,
tyVarsOfPred, getClassPredTys_maybe,
- tyVarsOfType, tyVarsOfTypes,
+ tyVarsOfType, tyVarsOfTypes, tcView,
pprPred, pprTheta, pprClassPred )
-import Kind ( Kind(..), KindVar(..), mkKindVar, isSubKind,
+import Kind ( Kind(..), KindVar, kindVarRef, mkKindVar, isSubKind,
isLiftedTypeKind, isArgTypeKind, isOpenTypeKind,
liftedTypeKind, defaultKind
)
import Name ( Name, setNameUnique, mkSysTvName )
import VarSet
import VarEnv
-import CmdLineOpts ( dopt, DynFlag(..) )
+import DynFlags ( dopt, DynFlag(..) )
import UniqSupply ( uniqsFromSupply )
-import Util ( nOfThem, isSingleton, equalLength, notNull )
-import ListSetOps ( removeDups )
+import Util ( nOfThem, isSingleton, notNull )
+import ListSetOps ( removeDups, findDupsEq )
import SrcLoc ( unLoc )
import Outputable
\end{code}
\begin{code}
data LookupTyVarResult -- The result of a lookupTcTyVar call
- = DoneTv TcTyVarDetails
+ = DoneTv TcTyVarDetails -- Unrefined SkolemTv or virgin MetaTv/SigSkolTv
| IndirectTv Bool TcType
-- True => This is a non-wobbly type refinement,
-- gotten from GADT match unification
go (TyConApp tycon tys) = mappM go tys `thenM` \ tys' ->
returnM (TyConApp tycon tys')
- go (NoteTy (SynNote ty1) ty2) = go ty1 `thenM` \ ty1' ->
- go ty2 `thenM` \ ty2' ->
- returnM (NoteTy (SynNote ty1') ty2')
-
- go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard free-tyvar annotations
+ go (NoteTy _ ty2) = go ty2 -- Discard free-tyvar annotations
go (PredTy p) = go_pred p `thenM` \ p' ->
returnM (PredTy p')
\begin{code}
readKindVar :: KindVar -> TcM (Maybe TcKind)
writeKindVar :: KindVar -> TcKind -> TcM ()
-readKindVar (KVar _ ref) = readMutVar ref
-writeKindVar (KVar _ ref) val = writeMutVar ref (Just val)
+readKindVar kv = readMutVar (kindVarRef kv)
+writeKindVar kv val = writeMutVar (kindVarRef kv) (Just val)
-------------
zonkTcKind :: TcKind -> TcM TcKind
\begin{code}
data UserTypeCtxt
= FunSigCtxt Name -- Function type signature
+ -- Also used for types in SPECIALISE pragmas
| ExprSigCtxt -- Expression type signature
| ConArgCtxt Name -- Data constructor argument
| TySynCtxt Name -- RHS of a type synonym decl
| ForSigCtxt Name -- Foreign inport or export signature
| RuleSigCtxt Name -- Signature on a forall'd variable in a RULE
| DefaultDeclCtxt -- Types in a default declaration
+ | SpecInstCtxt -- SPECIALISE instance pragma
-- Notes re TySynCtxt
-- We allow type synonyms that aren't types; e.g. type List = []
pprUserTypeCtxt ty (ForSigCtxt n) = sep [ptext SLIT("In the foreign declaration:"), pp_sig n ty]
pprUserTypeCtxt ty (RuleSigCtxt n) = sep [ptext SLIT("In the type signature:"), pp_sig n ty]
pprUserTypeCtxt ty DefaultDeclCtxt = sep [ptext SLIT("In a type in a `default' declaration:"), nest 2 (ppr ty)]
+pprUserTypeCtxt ty SpecInstCtxt = sep [ptext SLIT("In a SPECIALISE instance pragma:"), nest 2 (ppr ty)]
pp_sig n ty = nest 2 (ppr n <+> dcolon <+> ppr ty)
\end{code}
-- constructor, hence rank 1
ForSigCtxt _ -> Rank 1
RuleSigCtxt _ -> Rank 1
+ SpecInstCtxt -> Rank 1
actual_kind = typeKind ty
ExprSigCtxt -> isOpenTypeKind actual_kind
GenPatCtxt -> isLiftedTypeKind actual_kind
ForSigCtxt _ -> isLiftedTypeKind actual_kind
- other -> isArgTypeKind actual_kind
+ other -> isArgTypeKind actual_kind
ubx_tup | not gla_exts = UT_NotOk
| otherwise = case ctxt of
check_tau_type rank ubx_tup (AppTy ty1 ty2)
= check_arg_type ty1 `thenM_` check_arg_type ty2
-check_tau_type rank ubx_tup (NoteTy (SynNote syn) ty)
- -- Synonym notes are built only when the synonym is
- -- saturated (see Type.mkSynTy)
- = doptM Opt_GlasgowExts `thenM` \ gla_exts ->
- (if gla_exts then
- -- If -fglasgow-exts then don't check the 'note' part.
- -- This allows us to instantiate a synonym defn with a
- -- for-all type, or with a partially-applied type synonym.
- -- e.g. type T a b = a
- -- type S m = m ()
- -- f :: S (T Int)
- -- Here, T is partially applied, so it's illegal in H98.
- -- But if you expand S first, then T we get just
- -- f :: Int
- -- which is fine.
- returnM ()
- else
- -- For H98, do check the un-expanded part
- check_tau_type rank ubx_tup syn
- ) `thenM_`
-
- check_tau_type rank ubx_tup ty
-
check_tau_type rank ubx_tup (NoteTy other_note ty)
= check_tau_type rank ubx_tup ty
= -- NB: Type.mkSynTy builds a TyConApp (not a NoteTy) for an unsaturated
-- synonym application, leaving it to checkValidType (i.e. right here)
-- to find the error
- checkTc syn_arity_ok arity_msg `thenM_`
- mappM_ check_arg_type tys
+ do { -- It's OK to have an *over-applied* type synonym
+ -- data Tree a b = ...
+ -- type Foo a = Tree [a]
+ -- f :: Foo a b -> ...
+ ; case tcView ty of
+ Just ty' -> check_tau_type rank ubx_tup ty' -- Check expansion
+ Nothing -> failWithTc arity_msg
+
+ ; gla_exts <- doptM Opt_GlasgowExts
+ ; if gla_exts then
+ -- If -fglasgow-exts then don't check the type arguments
+ -- This allows us to instantiate a synonym defn with a
+ -- for-all type, or with a partially-applied type synonym.
+ -- e.g. type T a b = a
+ -- type S m = m ()
+ -- f :: S (T Int)
+ -- Here, T is partially applied, so it's illegal in H98.
+ -- But if you expand S first, then T we get just
+ -- f :: Int
+ -- which is fine.
+ returnM ()
+ else
+ -- For H98, do check the type args
+ mappM_ check_arg_type tys
+ }
| isUnboxedTupleTyCon tc
= doptM Opt_GlasgowExts `thenM` \ gla_exts ->
where
ubx_tup_ok gla_exts = case ubx_tup of { UT_Ok -> gla_exts; other -> False }
- syn_arity_ok = tc_arity <= n_args
- -- It's OK to have an *over-applied* type synonym
- -- data Tree a b = ...
- -- type Foo a = Tree [a]
- -- f :: Foo a b -> ...
n_args = length tys
tc_arity = tyConArity tc
-------------------------
check_class_pred_tys dflags ctxt tys
= case ctxt of
+ TypeCtxt -> True -- {-# SPECIALISE instance Eq (T Int) #-} is fine
InstHeadCtxt -> True -- We check for instance-head
-- formation in checkValidInstHead
- InstThetaCtxt -> undecidable_ok || all tcIsTyVarTy tys
+ InstThetaCtxt -> undecidable_ok || distinct_tyvars tys
other -> gla_exts || all tyvar_head tys
where
undecidable_ok = dopt Opt_AllowUndecidableInstances dflags
gla_exts = dopt Opt_GlasgowExts dflags
-------------------------
+distinct_tyvars tys -- Check that the types are all distinct type variables
+ = all tcIsTyVarTy tys && null (findDupsEq tcEqType tys)
+
+-------------------------
tyvar_head ty -- Haskell 98 allows predicates of form
| tcIsTyVarTy ty = True -- C (a ty1 .. tyn)
| otherwise -- where a is a type variable
ptext SLIT("While checking") <+> pprSourceTyCtxt ctxt ]
badSourceTyErr sty = ptext SLIT("Illegal constraint") <+> pprPred sty
-predTyVarErr pred = ptext SLIT("Non-type variables in constraint:") <+> pprPred pred
+predTyVarErr pred = sep [ptext SLIT("Non-type variables, or repeated type variables,"),
+ nest 2 (ptext SLIT("in the constraint:") <+> pprPred pred)]
dupPredWarn dups = ptext SLIT("Duplicate constraint(s):") <+> pprWithCommas pprPred (map head dups)
arityErr kind name n m
| dopt Opt_GlasgowExts dflags
= check_tyvars dflags clas tys
- -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
+ -- WITH HASKELL 98, MUST HAVE C (T a b c)
| isSingleton tys,
- Just (tycon, arg_tys) <- tcSplitTyConApp_maybe first_ty,
- not (isSynTyCon tycon), -- ...but not a synonym
- all tcIsTyVarTy arg_tys, -- Applied to type variables
- equalLength (varSetElems (tyVarsOfTypes arg_tys)) arg_tys
- -- This last condition checks that all the type variables are distinct
+ tcValidInstHeadTy first_ty
= returnM ()
| otherwise
= failWithTc (instTypeErr (pprClassPred clas tys) head_shape_msg)
where
- (first_ty : _) = tys
+ (first_ty : _) = tys
head_shape_msg = parens (text "The instance type must be of form (T a b c)" $$
text "where T is not a synonym, and a,b,c are distinct type variables")
projects / ghc-hetmet.git / blobdiff