X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcInstDcls.lhs;h=ac5c89667afc77bb522945b7ff5ef9c90972442e;hp=1be9ffc8b8c8b80e9768d0632cb010306f109f0f;hb=ab22f4e6456820c1b5169d75f5975a94e61f54ce;hpb=171d4582f4b9a8e0f11f8738079accbb22bafdcb diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs index 1be9ffc..ac5c896 100644 --- a/compiler/typecheck/TcInstDcls.lhs +++ b/compiler/typecheck/TcInstDcls.lhs @@ -1,7 +1,9 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % -\section[TcInstDecls]{Typechecking instance declarations} + +TcInstDecls: Typechecking instance declarations \begin{code} module TcInstDcls ( tcInstDecls1, tcInstDecls2 ) where @@ -9,56 +11,43 @@ module TcInstDcls ( tcInstDecls1, tcInstDecls2 ) where #include "HsVersions.h" import HsSyn -import TcBinds ( mkPragFun, tcPrags, badBootDeclErr ) -import TcTyClsDecls ( tcIdxTyInstDecl ) -import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr, badATErr, - omittedATWarn, tcClassDecl2, getGenericInstances ) +import TcBinds +import TcTyClsDecls +import TcClassDcl import TcRnMonad -import TcMType ( tcSkolSigType, checkValidInstance, - checkValidInstHead ) -import TcType ( TcType, mkClassPred, tcSplitSigmaTy, - tcSplitDFunHead, SkolemInfo(InstSkol), - tcSplitTyConApp, - tcSplitDFunTy, mkFunTy ) -import Inst ( newDictBndr, newDictBndrs, instToId, showLIE, - getOverlapFlag, tcExtendLocalInstEnv ) -import InstEnv ( mkLocalInstance, instanceDFunId ) -import FamInst ( tcExtendLocalFamInstEnv ) -import FamInstEnv ( extractFamInsts ) -import TcDeriv ( tcDeriving ) -import TcEnv ( InstInfo(..), InstBindings(..), - newDFunName, tcExtendIdEnv, tcExtendGlobalEnv - ) -import TcHsType ( kcHsSigType, tcHsKindedType ) -import TcUnify ( checkSigTyVars ) -import TcSimplify ( tcSimplifySuperClasses ) -import Type ( zipOpenTvSubst, substTheta, mkTyConApp, mkTyVarTy, - TyThing(ATyCon), isTyVarTy, tcEqType, - substTys, emptyTvSubst, extendTvSubst ) -import Coercion ( mkSymCoercion ) -import TyCon ( TyCon, tyConName, newTyConCo_maybe, tyConTyVars, - isTyConAssoc, tyConFamInst_maybe, - assocTyConArgPoss_maybe ) -import DataCon ( classDataCon, dataConInstArgTys ) -import Class ( Class, classTyCon, classBigSig, classATs ) -import Var ( TyVar, Id, idName, idType, tyVarName ) -import MkId ( mkDictFunId ) -import Name ( Name, getSrcLoc, nameOccName ) -import NameSet ( addListToNameSet, emptyNameSet, minusNameSet, - nameSetToList ) -import Maybe ( fromJust, catMaybes ) -import Monad ( when ) -import List ( find ) -import DynFlags ( DynFlag(Opt_WarnMissingMethods) ) -import SrcLoc ( srcLocSpan, unLoc, noLoc, Located(..), srcSpanStart, - getLoc) -import ListSetOps ( minusList ) -import Util ( snocView, dropList ) +import TcMType +import TcType +import Inst +import InstEnv +import FamInst +import FamInstEnv +import TcDeriv +import TcEnv +import TcHsType +import TcUnify +import TcSimplify +import Type +import Coercion +import TyCon +import DataCon +import Class +import Var +import MkId +import Name +import NameSet +import DynFlags +import SrcLoc +import ListSetOps +import Util import Outputable import Bag -import BasicTypes ( Activation( AlwaysActive ), InlineSpec(..) ) -import HscTypes ( implicitTyThings ) +import BasicTypes +import HscTypes import FastString + +import Data.Maybe +import Control.Monad hiding (zipWithM_, mapAndUnzipM) +import Data.List \end{code} Typechecking instance declarations is done in two passes. The first @@ -146,12 +135,13 @@ Gather up the instance declarations from their various sources tcInstDecls1 -- Deal with both source-code and imported instance decls :: [LTyClDecl Name] -- For deriving stuff -> [LInstDecl Name] -- Source code instance decls + -> [LDerivDecl Name] -- Source code stand-alone deriving decls -> TcM (TcGblEnv, -- The full inst env [InstInfo], -- Source-code instance decls to process; -- contains all dfuns for this module HsValBinds Name) -- Supporting bindings for derived instances -tcInstDecls1 tycl_decls inst_decls +tcInstDecls1 tycl_decls inst_decls deriv_decls = checkNoErrs $ do { -- Stop if addInstInfos etc discovers any errors -- (they recover, so that we get more than one error each @@ -190,7 +180,7 @@ tcInstDecls1 tycl_decls inst_decls -- (4) Compute instances from "deriving" clauses; -- This stuff computes a context for the derived instance -- decl, so it needs to know about all the instances possible - ; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls + ; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls deriv_decls ; addInsts deriv_inst_info $ do { ; gbl_env <- getGblEnv @@ -226,7 +216,11 @@ addInsts infos thing_inside addFamInsts :: [TyThing] -> TcM a -> TcM a addFamInsts tycons thing_inside - = tcExtendLocalFamInstEnv (extractFamInsts tycons) thing_inside + = tcExtendLocalFamInstEnv (map mkLocalFamInstTyThing tycons) thing_inside + where + mkLocalFamInstTyThing (ATyCon tycon) = mkLocalFamInst tycon + mkLocalFamInstTyThing tything = pprPanic "TcInstDcls.addFamInsts" + (ppr tything) \end{code} \begin{code} @@ -469,7 +463,7 @@ tcInstDecl2 :: InstInfo -> TcM (LHsBinds Id) -- Returns a binding for the dfun ------------------------ --- Derived newtype instances +-- Derived newtype instances; surprisingly tricky! -- -- In the case of a newtype, things are rather easy -- class Show a => Foo a b where ... @@ -496,19 +490,20 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) -- inst_head_ty is a PredType ; inst_loc <- getInstLoc origin - ; (rep_dict_id : sc_dict_ids, wrap_fn) + ; (rep_dict_id : sc_dict_ids, wrap_fn, sc_binds) <- make_wrapper inst_loc tvs theta mb_preds -- Here, we are relying on the order of dictionary -- arguments built by NewTypeDerived in TcDeriv; -- namely, that the rep_dict_id comes first ; let (cls, cls_inst_tys) = tcSplitDFunHead inst_head_ty - the_coercion = make_coercion cls cls_inst_tys - coerced_rep_dict = mkHsCoerce the_coercion (HsVar rep_dict_id) + cls_tycon = classTyCon cls + the_coercion = make_coercion cls_tycon cls_inst_tys + coerced_rep_dict = mkHsWrap the_coercion (HsVar rep_dict_id) - ; body <- make_body cls cls_inst_tys inst_head_ty sc_dict_ids coerced_rep_dict + ; body <- make_body cls_tycon cls_inst_tys sc_dict_ids coerced_rep_dict - ; return (unitBag (noLoc $ VarBind dfun_id $ noLoc $ mkHsCoerce wrap_fn body)) } + ; return (sc_binds `snocBag` (noLoc $ VarBind dfun_id $ noLoc $ mkHsWrap wrap_fn body)) } where ----------------------- @@ -523,12 +518,15 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) make_wrapper inst_loc tvs theta (Just preds) -- Case (a) = ASSERT( null tvs && null theta ) do { dicts <- newDictBndrs inst_loc preds - ; extendLIEs dicts - ; return (map instToId dicts, idCoercion) } + ; sc_binds <- addErrCtxt superClassCtxt (tcSimplifySuperClasses [] [] dicts) + -- Use tcSimplifySuperClasses to avoid creating loops, for the + -- same reason as Note [SUPERCLASS-LOOP 1] in TcSimplify + ; return (map instToId dicts, idHsWrapper, sc_binds) } + make_wrapper inst_loc tvs theta Nothing -- Case (b) = do { dicts <- newDictBndrs inst_loc theta ; let dict_ids = map instToId dicts - ; return (dict_ids, mkCoTyLams tvs <.> mkCoLams dict_ids) } + ; return (dict_ids, mkWpTyLams tvs <.> mkWpLams dict_ids, emptyBag) } ----------------------- -- make_coercion @@ -539,16 +537,14 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) -- So we just replace T with CoT, and insert a 'sym' -- NB: we know that k will be >= arity of CoT, because the latter fully eta-reduced - make_coercion cls cls_inst_tys + make_coercion cls_tycon cls_inst_tys | Just (all_tys_but_last, last_ty) <- snocView cls_inst_tys , (tycon, tc_args) <- tcSplitTyConApp last_ty -- Should not fail , Just co_con <- newTyConCo_maybe tycon , let co = mkSymCoercion (mkTyConApp co_con tc_args) - = ExprCoFn (mkTyConApp cls_tycon (all_tys_but_last ++ [co])) + = WpCo (mkTyConApp cls_tycon (all_tys_but_last ++ [co])) | otherwise -- The newtype is transparent; no need for a cast - = idCoercion - where - cls_tycon = classTyCon cls + = idHsWrapper ----------------------- -- make_body @@ -556,7 +552,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) -- (a) no superclasses; then we can just use the coerced dict -- (b) one or more superclasses; then new need to do the unpack/repack - make_body cls cls_inst_tys inst_head_ty sc_dict_ids coerced_rep_dict + make_body cls_tycon cls_inst_tys sc_dict_ids coerced_rep_dict | null sc_dict_ids -- Case (a) = return coerced_rep_dict | otherwise -- Case (b) @@ -566,7 +562,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) pat_dicts = dummy_sc_dict_ids, pat_binds = emptyLHsBinds, pat_args = PrefixCon (map nlVarPat op_ids), - pat_ty = inst_head_ty} + pat_ty = pat_ty} the_match = mkSimpleMatch [noLoc the_pat] the_rhs the_rhs = mkHsConApp cls_data_con cls_inst_tys $ map HsVar (sc_dict_ids ++ op_ids) @@ -575,9 +571,10 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived mb_preds }) -- never otherwise seen in Haskell source code. It'd be -- nicer to generate Core directly! ; return (HsCase (noLoc coerced_rep_dict) $ - MatchGroup [the_match] (mkFunTy inst_head_ty inst_head_ty)) } + MatchGroup [the_match] (mkFunTy pat_ty pat_ty)) } where - cls_data_con = classDataCon cls + pat_ty = mkTyConApp cls_tycon cls_inst_tys + cls_data_con = head (tyConDataCons cls_tycon) cls_arg_tys = dataConInstArgTys cls_data_con cls_inst_tys op_tys = dropList sc_dict_ids cls_arg_tys