Commit ac9c1e5d authored by chak@cse.unsw.edu.au.'s avatar chak@cse.unsw.edu.au.

Use family and instance keyword to identify indexed types

Tue Aug 15 20:16:00 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
  * Use family and instance keyword to identify indexed types
parent 3734da50
......@@ -377,6 +377,7 @@ data Token
| ITdotnet
| ITmdo
| ITiso
| ITfamily
-- Pragmas
| ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
......@@ -501,6 +502,7 @@ isSpecial ITccallconv = True
isSpecial ITstdcallconv = True
isSpecial ITmdo = True
isSpecial ITiso = True
isSpecial ITfamily = True
isSpecial _ = False
-- the bitmap provided as the third component indicates whether the
......@@ -542,6 +544,7 @@ reservedWordsFM = listToUFM $
( "forall", ITforall, bit tvBit),
( "mdo", ITmdo, bit glaExtsBit),
( "iso", ITiso, bit glaExtsBit),
( "family", ITfamily, bit glaExtsBit),
( "foreign", ITforeign, bit ffiBit),
( "export", ITexport, bit ffiBit),
......
......@@ -186,6 +186,7 @@ incorrect.
'unsafe' { L _ ITunsafe }
'mdo' { L _ ITmdo }
'iso' { L _ ITiso }
'family' { L _ ITfamily }
'stdcall' { L _ ITstdcallconv }
'ccall' { L _ ITccallconv }
'dotnet' { L _ ITdotnet }
......@@ -468,7 +469,7 @@ cl_decl :: { LTyClDecl RdrName }
{% 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)
......@@ -477,79 +478,97 @@ cl_decl :: { LTyClDecl RdrName }
-- 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 }
......@@ -1444,6 +1463,8 @@ varid_no_unsafe :: { Located RdrName }
: 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 }
......@@ -1467,7 +1488,8 @@ varsym_no_minus :: { Located RdrName } -- varsym not including '-'
-- 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") }
......@@ -1478,7 +1500,6 @@ special_id
| 'dynamic' { L1 FSLIT("dynamic") }
| 'stdcall' { L1 FSLIT("stdcall") }
| 'ccall' { L1 FSLIT("ccall") }
| 'iso' { L1 FSLIT("iso") }
special_sym :: { Located FastString }
special_sym : '!' { L1 FSLIT("!") }
......
......@@ -36,8 +36,8 @@ module RdrHsSyn (
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
......@@ -70,6 +70,7 @@ import FastString
import Panic
import List ( isSuffixOf, nubBy )
import Monad ( unless )
\end{code}
......@@ -378,25 +379,20 @@ checkInstType (L l t)
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
......@@ -405,14 +401,14 @@ checkTyVars tparms nonVarsOk =
-- 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.
......
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