\begin{code}
module TcClassDcl ( tcClassSigs, tcClassDecl2,
findMethodBind, instantiateMethod, tcInstanceMethodBody,
- mkGenericDefMethBind, getGenericInstances,
+ mkGenericDefMethBind,
tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn
) where
#include "HsVersions.h"
import HsSyn
-import RnHsSyn
-import Inst
-import InstEnv
import TcEnv
import TcPat( addInlinePrags )
import TcBinds
import TcType
import TcRnMonad
import BuildTyCl( TcMethInfo )
-import Generics
import Class
-import TyCon
-import MkId
import Id
import Name
import Var
-import NameSet
import Outputable
-import PrelNames
import DynFlags
import ErrUtils
-import Util
-import ListSetOps
import SrcLoc
import Maybes
import BasicTypes
import FastString
import Control.Monad
-import Data.List
\end{code}
-- (If necessary we can fix that, but we don't have a convenient Id to hand.)
tcDefMeth clas tyvars this_dict binds_in sigs sig_fn prag_fn (sel_id, dm_info)
= case dm_info of
- NoDefMeth -> return emptyBag
+ NoDefMeth -> do { mapM_ (addLocM (badDmPrag sel_id)) prags
+ ; return emptyBag }
DefMeth dm_name -> tc_dm dm_name (instantiateMethod clas sel_id (mkTyVarTys tyvars))
GenDefMeth dm_name -> do { tau <- tc_genop_ty (findGenericSig sigs sel_name)
; tc_dm dm_name tau }
-- In the case of a generic default, we have to get the type from the signature
-- Otherwise we can get it by instantiating the method selector
where
- sel_name = idName sel_id
+ sel_name = idName sel_id
+ prags = prag_fn sel_name
+ dm_sig_fn _ = sig_fn sel_name
+ dm_bind = findMethodBind sel_name binds_in
+ `orElse` pprPanic "tcDefMeth" (ppr sel_id)
-- Eg. class C a where
-- op :: forall b. Eq b => a -> [b] -> a
-- Base the local_dm_name on the selector name, because
-- type errors from tcInstanceMethodBody come from here
- ; let meth_bind = findMethodBind sel_name binds_in
- `orElse` pprPanic "tcDefMeth" (ppr sel_id)
-
- dm_sig_fn _ = sig_fn sel_name
- prags = prag_fn sel_name
-
- dm_ty = mkSigmaTy tyvars [mkClassPred clas (mkTyVarTys tyvars)] local_dm_ty
+ ; let dm_ty = mkSigmaTy tyvars [mkClassPred clas (mkTyVarTys tyvars)] local_dm_ty
dm_id = mkExportedLocalId dm_name dm_ty
local_dm_id = mkLocalId local_dm_name local_dm_ty
(ptext (sLit "Ignoring SPECIALISE pragmas on default method")
<+> quotes (ppr sel_name))
- ; dm_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict]
+ ; tc_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict]
dm_id_w_inline local_dm_id dm_sig_fn
- IsDefaultMethod meth_bind
+ IsDefaultMethod dm_bind
- ; return (unitBag dm_bind) }
+ ; return (unitBag tc_bind) }
tc_genop_ty :: LHsType Name -> TcM Type
tc_genop_ty hs_ty
[mkSimpleMatch [] rhs]) }
where
rhs = nlHsVar dm_name
-
----------------------------
-getGenericInstances :: [LTyClDecl Name] -> TcM [InstInfo Name]
-getGenericInstances class_decls
- = do { gen_inst_infos <- mapM (addLocM get_generics) class_decls
- ; let { gen_inst_info = concat gen_inst_infos }
-
- -- Return right away if there is no generic stuff
- ; if null gen_inst_info then return []
- else do
-
- -- Otherwise print it out
- { dumpDerivingInfo $ hang (ptext (sLit "Generic instances"))
- 2 (vcat (map pprInstInfoDetails gen_inst_info))
- ; return gen_inst_info }}
-
-get_generics :: TyClDecl Name -> TcM [InstInfo Name]
-get_generics decl@(ClassDecl {tcdLName = class_name, tcdMeths = def_methods})
- | null generic_binds
- = return [] -- The comon case: no generic default methods
-
- | otherwise -- A source class decl with generic default methods
- = recoverM (return []) $
- tcAddDeclCtxt decl $ do
- clas <- tcLookupLocatedClass class_name
-
- -- Group by type, and
- -- make an InstInfo out of each group
- let
- groups = groupWith listToBag generic_binds
-
- inst_infos <- mapM (mkGenericInstance clas) groups
-
- -- Check that there is only one InstInfo for each type constructor
- -- The main way this can fail is if you write
- -- f {| a+b |} ... = ...
- -- f {| x+y |} ... = ...
- -- Then at this point we'll have an InstInfo for each
- --
- -- The class should be unary, which is why simpleInstInfoTyCon should be ok
- let
- tc_inst_infos :: [(TyCon, InstInfo Name)]
- tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos]
-
- bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos,
- group `lengthExceeds` 1]
- get_uniq (tc,_) = getUnique tc
-
- mapM_ (addErrTc . dupGenericInsts) bad_groups
-
- -- Check that there is an InstInfo for each generic type constructor
- let
- missing = genericTyConNames `minusList` [tyConName tc | (tc,_) <- tc_inst_infos]
-
- checkTc (null missing) (missingGenericInstances missing)
-
- return inst_infos
- where
- generic_binds :: [(HsType Name, LHsBind Name)]
- generic_binds = getGenericBinds def_methods
-get_generics decl = pprPanic "get_generics" (ppr decl)
-
-
----------------------------------
-getGenericBinds :: LHsBinds Name -> [(HsType Name, LHsBind Name)]
- -- Takes a group of method bindings, finds the generic ones, and returns
- -- them in finite map indexed by the type parameter in the definition.
-getGenericBinds binds = concat (map getGenericBind (bagToList binds))
-
-getGenericBind :: LHsBindLR Name Name -> [(HsType Name, LHsBindLR Name Name)]
-getGenericBind (L loc bind@(FunBind { fun_matches = MatchGroup matches ty }))
- = groupWith wrap (mapCatMaybes maybeGenericMatch matches)
- where
- wrap ms = L loc (bind { fun_matches = MatchGroup ms ty })
-getGenericBind _
- = []
-
-groupWith :: ([a] -> b) -> [(HsType Name, a)] -> [(HsType Name, b)]
-groupWith _ [] = []
-groupWith op ((t,v):prs) = (t, op (v:vs)) : groupWith op rest
- where
- vs = map snd this
- (this,rest) = partition same_t prs
- same_t (t', _v) = t `eqPatType` t'
-
-eqPatLType :: LHsType Name -> LHsType Name -> Bool
-eqPatLType t1 t2 = unLoc t1 `eqPatType` unLoc t2
-
-eqPatType :: HsType Name -> HsType Name -> Bool
--- A very simple equality function, only for
--- type patterns in generic function definitions.
-eqPatType (HsTyVar v1) (HsTyVar v2) = v1==v2
-eqPatType (HsAppTy s1 t1) (HsAppTy s2 t2) = s1 `eqPatLType` s2 && t1 `eqPatLType` t2
-eqPatType (HsOpTy s1 op1 t1) (HsOpTy s2 op2 t2) = s1 `eqPatLType` s2 && t1 `eqPatLType` t2 && unLoc op1 == unLoc op2
-eqPatType (HsNumTy n1) (HsNumTy n2) = n1 == n2
-eqPatType (HsParTy t1) t2 = unLoc t1 `eqPatType` t2
-eqPatType t1 (HsParTy t2) = t1 `eqPatType` unLoc t2
-eqPatType _ _ = False
-
----------------------------------
-mkGenericInstance :: Class
- -> (HsType Name, LHsBinds Name)
- -> TcM (InstInfo Name)
-
-mkGenericInstance clas (hs_ty, binds) = do
- -- Make a generic instance declaration
- -- For example: instance (C a, C b) => C (a+b) where { binds }
-
- -- Extract the universally quantified type variables
- -- and wrap them as forall'd tyvars, so that kind inference
- -- works in the standard way
- let
- sig_tvs = userHsTyVarBndrs $ map noLoc $ nameSetToList $
- extractHsTyVars (noLoc hs_ty)
- hs_forall_ty = noLoc $ mkExplicitHsForAllTy sig_tvs (noLoc []) (noLoc hs_ty)
-
- -- Type-check the instance type, and check its form
- forall_inst_ty <- tcHsSigType GenPatCtxt hs_forall_ty
- let
- (tyvars, inst_ty) = tcSplitForAllTys forall_inst_ty
-
- checkTc (validGenericInstanceType inst_ty)
- (badGenericInstanceType binds)
-
- -- Make the dictionary function.
- span <- getSrcSpanM
- overlap_flag <- getOverlapFlag
- dfun_name <- newDFunName clas [inst_ty] span
- let
- inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
- dfun_id = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty]
- ispec = mkLocalInstance dfun_id overlap_flag
-
- return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] False })
\end{code}
-
%************************************************************************
%* *
Error messages
omittedATWarn :: Name -> SDoc
omittedATWarn at
= ptext (sLit "No explicit AT declaration for") <+> quotes (ppr at)
-
+{-
badGenericInstanceType :: LHsBinds Name -> SDoc
badGenericInstanceType binds
= vcat [ptext (sLit "Illegal type pattern in the generic bindings"),
]
where
ppr_inst_ty (_,inst) = ppr (simpleInstInfoTy inst)
+-}
+badDmPrag :: Id -> Sig Name -> TcM ()
+badDmPrag sel_id prag
+ = addErrTc (ptext (sLit "The") <+> hsSigDoc prag <+> ptext (sLit "for default method")
+ <+> quotes (ppr sel_id)
+ <+> ptext (sLit "lacks an accompanying binding"))
\end{code}
projects / ghc-hetmet.git / blobdiff