%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[Inst]{The @Inst@ type: dictionaries or method instances}
+
+The @Inst@ type: dictionaries or method instances
\begin{code}
module Inst (
tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
- instLoc, getDictClassTys, dictPred,
+ getDictClassTys, dictPred,
- lookupInst, LookupInstResult(..), lookupPred,
+ lookupSimpleInst, LookupInstResult(..), lookupPred,
tcExtendLocalInstEnv, tcGetInstEnvs, getOverlapFlag,
- isDict, isClassDict, isMethod,
- isIPDict, isInheritableInst,
- isTyVarDict, isMethodFor,
+ isDict, isClassDict, isMethod, isImplicInst,
+ isIPDict, isInheritableInst, isMethodOrLit,
+ isTyVarDict, isMethodFor, getDefaultableDicts,
zonkInst, zonkInsts,
instToId, instToVar, instName,
- InstOrigin(..), InstLoc(..), pprInstLoc
+ InstOrigin(..), InstLoc, pprInstLoc
) where
#include "HsVersions.h"
import {-# SOURCE #-} TcExpr( tcPolyExpr )
import {-# SOURCE #-} TcUnify( unifyType )
-import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp,
- HsWrapper(..), (<.>), mkWpTyApps, idHsWrapper,
- nlHsLit, nlHsVar )
-import TcHsSyn ( zonkId )
+import HsSyn
+import TcHsSyn
import TcRnMonad
-import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy )
-import InstEnv ( DFunId, InstEnv, Instance(..), OverlapFlag(..),
- lookupInstEnv, extendInstEnv, pprInstances,
- instanceHead, instanceDFunId, setInstanceDFunId )
-import FunDeps ( checkFunDeps )
-import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType,
- tcInstTyVar, tcInstSkolType
- )
-import TcType ( Type, TcType, TcThetaType, TcTyVarSet, TcPredType,
- BoxyRhoType,
- PredType(..), SkolemInfo(..), typeKind, mkSigmaTy,
- tcSplitForAllTys, applyTys,
- tcSplitPhiTy, tcSplitDFunHead,
- isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
- mkPredTy, mkTyVarTys,
- tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
- isClassPred, isTyVarClassPred,
- getClassPredTys, mkPredName,
- isInheritablePred, isIPPred,
- tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
- pprPred, pprParendType, pprTheta
- )
-import Type ( TvSubst, substTy, substTyVar, substTyWith,
- notElemTvSubst, extendTvSubstList )
-import Unify ( tcMatchTys )
-import Module ( modulePackageId )
-import {- Kind parts of -} Type ( isSubKind )
-import Coercion ( isEqPred )
-import HscTypes ( ExternalPackageState(..), HscEnv(..) )
-import CoreFVs ( idFreeTyVars )
-import DataCon ( dataConWrapId )
-import Id ( Id, idName, idType, mkUserLocal, mkLocalId, isId )
-import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, nameModule,
- isInternalName, setNameUnique )
-import NameSet ( addOneToNameSet )
-import Literal ( inIntRange )
-import Var ( Var, TyVar, tyVarKind, setIdType, isId, mkTyVar )
-import VarEnv ( TidyEnv, emptyTidyEnv )
-import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet )
-import TysWiredIn ( floatDataCon, doubleDataCon )
-import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName )
-import BasicTypes( IPName(..), mapIPName, ipNameName )
-import SrcLoc ( mkSrcSpan, noLoc, unLoc, Located(..) )
-import DynFlags ( DynFlag(..), DynFlags(..), dopt )
-import Maybes ( isJust )
+import TcEnv
+import InstEnv
+import FunDeps
+import TcMType
+import TcType
+import Type
+import Class
+import Unify
+import Module
+import Coercion
+import HscTypes
+import CoreFVs
+import DataCon
+import Id
+import Name
+import NameSet
+import Literal
+import Var ( Var, TyVar )
+import qualified Var
+import VarEnv
+import VarSet
+import TysWiredIn
+import PrelNames
+import BasicTypes
+import SrcLoc
+import DynFlags
+import Maybes
+import Util
import Outputable
\end{code}
id = instToVar inst
instToVar :: Inst -> Var
-instToVar (LitInst nm _ ty _) = mkLocalId nm ty
-instToVar (Method id _ _ _ _) = id
-instToVar (Dict nm pred _)
- | isEqPred pred = mkTyVar nm (mkPredTy pred)
+instToVar (LitInst {tci_name = nm, tci_ty = ty})
+ = mkLocalId nm ty
+instToVar (Method {tci_id = id})
+ = id
+instToVar (Dict {tci_name = nm, tci_pred = pred})
+ | isEqPred pred = Var.mkCoVar nm (mkPredTy pred)
| otherwise = mkLocalId nm (mkPredTy pred)
-
-instLoc (Dict _ _ loc) = loc
-instLoc (Method _ _ _ _ loc) = loc
-instLoc (LitInst _ _ _ loc) = loc
-
-dictPred (Dict _ pred _ ) = pred
-dictPred inst = pprPanic "dictPred" (ppr inst)
-
-getDictClassTys (Dict _ pred _) = getClassPredTys pred
+instToVar (ImplicInst {tci_name = nm, tci_tyvars = tvs, tci_given = givens,
+ tci_wanted = wanteds})
+ = mkLocalId nm (mkImplicTy tvs givens wanteds)
+
+instType :: Inst -> Type
+instType (LitInst {tci_ty = ty}) = ty
+instType (Method {tci_id = id}) = idType id
+instType (Dict {tci_pred = pred}) = mkPredTy pred
+instType imp@(ImplicInst {}) = mkImplicTy (tci_tyvars imp) (tci_given imp)
+ (tci_wanted imp)
+
+mkImplicTy tvs givens wanteds -- The type of an implication constraint
+ = -- pprTrace "mkImplicTy" (ppr givens) $
+ mkForAllTys tvs $
+ mkPhiTy (map dictPred givens) $
+ if isSingleton wanteds then
+ instType (head wanteds)
+ else
+ mkTupleTy Boxed (length wanteds) (map instType wanteds)
+
+dictPred (Dict {tci_pred = pred}) = pred
+dictPred inst = pprPanic "dictPred" (ppr inst)
+
+getDictClassTys (Dict {tci_pred = pred}) = getClassPredTys pred
+getDictClassTys inst = pprPanic "getDictClassTys" (ppr inst)
-- fdPredsOfInst is used to get predicates that contain functional
-- dependencies *or* might do so. The "might do" part is because
-- Leaving these in is really important for the call to fdPredsOfInsts
-- in TcSimplify.inferLoop, because the result is fed to 'grow',
-- which is supposed to be conservative
-fdPredsOfInst (Dict _ pred _) = [pred]
-fdPredsOfInst (Method _ _ _ theta _) = theta
-fdPredsOfInst other = [] -- LitInsts etc
+fdPredsOfInst (Dict {tci_pred = pred}) = [pred]
+fdPredsOfInst (Method {tci_theta = theta}) = theta
+fdPredsOfInst (ImplicInst {tci_given = gs,
+ tci_wanted = ws}) = fdPredsOfInsts (gs ++ ws)
+fdPredsOfInst (LitInst {}) = []
fdPredsOfInsts :: [Inst] -> [PredType]
fdPredsOfInsts insts = concatMap fdPredsOfInst insts
-isInheritableInst (Dict _ pred _) = isInheritablePred pred
-isInheritableInst (Method _ _ _ theta _) = all isInheritablePred theta
-isInheritableInst other = True
+isInheritableInst (Dict {tci_pred = pred}) = isInheritablePred pred
+isInheritableInst (Method {tci_theta = theta}) = all isInheritablePred theta
+isInheritableInst other = True
+
+---------------------------------
+-- Get the implicit parameters mentioned by these Insts
+-- NB: the results of these functions are insensitive to zonking
ipNamesOfInsts :: [Inst] -> [Name]
ipNamesOfInst :: Inst -> [Name]
--- Get the implicit parameters mentioned by these Insts
--- NB: ?x and %x get different Names
ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst]
-ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n]
-ipNamesOfInst (Method _ _ _ theta _) = [ipNameName n | IParam n _ <- theta]
-ipNamesOfInst other = []
+ipNamesOfInst (Dict {tci_pred = IParam n _}) = [ipNameName n]
+ipNamesOfInst (Method {tci_theta = theta}) = [ipNameName n | IParam n _ <- theta]
+ipNamesOfInst other = []
+---------------------------------
tyVarsOfInst :: Inst -> TcTyVarSet
-tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty
-tyVarsOfInst (Dict _ pred _) = tyVarsOfPred pred
-tyVarsOfInst (Method _ id tys _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
- -- The id might have free type variables; in the case of
- -- locally-overloaded class methods, for example
+tyVarsOfInst (LitInst {tci_ty = ty}) = tyVarsOfType ty
+tyVarsOfInst (Dict {tci_pred = pred}) = tyVarsOfPred pred
+tyVarsOfInst (Method {tci_oid = id, tci_tys = tys}) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
+ -- The id might have free type variables; in the case of
+ -- locally-overloaded class methods, for example
+tyVarsOfInst (ImplicInst {tci_tyvars = tvs, tci_given = givens, tci_wanted = wanteds})
+ = (tyVarsOfInsts givens `unionVarSet` tyVarsOfInsts wanteds) `minusVarSet` mkVarSet tvs
tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
~~~~~~~~~~
\begin{code}
isDict :: Inst -> Bool
-isDict (Dict _ _ _) = True
-isDict other = False
+isDict (Dict {}) = True
+isDict other = False
isClassDict :: Inst -> Bool
-isClassDict (Dict _ pred _) = isClassPred pred
-isClassDict other = False
+isClassDict (Dict {tci_pred = pred}) = isClassPred pred
+isClassDict other = False
isTyVarDict :: Inst -> Bool
-isTyVarDict (Dict _ pred _) = isTyVarClassPred pred
-isTyVarDict other = False
+isTyVarDict (Dict {tci_pred = pred}) = isTyVarClassPred pred
+isTyVarDict other = False
isIPDict :: Inst -> Bool
-isIPDict (Dict _ pred _) = isIPPred pred
-isIPDict other = False
+isIPDict (Dict {tci_pred = pred}) = isIPPred pred
+isIPDict other = False
+
+isImplicInst (ImplicInst {}) = True
+isImplicInst other = False
isMethod :: Inst -> Bool
isMethod (Method {}) = True
isMethod other = False
isMethodFor :: TcIdSet -> Inst -> Bool
-isMethodFor ids (Method uniq id tys _ loc) = id `elemVarSet` ids
-isMethodFor ids inst = False
-\end{code}
+isMethodFor ids (Method {tci_oid = id}) = id `elemVarSet` ids
+isMethodFor ids inst = False
+isMethodOrLit :: Inst -> Bool
+isMethodOrLit (Method {}) = True
+isMethodOrLit (LitInst {}) = True
+isMethodOrLit other = False
+\end{code}
+\begin{code}
+getDefaultableDicts :: [Inst] -> ([(Inst, Class, TcTyVar)], TcTyVarSet)
+-- Look for free dicts of the form (C tv), even inside implications
+-- *and* the set of tyvars mentioned by all *other* constaints
+-- This disgustingly ad-hoc function is solely to support defaulting
+getDefaultableDicts insts
+ = (concat ps, unionVarSets tvs)
+ where
+ (ps, tvs) = mapAndUnzip get insts
+ get d@(Dict {tci_pred = ClassP cls [ty]})
+ | Just tv <- tcGetTyVar_maybe ty = ([(d,cls,tv)], emptyVarSet)
+ | otherwise = ([], tyVarsOfType ty)
+ get (ImplicInst {tci_tyvars = tvs, tci_wanted = wanteds})
+ = ([ up | up@(_,_,tv) <- ups, not (tv `elemVarSet` tv_set)],
+ ftvs `minusVarSet` tv_set)
+ where
+ tv_set = mkVarSet tvs
+ (ups, ftvs) = getDefaultableDicts wanteds
+ get inst = ([], tyVarsOfInst inst)
+\end{code}
%************************************************************************
%* *
newDictBndr :: InstLoc -> TcPredType -> TcM Inst
newDictBndr inst_loc pred
= do { uniq <- newUnique
- ; let name = mkPredName uniq (instLocSrcLoc inst_loc) pred
- ; return (Dict name pred inst_loc) }
+ ; let name = mkPredName uniq inst_loc pred
+ ; return (Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc}) }
----------------
instCall :: InstOrigin -> [TcType] -> TcThetaType -> TcM HsWrapper
instCallDicts loc (pred : preds)
= do { uniq <- newUnique
- ; let name = mkPredName uniq (instLocSrcLoc loc) pred
- dict = Dict name pred loc
+ ; let name = mkPredName uniq loc pred
+ dict = Dict {tci_name = name, tci_pred = pred, tci_loc = loc}
; (dicts, co_fn) <- instCallDicts loc preds
; return (dict:dicts, co_fn <.> WpApp (instToId dict)) }
-------------
cloneDict :: Inst -> TcM Inst -- Only used for linear implicit params
-cloneDict (Dict nm ty loc) = newUnique `thenM` \ uniq ->
- returnM (Dict (setNameUnique nm uniq) ty loc)
+cloneDict dict@(Dict nm ty loc) = do { uniq <- newUnique
+ ; return (dict {tci_name = setNameUnique nm uniq}) }
+cloneDict other = pprPanic "cloneDict" (ppr other)
-- For vanilla implicit parameters, there is only one in scope
-- at any time, so we used to use the name of the implicit parameter itself
newUnique `thenM` \ uniq ->
let
pred = IParam ip_name ty
- name = mkPredName uniq (instLocSrcLoc inst_loc) pred
- dict = Dict name pred inst_loc
+ name = mkPredName uniq inst_loc pred
+ dict = Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc}
in
returnM (mapIPName (\n -> instToId dict) ip_name, dict)
\end{code}
+\begin{code}
+mkPredName :: Unique -> InstLoc -> PredType -> Name
+mkPredName uniq loc pred_ty
+ = mkInternalName uniq occ (srcSpanStart (instLocSpan loc))
+ where
+ occ = case pred_ty of
+ ClassP cls tys -> mkDictOcc (getOccName cls)
+ IParam ip ty -> getOccName (ipNameName ip)
+\end{code}
%************************************************************************
%* *
checkKind tv ty
= do { let ty1 = ty
-- ty1 <- zonkTcType ty
- ; if typeKind ty1 `isSubKind` tyVarKind tv
+ ; if typeKind ty1 `isSubKind` Var.tyVarKind tv
then return ()
else
pprPanic "checkKind: adding kind constraint"
- (vcat [ppr tv <+> ppr (tyVarKind tv),
+ (vcat [ppr tv <+> ppr (Var.tyVarKind tv),
ppr ty <+> ppr ty1 <+> ppr (typeKind ty1)])
}
-- do { tv1 <- tcInstTyVar tv
let
(theta,tau) = tcSplitPhiTy (applyTys (idType id) tys)
meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc
- inst = Method meth_id id tys theta inst_loc
- loc = instLocSrcLoc inst_loc
+ inst = Method {tci_id = meth_id, tci_oid = id, tci_tys = tys,
+ tci_theta = theta, tci_loc = inst_loc}
+ loc = srcSpanStart (instLocSpan inst_loc)
in
returnM inst
\end{code}
\begin{code}
zonkInst :: Inst -> TcM Inst
-zonkInst (Dict name pred loc)
+zonkInst dict@(Dict { tci_pred = pred})
= zonkTcPredType pred `thenM` \ new_pred ->
- returnM (Dict name new_pred loc)
+ returnM (dict {tci_pred = new_pred})
-zonkInst (Method m id tys theta loc)
+zonkInst meth@(Method {tci_oid = id, tci_tys = tys, tci_theta = theta})
= zonkId id `thenM` \ new_id ->
-- Essential to zonk the id in case it's a local variable
-- Can't use zonkIdOcc because the id might itself be
zonkTcTypes tys `thenM` \ new_tys ->
zonkTcThetaType theta `thenM` \ new_theta ->
- returnM (Method m new_id new_tys new_theta loc)
+ returnM (meth { tci_oid = new_id, tci_tys = new_tys, tci_theta = new_theta })
+ -- No need to zonk the tci_id
-zonkInst (LitInst nm lit ty loc)
+zonkInst lit@(LitInst {tci_ty = ty})
= zonkTcType ty `thenM` \ new_ty ->
- returnM (LitInst nm lit new_ty loc)
+ returnM (lit {tci_ty = new_ty})
+
+zonkInst implic@(ImplicInst {})
+ = ASSERT( all isImmutableTyVar (tci_tyvars implic) )
+ do { givens' <- zonkInsts (tci_given implic)
+ ; wanteds' <- zonkInsts (tci_wanted implic)
+ ; return (implic {tci_given = givens',tci_wanted = wanteds'}) }
zonkInsts insts = mappM zonkInst insts
\end{code}
pprDictsTheta :: [Inst] -> SDoc
-- Print in type-like fashion (Eq a, Show b)
-pprDictsTheta dicts = pprTheta (map dictPred dicts)
+-- The Inst can be an implication constraint, but not a Method or LitInst
+pprDictsTheta insts = parens (sep (punctuate comma (map (ppr . instType) insts)))
pprDictsInFull :: [Inst] -> SDoc
-- Print in type-like fashion, but with source location
pprDictsInFull dicts
= vcat (map go dicts)
where
- go dict = sep [quotes (ppr (dictPred dict)), nest 2 (pprInstLoc (instLoc dict))]
+ go dict = sep [quotes (ppr (instType dict)), nest 2 (pprInstArising dict)]
pprInsts :: [Inst] -> SDoc
-- Debugging: print the evidence :: type
-pprInsts insts = brackets (interpp'SP insts)
+pprInsts insts = brackets (interpp'SP insts)
pprInst, pprInstInFull :: Inst -> SDoc
-- Debugging: print the evidence :: type
-pprInst (LitInst nm lit ty loc) = ppr nm <+> dcolon <+> ppr ty
-pprInst (Dict nm pred loc) = ppr nm <+> dcolon <+> pprPred pred
-
-pprInst m@(Method inst_id id tys theta loc)
- = ppr inst_id <+> dcolon <+>
- braces (sep [ppr id <+> ptext SLIT("at"),
- brackets (sep (map pprParendType tys))])
+pprInst inst = ppr (instName inst) <+> dcolon
+ <+> (braces (ppr (instType inst)) $$
+ ifPprDebug implic_stuff)
+ where
+ implic_stuff | isImplicInst inst = ppr (tci_reft inst)
+ | otherwise = empty
-pprInstInFull inst
- = sep [quotes (pprInst inst), nest 2 (pprInstLoc (instLoc inst))]
+pprInstInFull inst = sep [quotes (pprInst inst), nest 2 (pprInstArising inst)]
tidyInst :: TidyEnv -> Inst -> Inst
-tidyInst env (LitInst nm lit ty loc) = LitInst nm lit (tidyType env ty) loc
-tidyInst env (Dict nm pred loc) = Dict nm (tidyPred env pred) loc
-tidyInst env (Method u id tys theta loc) = Method u id (tidyTypes env tys) theta loc
+tidyInst env lit@(LitInst {tci_ty = ty}) = lit {tci_ty = tidyType env ty}
+tidyInst env dict@(Dict {tci_pred = pred}) = dict {tci_pred = tidyPred env pred}
+tidyInst env meth@(Method {tci_tys = tys}) = meth {tci_tys = tidyTypes env tys}
+tidyInst env implic@(ImplicInst {})
+ = implic { tci_tyvars = tvs'
+ , tci_given = map (tidyInst env') (tci_given implic)
+ , tci_wanted = map (tidyInst env') (tci_wanted implic) }
+ where
+ (env', tvs') = mapAccumL tidyTyVarBndr env (tci_tyvars implic)
tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst])
-- This function doesn't assume that the tyvars are in scope
-- We use tcInstSkolType because we don't want to allocate fresh
-- *meta* type variables.
let dfun = instanceDFunId ispec
- ; (tvs', theta', tau') <- tcInstSkolType (InstSkol dfun) (idType dfun)
+ ; (tvs', theta', tau') <- tcInstSkolType InstSkol (idType dfun)
; let (cls, tys') = tcSplitDFunHead tau'
dfun' = setIdType dfun (mkSigmaTy tvs' theta' tau')
ispec' = setInstanceDFunId ispec dfun'
\begin{code}
data LookupInstResult
= NoInstance
- | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal
- | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts
+ | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts
+
+lookupSimpleInst :: Inst -> TcM LookupInstResult
+-- This is "simple" in tthat it returns NoInstance for implication constraints
-lookupInst :: Inst -> TcM LookupInstResult
-- It's important that lookupInst does not put any new stuff into
-- the LIE. Instead, any Insts needed by the lookup are returned in
-- the LookupInstResult, where they can be further processed by tcSimplify
+--------------------- Implications ------------------------
+lookupSimpleInst (ImplicInst {}) = return NoInstance
--- Methods
-
-lookupInst inst@(Method _ id tys theta loc)
+--------------------- Methods ------------------------
+lookupSimpleInst (Method {tci_oid = id, tci_tys = tys, tci_theta = theta, tci_loc = loc})
= do { (dicts, dict_app) <- instCallDicts loc theta
; let co_fn = dict_app <.> mkWpTyApps tys
; return (GenInst dicts (L span $ HsWrap co_fn (HsVar id))) }
where
- span = instLocSrcSpan loc
-
--- Literals
+ span = instLocSpan loc
+--------------------- Literals ------------------------
-- Look for short cuts first: if the literal is *definitely* a
-- int, integer, float or a double, generate the real thing here.
-- This is essential (see nofib/spectral/nucleic).
-- [Same shortcut as in newOverloadedLit, but we
-- may have done some unification by now]
-lookupInst inst@(LitInst _nm (HsIntegral i from_integer_name) ty loc)
+lookupSimpleInst (LitInst {tci_lit = HsIntegral i from_integer_name, tci_ty = ty, tci_loc = loc})
| Just expr <- shortCutIntLit i ty
- = returnM (GenInst [] (noLoc expr)) -- GenInst, not SimpleInst, because
- -- expr may be a constructor application
+ = returnM (GenInst [] (noLoc expr))
| otherwise
= ASSERT( from_integer_name `isHsVar` fromIntegerName ) -- A LitInst invariant
tcLookupId fromIntegerName `thenM` \ from_integer ->
tcInstClassOp loc from_integer [ty] `thenM` \ method_inst ->
mkIntegerLit i `thenM` \ integer_lit ->
returnM (GenInst [method_inst]
- (mkHsApp (L (instLocSrcSpan loc)
+ (mkHsApp (L (instLocSpan loc)
(HsVar (instToId method_inst))) integer_lit))
-lookupInst inst@(LitInst _nm (HsFractional f from_rat_name) ty loc)
+lookupSimpleInst (LitInst {tci_lit = HsFractional f from_rat_name, tci_ty = ty, tci_loc = loc})
| Just expr <- shortCutFracLit f ty
= returnM (GenInst [] (noLoc expr))
tcLookupId fromRationalName `thenM` \ from_rational ->
tcInstClassOp loc from_rational [ty] `thenM` \ method_inst ->
mkRatLit f `thenM` \ rat_lit ->
- returnM (GenInst [method_inst] (mkHsApp (L (instLocSrcSpan loc)
+ returnM (GenInst [method_inst] (mkHsApp (L (instLocSpan loc)
(HsVar (instToId method_inst))) rat_lit))
--- Dictionaries
-lookupInst (Dict _ pred loc)
+--------------------- Dictionaries ------------------------
+lookupSimpleInst (Dict {tci_pred = pred, tci_loc = loc})
= do { mb_result <- lookupPred pred
; case mb_result of {
Nothing -> return NoInstance ;
-- any nested for-alls in rho. So the in-scope set is unchanged
dfun_rho = substTy tenv' rho
(theta, _) = tcSplitPhiTy dfun_rho
- src_loc = instLocSrcSpan loc
+ src_loc = instLocSpan loc
dfun = HsVar dfun_id
tys = map (substTyVar tenv') tyvars
; if null theta then
- returnM (SimpleInst (L src_loc $ HsWrap (mkWpTyApps tys) dfun))
+ returnM (GenInst [] (L src_loc $ HsWrap (mkWpTyApps tys) dfun))
else do
{ (dicts, dict_app) <- instCallDicts loc theta
; let co_fn = dict_app <.> mkWpTyApps tys
; return Nothing }
}}
-lookupPred ip_pred = return Nothing
+lookupPred ip_pred = return Nothing -- Implicit parameters
record_dfun_usage dfun_id
= do { hsc_env <- getTopEnv
msg = vcat [ptext SLIT("When checking that") <+> quotes (ppr name) <+>
ptext SLIT("(needed by a syntactic construct)"),
nest 2 (ptext SLIT("has the required type:") <+> ppr (tidyType tidy_env ty)),
- nest 2 (pprInstLoc inst_loc)]
+ nest 2 (ptext SLIT("arising from") <+> pprInstLoc inst_loc)]
in
returnM (tidy_env, msg)
\end{code}
projects / ghc-hetmet.git / blobdiff