\begin{code}
module TcTyClsDecls (
- tcTyAndClassDecls, tcFamInstDecl, mkAuxBinds
+ tcTyAndClassDecls, tcFamInstDecl, mkRecSelBinds
) where
#include "HsVersions.h"
import TyCon
import DataCon
import Id
-import MkId ( rEC_SEL_ERROR_ID )
+import MkId ( mkDefaultMethodId )
+import MkCore ( rEC_SEL_ERROR_ID )
import IdInfo
import Var
import VarSet
tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
-> TcM (TcGblEnv, -- Input env extended by types and classes
-- and their implicit Ids,DataCons
- HsValBinds Name) -- Renamed bindings for record selectors
+ HsValBinds Name, -- Renamed bindings for record selectors
+ [Id]) -- Default method ids
+
-- Fails if there are any errors
tcTyAndClassDecls boot_details allDecls
-- See notes with checkCycleErrs
; checkCycleErrs decls
; mod <- getModule
- ; traceTc (text "tcTyAndCl" <+> ppr mod)
+ ; traceTc "tcTyAndCl" (ppr mod)
; (syn_tycons, alg_tyclss) <- fixM (\ ~(_rec_syn_tycons, rec_alg_tyclss) ->
do { let { -- Seperate ordinary synonyms from all other type and
-- class declarations and add all associated type
; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
-- Perform the validity check
- { traceTc (text "ready for validity check")
+ { traceTc "ready for validity check" empty
; mapM_ (addLocM checkValidTyCl) decls
- ; traceTc (text "done")
+ ; traceTc "done" empty
-- Add the implicit things;
-- we want them in the environment because
-- second time here. This doesn't matter as the definitions are
-- the same.
; let { implicit_things = concatMap implicitTyThings alg_tyclss
- ; aux_binds = mkAuxBinds alg_tyclss }
- ; traceTc ((text "Adding" <+> ppr alg_tyclss)
- $$ (text "and" <+> ppr implicit_things))
+ ; rec_sel_binds = mkRecSelBinds alg_tyclss
+ ; dm_ids = mkDefaultMethodIds alg_tyclss }
+ ; traceTc "Adding types and classes" $ vcat
+ [ ppr alg_tyclss
+ , text "and" <+> ppr implicit_things ]
; env <- tcExtendGlobalEnv implicit_things getGblEnv
- ; return (env, aux_binds) }
+ ; return (env, rec_sel_binds, dm_ids) }
}
where
-- Pull associated types out of class declarations, to tie them into the
GADTs).
\begin{code}
-tcFamInstDecl :: LTyClDecl Name -> TcM TyThing
-tcFamInstDecl (L loc decl)
+tcFamInstDecl :: TopLevelFlag -> LTyClDecl Name -> TcM TyThing
+tcFamInstDecl top_lvl (L loc decl)
= -- Prime error recovery, set source location
setSrcSpan loc $
tcAddDeclCtxt decl $
; tc <- tcFamInstDecl1 decl
; checkValidTyCon tc -- Remember to check validity;
-- no recursion to worry about here
+
+ -- Check that toplevel type instances are not for associated types.
+ ; when (isTopLevel top_lvl && isAssocFamily tc)
+ (addErr $ assocInClassErr (tcdName decl))
+
; return (ATyCon tc) }
+isAssocFamily :: TyCon -> Bool -- Is an assocaited type
+isAssocFamily tycon
+ = case tyConFamInst_maybe tycon of
+ Nothing -> panic "isAssocFamily: no family?!?"
+ Just (fam, _) -> isTyConAssoc fam
+
+assocInClassErr :: Name -> SDoc
+assocInClassErr name
+ = ptext (sLit "Associated type") <+> quotes (ppr name) <+>
+ ptext (sLit "must be inside a class instance")
+
+
+
tcFamInstDecl1 :: TyClDecl Name -> TcM TyCon
-- "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
- checkTc (isOpenTyCon family) (notFamily family)
+ checkTc (isFamilyTyCon family) (notFamily family)
; checkTc (isSynTyCon family) (wrongKindOfFamily family)
; -- (1) kind check the right-hand side of the type equation
-- (4) construct representation tycon
; rep_tc_name <- newFamInstTyConName tc_name t_typats loc
; buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs)
- (typeKind t_rhs) (Just (family, t_typats))
+ (typeKind t_rhs)
+ NoParentTyCon (Just (family, t_typats))
}}
-- "newtype instance" and "data instance"
tcdCons = cons})
= kcIdxTyPats decl $ \k_tvs k_typats resKind fam_tycon ->
do { -- check that the family declaration is for the right kind
- checkTc (isOpenTyCon fam_tycon) (notFamily fam_tycon)
+ checkTc (isFamilyTyCon fam_tycon) (notFamily fam_tycon)
; checkTc (isAlgTyCon fam_tycon) (wrongKindOfFamily fam_tycon)
; -- (1) kind check the data declaration as usual
NewType -> ASSERT( not (null data_cons) )
mkNewTyConRhs rep_tc_name rep_tycon (head data_cons)
; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
- False h98_syntax (Just (fam_tycon, t_typats))
+ False h98_syntax NoParentTyCon (Just (fam_tycon, t_typats))
-- We always assume that indexed types are recursive. Why?
-- (1) Due to their open nature, we can never be sure that a
-- further instance might not introduce a new recursive
kcSynDecl (AcyclicSCC (L loc decl))
= tcAddDeclCtxt decl $
kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
- do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
+ do { traceTc "kcd1" (ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
<+> brackets (ppr k_tvs))
; (k_rhs, rhs_kind) <- kcLHsType (tcdSynRhs decl)
- ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
+ ; traceTc "kcd2" (ppr (unLoc (tcdLName decl)))
; let tc_kind = foldr (mkArrowKind . hsTyVarKind . unLoc) rhs_kind k_tvs
; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
(unLoc (tcdLName decl), tc_kind)) })
tcSynDecl
(TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
= tcTyVarBndrs tvs $ \ tvs' -> do
- { traceTc (text "tcd1" <+> ppr tc_name)
+ { traceTc "tcd1" (ppr tc_name)
; rhs_ty' <- tcHsKindedType rhs_ty
; tycon <- buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty')
- (typeKind rhs_ty') Nothing
+ (typeKind rhs_ty') NoParentTyCon Nothing
; return (ATyCon tycon)
}
tcSynDecl d = pprPanic "tcSynDecl" (ppr d)
tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
tcTyClDecl calc_isrec decl
- = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
+ = tcAddDeclCtxt decl (tcTyClDecl1 NoParentTyCon calc_isrec decl)
-- "type family" declarations
-tcTyClDecl1 :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
-tcTyClDecl1 _calc_isrec
+tcTyClDecl1 :: TyConParent -> (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
+tcTyClDecl1 parent _calc_isrec
(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)
+ { traceTc "type family:" (ppr tc_name)
-- Check that we don't use families without -XTypeFamilies
; idx_tys <- doptM Opt_TypeFamilies
; checkTc idx_tys $ badFamInstDecl tc_name
- ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) kind Nothing
+ ; tycon <- buildSynTyCon tc_name tvs' SynFamilyTyCon kind parent Nothing
; return [ATyCon tycon]
}
-- "data family" declaration
-tcTyClDecl1 _calc_isrec
+tcTyClDecl1 parent _calc_isrec
(TyFamily {tcdFlavour = DataFamily,
tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = mb_kind})
= tcTyVarBndrs tvs $ \ tvs' -> do
- { traceTc (text "data family: " <+> ppr tc_name)
+ { traceTc "data family:" (ppr tc_name)
; extra_tvs <- tcDataKindSig mb_kind
; let final_tvs = tvs' ++ extra_tvs -- we may not need these
; checkTc idx_tys $ badFamInstDecl tc_name
; tycon <- buildAlgTyCon tc_name final_tvs []
- mkOpenDataTyConRhs Recursive False True Nothing
+ DataFamilyTyCon Recursive False True
+ parent Nothing
; return [ATyCon tycon]
}
-- "newtype" and "data"
-- NB: not used for newtype/data instances (whether associated or not)
-tcTyClDecl1 calc_isrec
+tcTyClDecl1 parent calc_isrec
(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
= tcTyVarBndrs tvs $ \ tvs' -> do
NewType -> 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
+ (want_generic && canDoGenerics data_cons) (not h98_syntax)
+ parent Nothing
})
; return [ATyCon tycon]
}
is_rec = calc_isrec tc_name
h98_syntax = consUseH98Syntax cons
-tcTyClDecl1 calc_isrec
+tcTyClDecl1 _parent calc_isrec
(ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
tcdCtxt = ctxt, tcdMeths = meths,
tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
= tcTyVarBndrs tvs $ \ tvs' -> do
{ ctxt' <- tcHsKindedContext ctxt
; fds' <- mapM (addLocM tc_fundep) fundeps
- ; atss <- mapM (addLocM (tcTyClDecl1 (const Recursive))) ats
- -- NB: 'ats' only contains "type family" and "data family"
- -- declarations as well as type family defaults
- ; let ats' = map (setAssocFamilyPermutation tvs') (concat atss)
; sig_stuff <- tcClassSigs class_name sigs meths
- ; clas <- fixM (\ clas ->
- let -- This little knot is just so we can get
+ ; clas <- fixM $ \ clas -> do
+ { let -- This little knot is just so we can get
-- hold of the name of the class TyCon, which we
-- need to look up its recursiveness
tycon_name = tyConName (classTyCon clas)
tc_isrec = calc_isrec tycon_name
- in
- buildClass False {- Must include unfoldings for selectors -}
- class_name tvs' ctxt' fds' ats'
- sig_stuff tc_isrec)
- ; return (AClass clas : ats')
+ ; atss' <- mapM (addLocM $ tcTyClDecl1 (AssocFamilyTyCon clas) (const Recursive)) ats
+ -- NB: 'ats' only contains "type family" and "data family"
+ -- declarations as well as type family defaults
+ ; buildClass False {- Must include unfoldings for selectors -}
+ class_name tvs' ctxt' fds' (concat atss')
+ sig_stuff tc_isrec }
+ ; return (AClass clas : map ATyCon (classATs clas))
-- NB: Order is important due to the call to `mkGlobalThings' when
-- tying the the type and class declaration type checking knot.
}
; tvs2' <- mapM tcLookupTyVar tvs2 ;
; return (tvs1', tvs2') }
-tcTyClDecl1 _
+tcTyClDecl1 _ _
(ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
= return [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
-tcTyClDecl1 _ d = pprPanic "tcTyClDecl1" (ppr d)
+tcTyClDecl1 _ _ d = pprPanic "tcTyClDecl1" (ppr d)
-----------------------------------
tcConDecls :: Bool -> Bool -> TyCon -> ([TyVar], Type)
checkValidTyCl decl
= tcAddDeclCtxt decl $
do { thing <- tcLookupLocatedGlobal (tcdLName decl)
- ; traceTc (text "Validity of" <+> ppr thing)
+ ; traceTc "Validity of" (ppr thing)
; case thing of
ATyCon tc -> checkValidTyCon tc
AClass cl -> checkValidClass cl
_ -> panic "checkValidTyCl"
- ; traceTc (text "Done validity of" <+> ppr thing)
+ ; traceTc "Done validity of" (ppr thing)
}
-------------------------
checkValidTyCon tc
| isSynTyCon tc
= case synTyConRhs tc of
- OpenSynTyCon _ _ -> return ()
- SynonymTyCon ty -> checkValidType syn_ctxt ty
+ SynFamilyTyCon {} -> return ()
+ SynonymTyCon ty -> checkValidType syn_ctxt ty
| otherwise
= do -- Check the context on the data decl
checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc)
checkValidDataCon tc con
= setSrcSpan (srcLocSpan (getSrcLoc con)) $
addErrCtxt (dataConCtxt con) $
- do { traceTc (ptext (sLit "Validity of data con") <+> ppr con)
+ do { traceTc "Validity of data con" (ppr con)
; let tc_tvs = tyConTyVars tc
res_ty_tmpl = mkFamilyTyConApp tc (mkTyVarTys tc_tvs)
actual_res_ty = dataConOrigResTy con
-- 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)
+ ; traceTc "class op type" (ppr op_ty <+> ppr tau)
; checkValidType (FunSigCtxt op_name) tau
-- Check that the type mentions at least one of
%************************************************************************
\begin{code}
-mkAuxBinds :: [TyThing] -> HsValBinds Name
+mkDefaultMethodIds :: [TyThing] -> [Id]
+-- See Note [Default method Ids and Template Haskell]
+mkDefaultMethodIds things
+ = [ mkDefaultMethodId sel_id dm_name
+ | AClass cls <- things
+ , (sel_id, DefMeth dm_name) <- classOpItems cls ]
+\end{code}
+
+Note [Default method Ids and Template Haskell]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider this (Trac #4169):
+ class Numeric a where
+ fromIntegerNum :: a
+ fromIntegerNum = ...
+
+ ast :: Q [Dec]
+ ast = [d| instance Numeric Int |]
+
+When we typecheck 'ast' we have done the first pass over the class decl
+(in tcTyClDecls), but we have not yet typechecked the default-method
+declarations (becuase they can mention value declarations). So we
+must bring the default method Ids into scope first (so they can be seen
+when typechecking the [d| .. |] quote, and typecheck them later.
+
+\begin{code}
+mkRecSelBinds :: [TyThing] -> HsValBinds Name
-- NB We produce *un-typechecked* bindings, rather like 'deriving'
-- This makes life easier, because the later type checking will add
-- all necessary type abstractions and applications
-mkAuxBinds ty_things
+mkRecSelBinds ty_things
= ValBindsOut [(NonRecursive, b) | b <- binds] sigs
where
(sigs, binds) = unzip rec_sels
badGenericMethodType :: Name -> Kind -> SDoc
badGenericMethodType op op_ty
= hang (ptext (sLit "Generic method type is too complex"))
- 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
+ 2 (vcat [ppr op <+> dcolon <+> ppr op_ty,
ptext (sLit "You can only use type variables, arrows, lists, and tuples")])
recSynErr :: [LTyClDecl Name] -> TcRn ()
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