Unused, unused,
Fixity(..), FixityDirection(..),
- defaultFixity, maxPrecedence, negateFixity, negatePrecedence,
+ defaultFixity, maxPrecedence,
+ arrowFixity, negateFixity, negatePrecedence,
+ compareFixity,
IPName(..), ipNameName, mapIPName,
negateFixity :: Fixity
negateFixity = Fixity negatePrecedence InfixL -- Precedence of unary negate is wired in as infixl 6!
+arrowFixity :: Fixity -- Fixity of '->' in types
+arrowFixity = Fixity 0 InfixR
+
negatePrecedence :: Int
negatePrecedence = 6
\end{code}
+Consider
+
+\begin{verbatim}
+ a `op1` b `op2` c
+\end{verbatim}
+@(compareFixity op1 op2)@ tells which way to arrange appication, or
+whether there's an error.
+
+\begin{code}
+compareFixity :: Fixity -> Fixity
+ -> (Bool, -- Error please
+ Bool) -- Associate to the right: a op1 (b op2 c)
+compareFixity (Fixity prec1 dir1) (Fixity prec2 dir2)
+ = case prec1 `compare` prec2 of
+ GT -> left
+ LT -> right
+ EQ -> case (dir1, dir2) of
+ (InfixR, InfixR) -> right
+ (InfixL, InfixL) -> left
+ _ -> error_please
+ where
+ right = (False, True)
+ left = (False, False)
+ error_please = (True, False)
+\end{code}
+
%************************************************************************
%* *
\begin{code}
module HsTypes (
- HsType(..), HsTyVarBndr(..),
+ HsType(..), HsTyVarBndr(..), HsTyOp(..),
, HsContext, HsPred(..)
, HsTupCon(..), hsTupParens, mkHsTupCon,
, hsUsOnce, hsUsMany
| HsTupleTy (HsTupCon name)
[HsType name] -- Element types (length gives arity)
- -- Generics
- | HsOpTy (HsType name) name (HsType name)
- | HsNumTy Integer
+
+ | HsOpTy (HsType name) (HsTyOp name) (HsType name)
+ | HsNumTy Integer -- Generics only
-- these next two are only used in interfaces
| HsPredTy (HsPred name)
Kind -- A type with a kind signature
+data HsTyOp name = HsArrow | HsTyOp name
+ -- Function arrows from *source* get read in as HsOpTy t1 HsArrow t2
+ -- But when we generate or parse interface files, we use HsFunTy.
+ -- This keeps interfaces a bit smaller, because there are a lot of arrows
+
-----------------------
hsUsOnce, hsUsMany :: HsType RdrName
hsUsOnce = HsTyVar (mkUnqual tvName FSLIT(".")) -- deep magic
instance (Outputable name) => Outputable (HsType name) where
ppr ty = pprHsType ty
+instance (Outputable name) => Outputable (HsTyOp name) where
+ ppr HsArrow = ftext FSLIT("->")
+ ppr (HsTyOp n) = ppr n
+
instance (Outputable name) => Outputable (HsTyVarBndr name) where
ppr (UserTyVar name) = ppr name
ppr (IfaceTyVar name kind) = pprHsTyVarBndr name kind
= eq_hsPred env p1 p2
eq_hsType env (HsOpTy lty1 op1 rty1) (HsOpTy lty2 op2 rty2)
- = eq_hsVar env op1 op2 && eq_hsType env lty1 lty2 && eq_hsType env rty1 rty2
+ = eq_hsOp env op1 op2 && eq_hsType env lty1 lty2 && eq_hsType env rty1 rty2
eq_hsType env ty1 ty2 = False
+eq_hsOp env (HsTyOp n1) (HsTyOp n2) = eq_hsVar env n1 n2
+eq_hsOp env HsArrow HsArrow = True
+eq_hsOp env op1 op2 = False
+
-------------------
eq_hsContext env a b = eqListBy (eq_hsPred env) a b
ac <- get bh
return (HsTupCon aa ab ac)
+instance (Binary name) => Binary (HsTyOp name) where
+ put_ bh HsArrow = putByte bh 0
+ put_ bh (HsTyOp n) = do putByte bh 1
+ put_ bh n
+
+ get bh = do h <- getByte bh
+ case h of
+ 0 -> return HsArrow
+ 1 -> do a <- get bh
+ return (HsTyOp a)
+
instance (Binary name) => Binary (HsType name) where
put_ bh (HsForAllTy aa ab ac) = do
putByte bh 0
, checkContext -- HsType -> P HsContext
, checkPred -- HsType -> P HsPred
, checkTyVars -- [HsTyVar] -> P [HsType]
+ , checkTyClHdr -- HsType -> (name,[tyvar])
, checkInstType -- HsType -> P HsType
, checkPattern -- HsExp -> P HsPat
, checkPatterns -- SrcLoc -> [HsExp] -> P [HsPat]
chk (HsTyVar tv) = returnP (UserTyVar tv)
chk other = parseError "Type found where type variable expected"
+checkTyClHdr :: RdrNameHsType -> P (RdrName, [RdrNameHsTyVar])
+-- The header of a type or class decl should look like
+-- (C a, D b) => T a b
+-- or T a b
+-- or a + b
+-- etc
+checkTyClHdr ty
+ = go ty []
+ where
+ go (HsTyVar tc) acc
+ | not (isRdrTyVar tc) = checkTyVars acc `thenP` \ tvs ->
+ returnP (tc, tvs)
+ go (HsOpTy t1 (HsTyOp tc) t2) acc = checkTyVars (t1:t2:acc) `thenP` \ tvs ->
+ returnP (tc, tvs)
+ go (HsAppTy t1 t2) acc = go t1 (t2:acc)
+ go other acc = parseError "Malformed LHS to type of class declaration"
+
checkContext :: RdrNameHsType -> P RdrNameContext
checkContext (HsTupleTy _ ts) -- (Eq a, Ord b) shows up as a tuple type
= mapP checkPred ts
{- -*-haskell-*-
-----------------------------------------------------------------------------
-$Id: Parser.y,v 1.97 2002/05/10 13:34:18 simonpj Exp $
+$Id: Parser.y,v 1.98 2002/05/27 15:28:08 simonpj Exp $
Haskell grammar.
-----------------------------------------------------------------------------
Conflicts: 21 shift/reduce, -=chak[4Feb2]
-9 for abiguity in 'if x then y else z + 1'
+11 for abiguity in 'if x then y else z + 1' [State 128]
(shift parses as 'if x then y else (z + 1)', as per longest-parse rule)
8 because op might be: - ! * . `x` VARSYM CONSYM QVARSYM QCONSYM
-1 for ambiguity in 'if x then y else z :: T'
- (shift parses as 'if x then y else (z :: T)', as per longest-parse rule)
-1 for ambiguity in 'if x then y else z with ?x=3'
- (shift parses as 'if x then y else (z with ?x=3)'
-3 for ambiguity in 'case x of y :: a -> b'
- (don't know whether to reduce 'a' as a btype or shift the '->'.
- conclusion: bogus expression anyway, doesn't matter)
-
-1 for ambiguity in '{-# RULES "name" [ ... #-}
+1 for ambiguity in '{-# RULES "name" [ ... #-} [State 210]
we don't know whether the '[' starts the activation or not: it
might be the start of the declaration with the activation being
empty. --SDM 1/4/2002
-1 for ambiguity in '{-# RULES "name" forall = ... #-}'
+1 for ambiguity in '{-# RULES "name" forall = ... #-}' [State 412]
since 'forall' is a valid variable name, we don't know whether
to treat a forall on the input as the beginning of a quantifier
or the beginning of the rule itself. Resolving to shift means
This saves explicitly defining a grammar for the rule lhs that
doesn't include 'forall'.
-1 for ambiguity in 'let ?x ...'
+1 for ambiguity in 'let ?x ...' [State 278]
the parser can't tell whether the ?x is the lhs of a normal binding or
an implicit binding. Fortunately resolving as shift gives it the only
sensible meaning, namely the lhs of an implicit binding.
-6 for conflicts between `fdecl' and `fdeclDEPRECATED', which are resolved
- correctly, and moreover, should go away when `fdeclDEPRECATED' is removed.
+
+8 for ambiguity in 'e :: a `b` c'. Does this mean [States 238,267]
+ (e::a) `b` c, or
+ (e :: (a `b` c))
+
+6 for conflicts between `fdecl' and `fdeclDEPRECATED', [States 402,403]
+ which are resolved correctly, and moreover,
+ should go away when `fdeclDEPRECATED' is removed.
+
+1 for ambiguity in 'if x then y else z :: T'
+ (shift parses as 'if x then y else (z :: T)', as per longest-parse rule)
+1 for ambiguity in 'if x then y else z with ?x=3'
+ (shift parses as 'if x then y else (z with ?x=3)'
+3 for ambiguity in 'case x of y :: a -> b'
+ (don't know whether to reduce 'a' as a btype or shift the '->'.
+ conclusion: bogus expression anyway, doesn't matter)
+
-----------------------------------------------------------------------------
-}
| topdecl { [$1] }
topdecl :: { RdrBinding }
- : srcloc 'type' tycon tv_bndrs '=' ctype
+ : srcloc 'type' syn_hdr '=' ctype
-- Note ctype, not sigtype.
-- 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
- { RdrHsDecl (TyClD (TySynonym $3 $4 $6 $1)) }
+ { let (tc,tvs) = $3
+ in RdrHsDecl (TyClD (TySynonym tc tvs $5 $1)) }
| srcloc 'data' tycl_hdr constrs deriving
| '{-# RULES' rules '#-}' { $2 }
| decl { $1 }
+syn_hdr :: { (RdrName, [RdrNameHsTyVar]) } -- We don't retain the syntax of an infix
+ -- type synonym declaration. Oh well.
+ : tycon tv_bndrs { ($1, $2) }
+ | tv_bndr tyconop tv_bndr { ($2, [$1,$3]) }
+
-- tycl_hdr parses the header of a type or class decl,
-- which takes the form
-- T a b
-- (Eq a, Ord b) => T a b
-- Rather a lot of inlining here, else we get reduce/reduce errors
tycl_hdr :: { (RdrNameContext, RdrName, [RdrNameHsTyVar]) }
+ : context '=>' type {% checkTyClHdr $3 `thenP` \ (tc,tvs) ->
+ returnP ($1, tc, tvs) }
+ | type {% checkTyClHdr $1 `thenP` \ (tc,tvs) ->
+ returnP ([], tc, tvs) }
+
+{-
: '(' comma_types1 ')' '=>' gtycon tv_bndrs
{% mapP checkPred $2 `thenP` \ cxt ->
returnP (cxt, $5, $6) }
-- an error in the renamer if some non-H98 form is used and
-- -fglasgow-exts is not given.) -=chak
+atypes0 :: { [RdrNameHsType] }
+ : atypes1 { $1 }
+ | {- empty -} { [] }
+
+atypes1 :: { [RdrNameHsType] }
+ : atype { [$1] }
+ | atype atypes1 { $1 : $2 }
+-}
+
decls :: { [RdrBinding] }
: decls ';' decl { $3 : $1 }
| decls ';' { $1 }
: btype {% checkContext $1 }
type :: { RdrNameHsType }
- : gentype '->' type { HsFunTy $1 $3 }
- | ipvar '::' type { mkHsIParamTy $1 $3 }
+ : ipvar '::' gentype { mkHsIParamTy $1 $3 }
| gentype { $1 }
gentype :: { RdrNameHsType }
: btype { $1 }
--- Generics
- | atype tyconop atype { HsOpTy $1 $2 $3 }
+ | btype qtyconop gentype { HsOpTy $1 (HsTyOp $2) $3 }
+ | btype '->' gentype { HsOpTy $1 HsArrow $3 }
btype :: { RdrNameHsType }
: btype atype { HsAppTy $1 $2 }
: type { [$1] }
| type ',' comma_types1 { $1 : $3 }
-atypes0 :: { [RdrNameHsType] }
- : atypes1 { $1 }
- | {- empty -} { [] }
-
-atypes1 :: { [RdrNameHsType] }
- : atype { [$1] }
- | atype atypes1 { $1 : $2 }
-
tv_bndrs :: { [RdrNameHsTyVar] }
: tv_bndr tv_bndrs { $1 : $2 }
| {- empty -} { [] }
: aexp1 '{' fbinds '}' {% (mkRecConstrOrUpdate $1
(reverse $3)) }
| aexp2 { $1 }
-
--- Here was the syntax for type applications that I was planning
--- but there are difficulties (e.g. what order for type args)
--- so it's not enabled yet.
--- | var_or_con '{|' gentype '|}' { (HsApp $1 (HsType $3)) }
+ | var_or_con '{|' gentype '|}' { HsApp $1 (HsType $3) }
var_or_con :: { RdrNameHsExpr }
| '`' qconid '`' { $2 }
-----------------------------------------------------------------------------
+-- Type constructors
+
+tycon :: { RdrName } -- Unqualified
+ : CONID { mkUnqual tcClsName $1 }
+
+tyconop :: { RdrName } -- Unqualified
+ : CONSYM { mkUnqual tcClsName $1 }
+ | '`' tyvar '`' { $2 }
+ | '`' tycon '`' { $2 }
+
+qtycon :: { RdrName } -- Qualified or unqualified
+ : QCONID { mkQual tcClsName $1 }
+ | tycon { $1 }
+
+qtyconop :: { RdrName } -- Qualified or unqualified
+ : QCONSYM { mkQual tcClsName $1 }
+ | '`' QCONID '`' { mkQual tcClsName $2 }
+ | tyconop { $1 }
+
+-----------------------------------------------------------------------------
-- Any operator
op :: { RdrName } -- used in infix decls
| 'ccall' { FSLIT("ccall") }
-----------------------------------------------------------------------------
--- ConIds
-
-qconid :: { RdrName } -- Qualified or unqualifiedb
- : conid { $1 }
- | QCONID { mkQual dataName $1 }
-
-conid :: { RdrName }
- : CONID { mkUnqual dataName $1 }
-
------------------------------------------------------------------------------
--- ConSyms
-
-qconsym :: { RdrName } -- Qualified or unqualifiedb
- : consym { $1 }
- | QCONSYM { mkQual dataName $1 }
-
-consym :: { RdrName }
- : CONSYM { mkUnqual dataName $1 }
-
------------------------------------------------------------------------------
--- VarSyms
+-- Variables
qvarsym :: { RdrName }
: varsym { $1 }
| '*' { FSLIT("*") }
-----------------------------------------------------------------------------
+-- Data constructors
+
+qconid :: { RdrName } -- Qualified or unqualifiedb
+ : conid { $1 }
+ | QCONID { mkQual dataName $1 }
+
+conid :: { RdrName }
+ : CONID { mkUnqual dataName $1 }
+
+qconsym :: { RdrName } -- Qualified or unqualified
+ : consym { $1 }
+ | QCONSYM { mkQual dataName $1 }
+
+consym :: { RdrName }
+ : CONSYM { mkUnqual dataName $1 }
+
+
+-----------------------------------------------------------------------------
-- Literals
literal :: { HsLit }
'.':unpackFS (snd $1)))
}
-tycon :: { RdrName }
- : CONID { mkUnqual tcClsName $1 }
-
-tyconop :: { RdrName }
- : CONSYM { mkUnqual tcClsName $1 }
-
-qtycon :: { RdrName } -- Qualified or unqualified
- : QCONID { mkQual tcClsName $1 }
- | tycon { $1 }
-
-qtyconop :: { RdrName } -- Qualified or unqualified
- : QCONSYM { mkQual tcClsName $1 }
- | tyconop { $1 }
-
commas :: { Int }
: commas ',' { $1 + 1 }
| ',' { 2 }
unitAvailEnv, availEnvElts, availNames,
plusAvailEnv, groupAvails, warnUnusedImports,
warnUnusedLocalBinds, warnUnusedModules,
- lookupSrcName, getImplicitStmtFVs,
+ lookupSrcName, getImplicitStmtFVs, mkTopFixityEnv,
getImplicitModuleFVs, newGlobalName, unQualInScope,
ubiquitousNames, lookupOccRn, checkMain,
plusGlobalRdrEnv, mkGlobalRdrEnv
recordLocalSlurps binders `thenRn_`
closeDecls rn_local_decls fvs `thenRn` \ final_decls ->
- -- Bail out if we fail
+ -- Bail out if we fail (but dump debug output anyway for debugging)
+ rnDump final_decls `thenRn_`
checkErrsRn `thenRn` \ no_errs_so_far ->
if not no_errs_so_far then
returnRn (print_unqualified, Nothing)
else
- rnDump final_decls [] `thenRn_`
let
mod_iface = ModIface { mi_module = this_module,
mi_package = opt_InPackage,
checkErrsRn `thenRn` \ no_errs_so_far ->
if not no_errs_so_far then
-- Found errors already, so exit now
- rnDump [] [] `thenRn_`
returnRn (print_unqualified, Nothing)
else
checkErrsRn `thenRn` \ no_errs_so_far ->
if not no_errs_so_far then
-- Found errors already, so exit now
- rnDump [] rn_local_decls `thenRn_`
+ rnDump rn_local_decls `thenRn_`
returnRn (print_unqualified, Nothing)
else
-- SLURP IN ALL THE NEEDED DECLARATIONS
slurpImpDecls needed_fvs `thenRn` \ rn_imp_decls ->
- rnDump rn_imp_decls rn_local_decls `thenRn_`
-- GENERATE THE VERSION/USAGE INFO
mkImportInfo mod_name imports `thenRn` \ my_usages ->
rr_main = maybe_main_name }
in
+ rnDump final_decls `thenRn_`
+ rnStats rn_imp_decls `thenRn_`
+
-- REPORT UNUSED NAMES, AND DEBUG DUMP
reportUnusedNames mod_iface print_unqualified
imports full_avail_env gbl_env
\begin{code}
fixitiesFromLocalDecls :: GlobalRdrEnv -> [RdrNameHsDecl] -> RnMG LocalFixityEnv
fixitiesFromLocalDecls gbl_env decls
- = foldlRn getFixities emptyNameEnv decls `thenRn` \ env ->
+ = mkTopFixityEnv gbl_env (foldr get_fix_sigs [] decls) `thenRn` \ env ->
traceRn (text "fixity env" <+> vcat (map ppr (nameEnvElts env))) `thenRn_`
returnRn env
where
- getFixities :: LocalFixityEnv -> RdrNameHsDecl -> RnMG LocalFixityEnv
- getFixities acc (FixD fix)
- = fix_decl acc fix
-
- getFixities acc (TyClD (ClassDecl { tcdSigs = sigs}))
- = foldlRn fix_decl acc [sig | FixSig sig <- sigs]
- -- Get fixities from class decl sigs too.
- getFixities acc other_decl
- = returnRn acc
-
- fix_decl acc sig@(FixitySig rdr_name fixity loc)
- = -- Check for fixity decl for something not declared
- pushSrcLocRn loc $
- lookupSrcName gbl_env rdr_name `thenRn` \ name ->
-
- -- Check for duplicate fixity decl
- case lookupNameEnv acc name of
- Just (FixitySig _ _ loc') -> addErrRn (dupFixityDecl rdr_name loc loc') `thenRn_`
- returnRn acc ;
-
- Nothing -> returnRn (extendNameEnv acc name (FixitySig name fixity loc))
+ get_fix_sigs (FixD fix) acc = fix:acc
+ get_fix_sigs (TyClD (ClassDecl { tcdSigs = sigs})) acc
+ = [sig | FixSig sig <- sigs] ++ acc -- Get fixities from class decl sigs too.
+ get_fix_sigs other_decl acc = acc
\end{code}
map TyClD tycl_decls
needed = unionManyNameSets (map ruleDeclFVs rule_decls) `unionNameSets`
unionManyNameSets (map instDeclFVs inst_decls) `unionNameSets`
- unionManyNameSets (map tyClDeclFVs tycl_decls)
+ unionManyNameSets (map tyClDeclFVs tycl_decls) `unionNameSets`
+ ubiquitousNames
+ -- Data type decls with record selectors,
+ -- which may appear in the decls, need unpackCString
+ -- and friends. It's easier to just grab them right now.
+
local_names = foldl add emptyNameSet tycl_decls
add names decl = addListToNameSet names (map fst (tyClDeclSysNames decl ++ tyClDeclNames decl))
in
-
recordLocalSlurps local_names `thenRn_`
-- Do the transitive closure
- closeDecls decls (needed `plusFV` implicit_fvs) `thenRn` \closed_decls ->
- rnDump [] closed_decls `thenRn_`
+ closeDecls decls needed `thenRn` \closed_decls ->
+ rnDump closed_decls `thenRn_`
returnRn closed_decls
- where
- implicit_fvs = ubiquitousNames -- Data type decls with record selectors,
- -- which may appear in the decls, need unpackCString
- -- and friends. It's easier to just grab them right now.
\end{code}
%*********************************************************
where
n_mod = moduleName (nameModule n)
-rnDump :: [RenamedHsDecl] -- Renamed imported decls
- -> [RenamedHsDecl] -- Renamed local decls
+rnDump :: [RenamedHsDecl] -- Renamed decls
-> RnMG ()
-rnDump imp_decls local_decls
+rnDump decls
= doptRn Opt_D_dump_rn_trace `thenRn` \ dump_rn_trace ->
doptRn Opt_D_dump_rn_stats `thenRn` \ dump_rn_stats ->
doptRn Opt_D_dump_rn `thenRn` \ dump_rn ->
getIfacesRn `thenRn` \ ifaces ->
- ioToRnM (do { dumpIfSet (dump_rn_trace || dump_rn_stats || dump_rn)
- "Renamer statistics"
- (getRnStats imp_decls ifaces) ;
+ ioToRnM ( dumpIfSet dump_rn "Renamer:"
+ (vcat (map ppr decls)) )
+ `thenRn_`
+
+ returnRn ()
- dumpIfSet dump_rn "Renamer:"
- (vcat (map ppr (local_decls ++ imp_decls)))
- }) `thenRn_`
+rnStats :: [RenamedHsDecl] -- Imported decls
+ -> RnMG ()
+rnStats imp_decls
+ = doptRn Opt_D_dump_rn_trace `thenRn` \ dump_rn_trace ->
+ doptRn Opt_D_dump_rn_stats `thenRn` \ dump_rn_stats ->
+ doptRn Opt_D_dump_rn `thenRn` \ dump_rn ->
+ getIfacesRn `thenRn` \ ifaces ->
+ ioToRnM (dumpIfSet (dump_rn_trace || dump_rn_stats || dump_rn)
+ "Renamer statistics"
+ (getRnStats imp_decls ifaces)) `thenRn_`
returnRn ()
\end{code}
%************************************************************************
\begin{code}
-dupFixityDecl rdr_name loc1 loc2
- = vcat [ptext SLIT("Multiple fixity declarations for") <+> quotes (ppr rdr_name),
- ptext SLIT("at ") <+> ppr loc1,
- ptext SLIT("and") <+> ppr loc2]
-
badDeprec d
= sep [ptext SLIT("Illegal deprecation when whole module is deprecated"),
nest 4 (ppr d)]
import RnTypes ( rnHsSigType, rnHsType )
import RnExpr ( rnMatch, rnGRHSs, rnPat, checkPrecMatch )
import RnEnv ( bindLocatedLocalsRn, lookupBndrRn, lookupInstDeclBndr,
- lookupSigOccRn, bindPatSigTyVars,
+ lookupSigOccRn, bindPatSigTyVars, extendNestedFixityEnv,
warnUnusedLocalBinds, mapFvRn, extendTyVarEnvFVRn,
)
import CmdLineOpts ( DynFlag(..) )
let
fixity_sigs = [(name,sig) | FixSig sig@(FixitySig name _ _) <- siglist ]
in
- extendFixityEnv fixity_sigs $
+ extendNestedFixityEnv fixity_sigs $
rn_mono_binds siglist mbinds `thenRn` \ (binds, bind_fvs) ->
#include "HsVersions.h"
-import {-# SOURCE #-} RnHiFiles
+import {-# SOURCE #-} RnHiFiles( loadInterface )
import FlattenInfo ( namesNeededForFlattening )
import HsSyn
-import RdrHsSyn ( RdrNameIE, RdrNameHsType, extractHsTyRdrTyVars )
+import RnHsSyn ( RenamedFixitySig )
+import RdrHsSyn ( RdrNameIE, RdrNameHsType, RdrNameFixitySig, extractHsTyRdrTyVars )
import RdrName ( RdrName, rdrNameModule, rdrNameOcc, isQual, isUnqual, isOrig,
- mkRdrUnqual, mkRdrQual,
+ mkRdrUnqual, mkRdrQual, setRdrNameOcc,
lookupRdrEnv, foldRdrEnv, rdrEnvToList, elemRdrEnv,
unqualifyRdrName
)
AvailInfo, Avails, GenAvailInfo(..), NameSupply(..),
ModIface(..), GhciMode(..),
Deprecations(..), lookupDeprec,
- extendLocalRdrEnv
+ extendLocalRdrEnv, lookupFixity
)
import RnMonad
import Name ( Name,
getSrcLoc, nameIsLocalOrFrom,
mkInternalName, mkExternalName,
mkIPName, nameOccName, nameModule_maybe,
- setNameModuleAndLoc
+ setNameModuleAndLoc, nameModule
)
import NameEnv
import NameSet
-import OccName ( OccName, occNameUserString, occNameFlavour )
+import OccName ( OccName, occNameUserString, occNameFlavour,
+ isDataSymOcc, setOccNameSpace, tcName )
import Module ( ModuleName, moduleName, mkVanillaModule,
mkSysModuleNameFS, moduleNameFS, WhereFrom(..) )
import PrelNames ( mkUnboundName,
import Outputable
import ListSetOps ( removeDups, equivClasses )
import Util ( sortLt )
-import BasicTypes ( mapIPName )
+import BasicTypes ( mapIPName, defaultFixity )
import List ( nub )
import UniqFM ( lookupWithDefaultUFM )
import Maybe ( mapMaybe )
+import Maybes ( orElse, catMaybes )
import CmdLineOpts
import FastString ( FastString )
\end{code}
Just name -> returnRn name
Nothing -> failWithRn (mkUnboundName rdr_name)
(unknownNameErr rdr_name)
- where
- lookup_local mod global_env rdr_name
- = case lookupRdrEnv global_env rdr_name of
+
+lookup_local mod global_env rdr_name
+ = case lookupRdrEnv global_env rdr_name of
Nothing -> Nothing
Just gres -> case [n | GRE n _ _ <- gres, nameIsLocalOrFrom mod n] of
[] -> Nothing
%*********************************************************
%* *
+\subsection{Looking up fixities}
+%* *
+%*********************************************************
+
+lookupFixity is a bit strange.
+
+* Nested local fixity decls are put in the local fixity env, which we
+ find with getFixtyEnv
+
+* Imported fixities are found in the HIT or PIT
+
+* Top-level fixity decls in this module may be for Names that are
+ either Global (constructors, class operations)
+ or Local/Exported (everything else)
+ (See notes with RnNames.getLocalDeclBinders for why we have this split.)
+ We put them all in the local fixity environment
+
+\begin{code}
+lookupFixityRn :: Name -> RnMS Fixity
+lookupFixityRn name
+ = getModuleRn `thenRn` \ this_mod ->
+ if nameIsLocalOrFrom this_mod name
+ then -- It's defined in this module
+ getFixityEnv `thenRn` \ local_fix_env ->
+ returnRn (lookupLocalFixity local_fix_env name)
+
+ else -- It's imported
+ -- For imported names, we have to get their fixities by doing a
+ -- loadHomeInterface, and consulting the Ifaces that comes back
+ -- from that, because the interface file for the Name might not
+ -- have been loaded yet. Why not? Suppose you import module A,
+ -- which exports a function 'f', thus;
+ -- module CurrentModule where
+ -- import A( f )
+ -- module A( f ) where
+ -- import B( f )
+ -- Then B isn't loaded right away (after all, it's possible that
+ -- nothing from B will be used). When we come across a use of
+ -- 'f', we need to know its fixity, and it's then, and only
+ -- then, that we load B.hi. That is what's happening here.
+ loadInterface doc name_mod ImportBySystem `thenRn` \ iface ->
+ returnRn (lookupFixity (mi_fixities iface) name)
+ where
+ doc = ptext SLIT("Checking fixity for") <+> ppr name
+ name_mod = moduleName (nameModule name)
+
+--------------------------------
+lookupLocalFixity :: LocalFixityEnv -> Name -> Fixity
+lookupLocalFixity env name
+ = case lookupNameEnv env name of
+ Just (FixitySig _ fix _) -> fix
+ Nothing -> defaultFixity
+
+extendNestedFixityEnv :: [(Name, RenamedFixitySig)] -> RnMS a -> RnMS a
+-- Used for nested fixity decls
+-- No need to worry about type constructors here,
+-- Should check for duplicates but we don't
+extendNestedFixityEnv fixes enclosed_scope
+ = getFixityEnv `thenRn` \ fix_env ->
+ let
+ new_fix_env = extendNameEnvList fix_env fixes
+ in
+ setFixityEnv new_fix_env enclosed_scope
+
+mkTopFixityEnv :: GlobalRdrEnv -> [RdrNameFixitySig] -> RnMG LocalFixityEnv
+mkTopFixityEnv gbl_env fix_sigs
+ = getModuleRn `thenRn` \ mod ->
+ let
+ -- GHC extension: look up both the tycon and data con
+ -- for con-like things
+ -- If neither are in scope, report an error; otherwise
+ -- add both to the fixity env
+ go fix_env (FixitySig rdr_name fixity loc)
+ = case catMaybes (map (lookup_local mod gbl_env) rdr_names) of
+ [] -> addErrRn (unknownNameErr rdr_name) `thenRn_`
+ returnRn fix_env
+ ns -> foldlRn add fix_env ns
+
+ where
+ add fix_env name
+ = case lookupNameEnv fix_env name of
+ Just (FixitySig _ _ loc') -> addErrRn (dupFixityDecl rdr_name loc loc') `thenRn_`
+ returnRn fix_env
+ Nothing -> returnRn (extendNameEnv fix_env name (FixitySig name fixity loc))
+
+ rdr_names | isDataSymOcc occ = [rdr_name, rdr_name_tc]
+ | otherwise = [rdr_name]
+
+ occ = rdrNameOcc rdr_name
+ rdr_name_tc = setRdrNameOcc rdr_name (setOccNameSpace occ tcName)
+ in
+ foldlRn go emptyLocalFixityEnv fix_sigs
+\end{code}
+
+
+%*********************************************************
+%* *
\subsection{Implicit free vars and sugar names}
%* *
%*********************************************************
addWarnRn (sep [ text (occNameFlavour (nameOccName name)) <+>
quotes (ppr name) <+> text "is deprecated:",
nest 4 (ppr txt) ])
+
+dupFixityDecl rdr_name loc1 loc2
+ = vcat [ptext SLIT("Multiple fixity declarations for") <+> quotes (ppr rdr_name),
+ ptext SLIT("at ") <+> ppr loc1,
+ ptext SLIT("and") <+> ppr loc2]
\end{code}
import RnHsSyn
import RnMonad
import RnEnv
-import RnTypes ( rnHsTypeFVs )
-import RnHiFiles ( lookupFixityRn )
+import RnTypes ( rnHsTypeFVs, precParseErr, sectionPrecErr )
import CmdLineOpts ( DynFlag(..), opt_IgnoreAsserts )
import Literal ( inIntRange, inCharRange )
import BasicTypes ( Fixity(..), FixityDirection(..), IPName(..),
- defaultFixity, negateFixity )
+ defaultFixity, negateFixity, compareFixity )
import PrelNames ( hasKey, assertIdKey,
eqClassName, foldrName, buildName, eqStringName,
cCallableClassName, cReturnableClassName,
rnRpats rpats `thenRn` \ (rpats', fvs) ->
returnRn (RecPatIn con' rpats', fvs `addOneFV` con')
-rnPat (TypePatIn name) =
- rnHsTypeFVs (text "type pattern") name `thenRn` \ (name', fvs) ->
+rnPat (TypePatIn name)
+ = rnHsTypeFVs (text "type pattern") name `thenRn` \ (name', fvs) ->
returnRn (TypePatIn name', fvs)
\end{code}
= rnHsTypeFVs doc a `thenRn` \ (t, fvT) ->
returnRn (HsType t, fvT)
where
- doc = text "renaming a type pattern"
+ doc = text "in a type argument"
rnExpr (ArithSeqIn seq)
= rn_seq seq `thenRn` \ (new_seq, fvs) ->
(pp_arg_op, arg_fix) section)
\end{code}
-Consider
-\begin{verbatim}
- a `op1` b `op2` c
-\end{verbatim}
-@(compareFixity op1 op2)@ tells which way to arrange appication, or
-whether there's an error.
-
-\begin{code}
-compareFixity :: Fixity -> Fixity
- -> (Bool, -- Error please
- Bool) -- Associate to the right: a op1 (b op2 c)
-compareFixity (Fixity prec1 dir1) (Fixity prec2 dir2)
- = case prec1 `compare` prec2 of
- GT -> left
- LT -> right
- EQ -> case (dir1, dir2) of
- (InfixR, InfixR) -> right
- (InfixL, InfixL) -> left
- _ -> error_please
- where
- right = (False, True)
- left = (False, False)
- error_please = (True, False)
-\end{code}
%************************************************************************
%* *
\begin{code}
ppr_op op = quotes (ppr op) -- Here, op can be a Name or a (Var n), where n is a Name
-ppr_opfix (pp_op, fixity) = pp_op <+> brackets (ppr fixity)
pp_prefix_minus = ptext SLIT("prefix `-'")
dupFieldErr str (dup:rest)
quotes (ppr dup),
ptext SLIT("in record"), text str]
-precParseErr op1 op2
- = hang (ptext SLIT("precedence parsing error"))
- 4 (hsep [ptext SLIT("cannot mix"), ppr_opfix op1, ptext SLIT("and"),
- ppr_opfix op2,
- ptext SLIT("in the same infix expression")])
-
-sectionPrecErr op arg_op section
- = vcat [ptext SLIT("The operator") <+> ppr_opfix op <+> ptext SLIT("of a section"),
- nest 4 (ptext SLIT("must have lower precedence than the operand") <+> ppr_opfix arg_op),
- nest 4 (ptext SLIT("in the section:") <+> quotes (ppr section))]
-
nonStdGuardErr guard
= hang (ptext
SLIT("accepting non-standard pattern guards (-fglasgow-exts to suppress this message)")
tryLoadInterface, loadOrphanModules,
loadExports, loadFixDecls, loadDeprecs,
- lookupFixityRn,
-
getTyClDeclBinders
) where
)
import RdrHsSyn ( RdrNameTyClDecl, RdrNameInstDecl, RdrNameRuleDecl )
import RnHsSyn ( extractHsTyNames_s )
-import BasicTypes ( Version, defaultFixity )
+import BasicTypes ( Version )
import RnTypes ( rnHsType )
import RnEnv
import RnMonad
import Module
import RdrName ( rdrNameOcc )
import SrcLoc ( mkSrcLoc )
-import Maybes ( maybeToBool, orElse )
+import Maybes ( maybeToBool )
import StringBuffer ( hGetStringBuffer )
import FastString ( mkFastString )
import ErrUtils ( Message )
\end{code}
%*********************************************************
-%* *
-\subsection{Looking up fixities}
-%* *
-%*********************************************************
-
-@lookupFixityRn@ has to be in RnIfaces (or RnHiFiles), instead of
-its obvious home in RnEnv, because it calls @loadHomeInterface@.
-
-lookupFixity is a bit strange.
-
-* Nested local fixity decls are put in the local fixity env, which we
- find with getFixtyEnv
-
-* Imported fixities are found in the HIT or PIT
-
-* Top-level fixity decls in this module may be for Names that are
- either Global (constructors, class operations)
- or Local/Exported (everything else)
- (See notes with RnNames.getLocalDeclBinders for why we have this split.)
- We put them all in the local fixity environment
-
-\begin{code}
-lookupFixityRn :: Name -> RnMS Fixity
-lookupFixityRn name
- = getModuleRn `thenRn` \ this_mod ->
- if nameIsLocalOrFrom this_mod name
- then -- It's defined in this module
- getFixityEnv `thenRn` \ local_fix_env ->
- returnRn (lookupLocalFixity local_fix_env name)
-
- else -- It's imported
- -- For imported names, we have to get their fixities by doing a
- -- loadHomeInterface, and consulting the Ifaces that comes back
- -- from that, because the interface file for the Name might not
- -- have been loaded yet. Why not? Suppose you import module A,
- -- which exports a function 'f', thus;
- -- module CurrentModule where
- -- import A( f )
- -- module A( f ) where
- -- import B( f )
- -- Then B isn't loaded right away (after all, it's possible that
- -- nothing from B will be used). When we come across a use of
- -- 'f', we need to know its fixity, and it's then, and only
- -- then, that we load B.hi. That is what's happening here.
- loadHomeInterface doc name `thenRn` \ iface ->
- returnRn (lookupNameEnv (mi_fixities iface) name `orElse` defaultFixity)
- where
- doc = ptext SLIT("Checking fixity for") <+> ppr name
-\end{code}
-
-
-%*********************************************************
%* *
\subsection{Errors}
%* *
get (HsFunTy ty1 ty2) = get ty1 `unionNameSets` get ty2
get (HsPredTy p) = extractHsPredTyNames p
get (HsOpTy ty1 tycon ty2) = get ty1 `unionNameSets` get ty2 `unionNameSets`
- unitNameSet tycon
+ case tycon of { HsTyOp n -> unitNameSet n ;
+ HsArrow -> emptyNameSet }
get (HsNumTy n) = emptyNameSet
get (HsTyVar tv) = unitNameSet tv
get (HsKindSig ty k) = get ty
isCmdLineMode _ = False
\end{code}
-%===================================================
-\subsubsection{ ENVIRONMENTS}
-%===================================================
-
\begin{code}
---------------------------------
type LocalFixityEnv = NameEnv RenamedFixitySig
-- We keep the whole fixity sig so that we
-- can report line-number info when there is a duplicate
emptyLocalFixityEnv :: LocalFixityEnv
emptyLocalFixityEnv = emptyNameEnv
-
-lookupLocalFixity :: LocalFixityEnv -> Name -> Fixity
-lookupLocalFixity env name
- = case lookupNameEnv env name of
- Just (FixitySig _ fix _) -> fix
- Nothing -> defaultFixity
\end{code}
+
%************************************************************************
%* *
\subsection{Interface file stuff}
getFixityEnv rn_down (SDown {rn_fixenv = fixity_env})
= return fixity_env
-extendFixityEnv :: [(Name, RenamedFixitySig)] -> RnMS a -> RnMS a
-extendFixityEnv fixes enclosed_scope
- rn_down l_down@(SDown {rn_fixenv = fixity_env})
- = let
- new_fixity_env = extendNameEnvList fixity_env fixes
- in
- enclosed_scope rn_down (l_down {rn_fixenv = new_fixity_env})
+setFixityEnv :: LocalFixityEnv -> RnMS a -> RnMS a
+setFixityEnv fixes enclosed_scope rn_down l_down
+ = enclosed_scope rn_down (l_down {rn_fixenv = fixes})
\end{code}
%================
\section[RnSource]{Main pass of renamer}
\begin{code}
-module RnTypes ( rnHsType, rnHsSigType, rnHsTypeFVs, rnHsSigTypeFVs, rnContext ) where
+module RnTypes ( rnHsType, rnHsSigType, rnHsTypeFVs, rnHsSigTypeFVs,
+ rnContext, precParseErr, sectionPrecErr ) where
-import CmdLineOpts ( DynFlag(Opt_WarnMisc, Opt_WarnUnusedMatches) )
+import CmdLineOpts ( DynFlag(Opt_WarnMisc, Opt_WarnUnusedMatches, Opt_GlasgowExts) )
import HsSyn
import RdrHsSyn ( RdrNameContext, RdrNameHsType, extractHsTyRdrTyVars, extractHsCtxtRdrTyVars )
import RnHsSyn ( RenamedContext, RenamedHsType, extractHsTyNames, tupleTyCon_name )
-import RnEnv ( lookupOccRn, newIPName, bindTyVarsRn )
+import RnEnv ( lookupOccRn, newIPName, bindTyVarsRn, lookupFixityRn )
import RnMonad
import PrelInfo ( cCallishClassKeys )
import NameSet ( FreeVars )
import Unique ( Uniquable(..) )
+import BasicTypes ( compareFixity, arrowFixity )
import List ( nub )
import ListSetOps ( removeDupsEq )
import Outputable
= lookupOccRn tyvar `thenRn` \ tyvar' ->
returnRn (HsTyVar tyvar')
-rnHsType doc (HsOpTy ty1 opname ty2)
- = lookupOccRn opname `thenRn` \ name' ->
- rnHsType doc ty1 `thenRn` \ ty1' ->
- rnHsType doc ty2 `thenRn` \ ty2' ->
- returnRn (HsOpTy ty1' name' ty2')
+rnHsType doc (HsOpTy ty1 op ty2)
+ = (case op of
+ HsArrow -> returnRn HsArrow
+ HsTyOp n -> lookupOccRn n `thenRn` \ n' ->
+ returnRn (HsTyOp n')
+ ) `thenRn` \ op' ->
+ rnHsType doc ty1 `thenRn` \ ty1' ->
+ rnHsType doc ty2 `thenRn` \ ty2' ->
+ lookupTyFixityRn op' `thenRn` \ fix ->
+ mkHsOpTyRn op' fix ty1' ty2'
+
rnHsType doc (HsNumTy i)
| i == 1 = returnRn (HsNumTy i)
rnHsTypes doc tys = mapRn (rnHsType doc) tys
\end{code}
+
\begin{code}
rnForAll doc forall_tyvars ctxt ty
= bindTyVarsRn doc forall_tyvars $ \ new_tyvars ->
returnRn (mkHsForAllTy (Just new_tyvars) new_ctxt new_ty)
\end{code}
+
+%*********************************************************
+%* *
+\subsection{Fixities}
+%* *
+%*********************************************************
+
+Infix types are read in a *right-associative* way, so that
+ a `op` b `op` c
+is always read in as
+ a `op` (b `op` c)
+
+mkHsOpTyRn rearranges where necessary. The two arguments
+have already been renamed and rearranged. It's made rather tiresome
+by the presence of ->
+
+\begin{code}
+lookupTyFixityRn HsArrow = returnRn arrowFixity
+lookupTyFixityRn (HsTyOp n)
+ = doptRn Opt_GlasgowExts `thenRn` \ glaExts ->
+ warnCheckRn glaExts (infixTyConWarn n) `thenRn_`
+ lookupFixityRn n
+
+-- Building (ty1 `op1` (ty21 `op2` ty22))
+mkHsOpTyRn :: HsTyOp Name -> Fixity
+ -> RenamedHsType -> RenamedHsType
+ -> RnMS RenamedHsType
+
+mkHsOpTyRn op1 fix1 ty1 ty2@(HsOpTy ty21 op2 ty22)
+ = lookupTyFixityRn op2 `thenRn` \ fix2 ->
+ let
+ (nofix_error, associate_right) = compareFixity fix1 fix2
+ in
+ if nofix_error then
+ addErrRn (precParseErr (quotes (ppr op1),fix1)
+ (quotes (ppr op2),fix2)) `thenRn_`
+ returnRn (HsOpTy ty1 op1 ty2)
+ else
+ if not associate_right then
+ -- Rearrange to ((ty1 `op1` ty21) `op2` ty22)
+ mkHsOpTyRn op1 fix1 ty1 ty21 `thenRn` \ new_ty ->
+ returnRn (HsOpTy new_ty op2 ty22)
+ else
+ returnRn (HsOpTy ty1 op1 ty2)
+
+mkHsOpTyRn op fix ty1 ty2 -- Default case, no rearrangment
+ = ASSERT( not_op_ty ty1 )
+ returnRn (HsOpTy ty1 op ty2)
+
+mkHsFunTyRn ty1 ty2 -- Precedence of function arrow is 0
+ = returnRn (HsFunTy ty1 ty2) -- so no rearrangement reqd. Change
+ -- this if fixity of -> increases.
+
+not_op_ty (HsOpTy _ _ _) = False
+not_op_ty other = True
+\end{code}
+
+%*********************************************************
+%* *
+\subsection{Contexts and predicates}
+%* *
+%*********************************************************
+
\begin{code}
rnContext :: SDoc -> RdrNameContext -> RnMS RenamedContext
rnContext doc ctxt
returnRn (HsIParam name ty')
\end{code}
+
+%*********************************************************
+%* *
+\subsection{Errors}
+%* *
+%*********************************************************
+
\end{code}
\begin{code}
forAllWarn doc ty tyvar
naughtyCCallContextErr (HsClassP clas _)
= sep [ptext SLIT("Can't use class") <+> quotes (ppr clas),
ptext SLIT("in a context")]
+
+precParseErr op1 op2
+ = hang (ptext SLIT("precedence parsing error"))
+ 4 (hsep [ptext SLIT("cannot mix"), ppr_opfix op1, ptext SLIT("and"),
+ ppr_opfix op2,
+ ptext SLIT("in the same infix expression")])
+
+sectionPrecErr op arg_op section
+ = vcat [ptext SLIT("The operator") <+> ppr_opfix op <+> ptext SLIT("of a section"),
+ nest 4 (ptext SLIT("must have lower precedence than the operand") <+> ppr_opfix arg_op),
+ nest 4 (ptext SLIT("in the section:") <+> quotes (ppr section))]
+
+infixTyConWarn op
+ = ftext FSLIT("Accepting non-standard infix type constructor") <+> quotes (ppr op)
+
+ppr_opfix (pp_op, fixity) = pp_op <+> brackets (ppr fixity)
\end{code}
\ No newline at end of file
#include "HsVersions.h"
-import HsSyn ( HsType(..), HsTyVarBndr(..),
+import HsSyn ( HsType(..), HsTyVarBndr(..), HsTyOp(..),
Sig(..), HsPred(..), pprParendHsType, HsTupCon(..), hsTyVarNames )
import RnHsSyn ( RenamedHsType, RenamedHsPred, RenamedContext, RenamedSig, extractHsTyVars )
import TcHsSyn ( TcId )
kcTypeType ty2 `thenTc_`
returnTc liftedTypeKind
-kcHsType (HsNumTy _) -- The unit type for generics
- = returnTc liftedTypeKind
+kcHsType (HsOpTy ty1 HsArrow ty2)
+ = kcTypeType ty1 `thenTc_`
+ kcTypeType ty2 `thenTc_`
+ returnTc liftedTypeKind
-kcHsType ty@(HsOpTy ty1 op ty2)
+kcHsType ty@(HsOpTy ty1 (HsTyOp op) ty2)
= kcTyVar op `thenTc` \ op_kind ->
kcHsType ty1 `thenTc` \ ty1_kind ->
kcHsType ty2 `thenTc` \ ty2_kind ->
kcAppKind op_kind ty1_kind `thenTc` \ op_kind' ->
kcAppKind op_kind' ty2_kind
+kcHsType (HsNumTy _) -- The unit type for generics
+ = returnTc liftedTypeKind
+
kcHsType (HsPredTy pred)
= kcHsPred pred `thenTc_`
returnTc liftedTypeKind
tc_type ty2 `thenTc` \ tau_ty2 ->
returnTc (mkFunTy tau_ty1 tau_ty2)
-tc_type (HsNumTy n)
- = ASSERT(n== 1)
- returnTc (mkTyConApp genUnitTyCon [])
+tc_type (HsOpTy ty1 HsArrow ty2)
+ = tc_type ty1 `thenTc` \ tau_ty1 ->
+ tc_type ty2 `thenTc` \ tau_ty2 ->
+ returnTc (mkFunTy tau_ty1 tau_ty2)
-tc_type (HsOpTy ty1 op ty2)
+tc_type (HsOpTy ty1 (HsTyOp op) ty2)
= tc_type ty1 `thenTc` \ tau_ty1 ->
tc_type ty2 `thenTc` \ tau_ty2 ->
tc_fun_type op [tau_ty1,tau_ty2]
+tc_type (HsNumTy n)
+ = ASSERT(n== 1)
+ returnTc (mkTyConApp genUnitTyCon [])
+
tc_type (HsAppTy ty1 ty2) = tc_app ty1 [ty2]
tc_type (HsPredTy pred)
Nevertheless, they can be useful when defining "phantom types".</para>
</sect2>
+<sect2 id="infix-tycons">
+<title>Infix type constructors</title>
+
+<para>
+GHC allows type constructors to be operators, and to be written infix, very much
+like expressions. More specifically:
+<itemizedlist>
+<listitem><para>
+ A type constructor can be an operator, beginning with a colon; e.g. <literal>:*:</literal>.
+ The lexical syntax is the same as that for data constructors.
+ </para></listitem>
+<listitem><para>
+ Types can be written infix. For example <literal>Int :*: Bool</literal>.
+ </para></listitem>
+<listitem><para>
+ Back-quotes work
+ as for expressions, both for type constructors and type variables; e.g. <literal>Int `Either` Bool</literal>, or
+ <literal>Int `a` Bool</literal>. Similarly, parentheses work the same; e.g. <literal>(:*:) Int Bool</literal>.
+ </para></listitem>
+<listitem><para>
+ Fixities may be declared for type constructors just as for data constructors. However,
+ one cannot distinguish between the two in a fixity declaration; a fixity declaration
+ sets the fixity for a data constructor and the corresponding type constructor. For example:
+<screen>
+ infixl 7 T, :*:
+</screen>
+ sets the fixity for both type constructor <literal>T</literal> and data constructor <literal>T</literal>,
+ and similarly for <literal>:*:</literal>.
+ <literal>Int `a` Bool</literal>.
+ </para></listitem>
+<listitem><para>
+ Function arrow is <literal>infixr</literal> with fixity 0. (This might change; I'm not sure what it should be.)
+ </para></listitem>
+<listitem><para>
+ Data type and type-synonym declarations can be written infix. E.g.
+<screen>
+ data a :*: b = Foo a b
+ type a :+: b = Either a b
+</screen>
+ </para></listitem>
+<listitem><para>
+ The only thing that differs between operators in types and operators in expressions is that
+ ordinary non-constructor operators, such as <literal>+</literal> and <literal>*</literal>
+ are not allowed in types. Reason: the uniform thing to do would be to make them type
+ variables, but that's not very useful. A less uniform but more useful thing would be to
+ allow them to be type <emphasis>constructors</emphasis>. But that gives trouble in export
+ lists. So for now we just exclude them.
+ </para></listitem>
+
+</itemizedlist>
+</para>
+</sect2>
+
<sect2 id="class-method-types">
<title>Class method types
</title>
</sect2>
<sect2 id="scoped-type-variables">
-<title>Scoped Type Variables
+<title>Scoped type variables
</title>
<para>
<para>Glasgow Haskell is a changing system so there are sure to be
bugs in it. </para>
- <para>To repot a bug, either:</para>
+ <para>To report a bug, either:</para>
<itemizedlist>
<listitem>
projects / ghc-hetmet.git / commitdiff