'unsafe' { L _ ITunsafe }
'mdo' { L _ ITmdo }
'iso' { L _ ITiso }
+ 'family' { L _ ITfamily }
'stdcall' { L _ ITstdcallconv }
'ccall' { L _ ITccallconv }
'dotnet' { L _ ITdotnet }
{% do { let { (binds, sigs, ats) =
cvBindsAndSigs (unLoc $4)
; (ctxt, tc, tvs, tparms) = unLoc $2}
- ; checkTyVars tparms False -- only type vars allowed
+ ; checkTyVars tparms -- only type vars allowed
; checkKindSigs ats
; return $ L (comb4 $1 $2 $3 $4)
(mkClassDecl (ctxt, tc, tvs)
-- Type declarations
--
ty_decl :: { LTyClDecl RdrName }
- -- type function signature and equations (w/ type synonyms as special
- -- case); we need to handle all this in one rule to avoid a large
- -- number of shift/reduce conflicts
- : 'type' opt_iso type kind_or_ctype
+ -- ordinary type synonyms
+ : 'type' type '=' ctype
+ -- Note ctype, not sigtype, on the right of '='
+ -- We allow an explicit for-all but we don't insert one
+ -- in type Foo a = (b,b)
+ -- Instead we just say b is out of scope
--
-- Note the use of type for the head; this allows
- -- infix type constructors to be declared and type
- -- patterns for type function equations
- --
- -- We have that `typats :: Maybe [LHsType name]' is `Nothing'
- -- (in the second case alternative) when all arguments are
- -- variables (and we thus have a vanilla type synonym
- -- declaration); otherwise, it contains all arguments as type
- -- patterns.
+ -- infix type constructors to be declared
+ {% do { (tc, tvs, _) <- checkSynHdr $2 False
+ ; return (L (comb2 $1 $4)
+ (TySynonym tc tvs Nothing $4))
+ } }
+
+ -- type family declarations
+ | 'type' 'family' opt_iso type '::' kind
+ -- Note the use of type for the head; this allows
+ -- infix type constructors to be declared
--
- {% case $4 of
- Left kind ->
- do { (tc, tvs, _) <- checkSynHdr $3 False
- ; return (L (comb3 $1 $3 kind)
- (TyFunction tc tvs $2 (unLoc kind)))
- }
- Right ty | not $2 ->
- do { (tc, tvs, typats) <- checkSynHdr $3 True
- ; return (L (comb2 $1 ty)
- (TySynonym tc tvs typats ty)) }
- Right ty | otherwise ->
- parseError (comb2 $1 ty)
- "iso tag is only allowed in kind signatures"
- }
-
- -- kind signature of indexed type
- | data_or_newtype tycl_hdr '::' kind
- {% do { let {(ctxt, tc, tvs, tparms) = unLoc $2}
- ; checkTyVars tparms False -- no type pattern
- ; return $
- L (comb3 $1 $2 $4)
- (mkTyData (unLoc $1) (ctxt, tc, tvs, Nothing)
- (Just (unLoc $4)) [] Nothing) } }
+ {% do { (tc, tvs, _) <- checkSynHdr $4 False
+ ; return (L (comb3 $1 $4 $6)
+ (TyFunction tc tvs $3 (unLoc $6)))
+ } }
+
+ -- type instance declarations
+ | 'type' 'instance' type '=' ctype
+ -- Note the use of type for the head; this allows
+ -- infix type constructors and type patterns
+ --
+ {% do { (tc, tvs, typats) <- checkSynHdr $3 True
+ ; return (L (comb2 $1 $5)
+ (TySynonym tc tvs (Just typats) $5))
+ } }
- -- data type or newtype declaration
+ -- ordinary data type or newtype declaration
| data_or_newtype tycl_hdr constrs deriving
{% do { let {(ctxt, tc, tvs, tparms) = unLoc $2}
- ; tpats <- checkTyVars tparms True -- can have type pats
+ ; checkTyVars tparms -- no type pattern
; return $
L (comb4 $1 $2 $3 $4)
-- We need the location on tycl_hdr in case
-- constrs and deriving are both empty
- (mkTyData (unLoc $1) (ctxt, tc, tvs, tpats)
- Nothing (reverse (unLoc $3)) (unLoc $4)) } }
+ (mkTyData (unLoc $1) (ctxt, tc, tvs, Nothing)
+ Nothing (reverse (unLoc $3)) (unLoc $4)) } }
- -- GADT declaration
+ -- ordinary GADT declaration
| data_or_newtype tycl_hdr opt_kind_sig
'where' gadt_constrlist
deriving
{% do { let {(ctxt, tc, tvs, tparms) = unLoc $2}
- ; tpats <- checkTyVars tparms True -- can have type pats
+ ; checkTyVars tparms -- can have type pats
; return $
L (comb4 $1 $2 $4 $5)
- (mkTyData (unLoc $1) (ctxt, tc, tvs, tpats) $3
- (reverse (unLoc $5)) (unLoc $6)) } }
+ (mkTyData (unLoc $1) (ctxt, tc, tvs, Nothing) $3
+ (reverse (unLoc $5)) (unLoc $6)) } }
+
+ -- data/newtype family
+ | data_or_newtype 'family' tycl_hdr '::' kind
+ {% do { let {(ctxt, tc, tvs, tparms) = unLoc $3}
+ ; checkTyVars tparms -- no type pattern
+ ; return $
+ L (comb3 $1 $2 $5)
+ (mkTyData (unLoc $1) (ctxt, tc, tvs, Nothing)
+ (Just (unLoc $5)) [] Nothing) } }
+
+ -- data/newtype instance declaration
+ | data_or_newtype 'instance' tycl_hdr constrs deriving
+ {% do { let {(ctxt, tc, tvs, tparms) = unLoc $3}
+ -- can have type pats
+ ; return $
+ L (comb4 $1 $3 $4 $5)
+ -- We need the location on tycl_hdr in case
+ -- constrs and deriving are both empty
+ (mkTyData (unLoc $1) (ctxt, tc, tvs, Just tparms)
+ Nothing (reverse (unLoc $4)) (unLoc $5)) } }
+
+ -- GADT instance declaration
+ | data_or_newtype 'instance' tycl_hdr opt_kind_sig
+ 'where' gadt_constrlist
+ deriving
+ {% do { let {(ctxt, tc, tvs, tparms) = unLoc $3}
+ -- can have type pats
+ ; return $
+ L (comb4 $1 $3 $6 $7)
+ (mkTyData (unLoc $1) (ctxt, tc, tvs, Just tparms)
+ $4 (reverse (unLoc $6)) (unLoc $7)) } }
opt_iso :: { Bool }
: { False }
| 'iso' { True }
-kind_or_ctype :: { Either (Located Kind) (LHsType RdrName) }
- : '::' kind { Left (LL (unLoc $2)) }
- | '=' ctype { Right (LL (unLoc $2)) }
- -- Note ctype, not sigtype, on the right of '='
- -- We allow an explicit for-all but we don't insert one
- -- in type Foo a = (b,b)
- -- Instead we just say b is out of scope
-
data_or_newtype :: { Located NewOrData }
: 'data' { L1 DataType }
| 'newtype' { L1 NewType }
: VARID { L1 $! mkUnqual varName (getVARID $1) }
| special_id { L1 $! mkUnqual varName (unLoc $1) }
| 'forall' { L1 $! mkUnqual varName FSLIT("forall") }
+ | 'iso' { L1 $! mkUnqual varName FSLIT("iso") }
+ | 'family' { L1 $! mkUnqual varName FSLIT("family") }
qvarsym :: { Located RdrName }
: varsym { $1 }
-- These special_ids are treated as keywords in various places,
-- but as ordinary ids elsewhere. 'special_id' collects all these
--- except 'unsafe' and 'forall' whose treatment differs depending on context
+-- except 'unsafe', 'forall', 'family', and 'iso' whose treatment differs
+-- depending on context
special_id :: { Located FastString }
special_id
: 'as' { L1 FSLIT("as") }
| 'dynamic' { L1 FSLIT("dynamic") }
| 'stdcall' { L1 FSLIT("stdcall") }
| 'ccall' { L1 FSLIT("ccall") }
- | 'iso' { L1 FSLIT("iso") }
special_sym :: { Located FastString }
special_sym : '!' { L1 FSLIT("!") }
checkContext, -- HsType -> P HsContext
checkPred, -- HsType -> P HsPred
checkTyClHdr, -- LHsContext RdrName -> LHsType RdrName -> P (LHsContext RdrName, Located RdrName, [LHsTyVarBndr RdrName], [LHsType RdrName])
- checkTyVars, -- [LHsType RdrName] -> Bool -> P ()
- checkSynHdr, -- LHsType RdrName -> P (Located RdrName, [LHsTyVarBndr RdrName], Maybe [LHsType RdrName])
+ checkTyVars, -- [LHsType RdrName] -> P ()
+ checkSynHdr, -- LHsType RdrName -> P (Located RdrName, [LHsTyVarBndr RdrName], [LHsType RdrName])
checkKindSigs, -- [LTyClDecl RdrName] -> P ()
checkInstType, -- HsType -> P HsType
checkPattern, -- HsExp -> P HsPat
import Panic
import List ( isSuffixOf, nubBy )
+import Monad ( unless )
\end{code}
return (L l (HsForAllTy Implicit [] (noLoc []) dict_ty))
-- Check whether the given list of type parameters are all type variables
--- (possibly with a kind signature). If the second argument is `False', we
+-- (possibly with a kind signature). If the second argument is `False',
-- only type variables are allowed and we raise an error on encountering a
--- non-variable; otherwise, we return the entire list parameters iff at least
--- one is not a variable.
+-- non-variable; otherwise, we allow non-variable arguments and return the
+-- entire list of parameters.
--
-checkTyVars :: [LHsType RdrName] -> Bool -> P (Maybe [LHsType RdrName])
-checkTyVars tparms nonVarsOk =
- do
- areVars <- mapM chk tparms
- return $ if and areVars then Nothing else Just tparms
+checkTyVars :: [LHsType RdrName] -> P ()
+checkTyVars tparms = mapM_ chk tparms
where
-- Check that the name space is correct!
chk (L l (HsKindSig (L _ (HsTyVar tv)) k))
- | isRdrTyVar tv = return True
+ | isRdrTyVar tv = return ()
chk (L l (HsTyVar tv))
- | isRdrTyVar tv = return True
- chk (L l other)
- | nonVarsOk = return False
- | otherwise =
+ | isRdrTyVar tv = return ()
+ chk (L l other) =
parseError l "Type found where type variable expected"
-- Check whether the type arguments in a type synonym head are simply
-- indicate a vanilla type synonym.
--
checkSynHdr :: LHsType RdrName
- -> Bool -- non-variables admitted?
+ -> Bool -- is type instance?
-> P (Located RdrName, -- head symbol
[LHsTyVarBndr RdrName], -- parameters
- Maybe [LHsType RdrName]) -- type patterns
-checkSynHdr ty nonVarsOk =
+ [LHsType RdrName]) -- type patterns
+checkSynHdr ty isTyInst =
do { (_, tc, tvs, tparms) <- checkTyClHdr (noLoc []) ty
- ; typats <- checkTyVars tparms nonVarsOk
- ; return (tc, tvs, typats) }
+ ; unless isTyInst $ checkTyVars tparms
+ ; return (tc, tvs, tparms) }
-- Well-formedness check and decomposition of type and class heads.