\begin{code}
module Inst (
- LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE,
+ LIE, emptyLIE, unitLIE, plusLIE, consLIE,
plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
+ showLIE,
- Inst, OverloadedLit(..),
- pprInst, pprInsts, pprInstsInFull, tidyInst, tidyInsts,
+ Inst,
+ pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts,
- InstanceMapper,
+ newDictsFromOld, newDicts, cloneDict,
+ newOverloadedLit, newIPDict,
+ newMethod, newMethodFromName, newMethodWithGivenTy,
+ tcInstClassOp, tcInstCall, tcInstDataCon,
+ tcSyntaxName, tcStdSyntaxName,
- newDictFromOld, newDicts, newClassDicts, newDictsAtLoc,
- newMethod, newMethodWithGivenTy, newOverloadedLit,
- newIPDict, instOverloadedFun,
+ tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
+ ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
+ instLoc, getDictClassTys, dictPred,
- tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, instLoc, getDictClassTys,
- getFunDeps, getFunDepsOfLIE,
- getIPs, getIPsOfLIE,
- getAllFunDeps, getAllFunDepsOfLIE,
- partitionLIEbyMeth,
+ lookupInst, LookupInstResult(..),
- lookupInst, lookupSimpleInst, LookupInstResult(..),
-
- isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor, notFunDep,
+ isDict, isClassDict, isMethod,
+ isLinearInst, linearInstType, isIPDict, isInheritableInst,
+ isTyVarDict, isStdClassTyVarDict, isMethodFor,
instBindingRequired, instCanBeGeneralised,
- zonkInst, zonkFunDeps, zonkTvFunDeps, instToId, instToIdBndr,
+ zonkInst, zonkInsts,
+ instToId, instName,
- InstOrigin(..), InstLoc, pprInstLoc
+ InstOrigin(..), InstLoc(..), pprInstLoc
) where
#include "HsVersions.h"
-import HsSyn ( HsLit(..), HsExpr(..) )
-import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr, RenamedPat )
-import TcHsSyn ( TcExpr, TcId,
- mkHsTyApp, mkHsDictApp, zonkId
+import {-# SOURCE #-} TcExpr( tcCheckSigma )
+
+import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) )
+import TcHsSyn ( TcExpr, TcId, TcIdSet,
+ mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId,
+ mkCoercion, ExprCoFn
)
-import TcMonad
-import TcEnv ( TcIdSet, tcLookupValueByKey, tcLookupTyConByKey )
-import TcType ( TcThetaType,
- TcType, TcTauType, TcTyVarSet,
- zonkTcTyVars, zonkTcType, zonkTcTypes,
- zonkTcThetaType
+import TcRnMonad
+import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl )
+import InstEnv ( InstLookupResult(..), lookupInstEnv )
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
+ zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
-import Bag
-import Class ( classInstEnv, Class )
-import FunDeps ( instantiateFdClassTys )
-import Id ( Id, idFreeTyVars, idType, mkUserLocal, mkSysLocal )
-import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
-import Name ( OccName, Name, mkDictOcc, mkMethodOcc, getOccName, nameUnique )
-import PprType ( pprPred )
-import InstEnv ( InstEnv, lookupInstEnv )
-import SrcLoc ( SrcLoc )
-import Type ( Type, PredType(..), ThetaType,
- mkTyVarTy, isTyVarTy, mkDictTy, mkPredTy,
- splitForAllTys, splitSigmaTy,
- splitRhoTy, tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
- mkSynTy, tidyOpenType, tidyOpenTypes
+import TcType ( Type, TcType, TcThetaType, TcTyVarSet,
+ SourceType(..), PredType, TyVarDetails(VanillaTv),
+ tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
+ tcSplitPhiTy, mkGenTyConApp,
+ isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
+ tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
+ tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
+ isClassPred, isTyVarClassPred, isLinearPred,
+ getClassPredTys, getClassPredTys_maybe, mkPredName,
+ isInheritablePred, isIPPred,
+ tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy
)
-import InstEnv ( InstEnv )
-import Subst ( emptyInScopeSet, mkSubst,
- substTy, substClasses, mkTyVarSubst, mkTopTyVarSubst
- )
-import TyCon ( TyCon )
+import CoreFVs ( idFreeTyVars )
+import DataCon ( DataCon,dataConSig )
+import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique )
+import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
+import Name ( Name, mkMethodOcc, getOccName )
+import PprType ( pprPred, pprParendType )
+import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst )
+import Literal ( inIntRange )
import Var ( TyVar )
-import VarEnv ( lookupVarEnv, TidyEnv,
- lookupSubstEnv, SubstResult(..)
- )
+import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) )
import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
-import TysPrim ( intPrimTy, floatPrimTy, doublePrimTy )
-import TysWiredIn ( intDataCon, isIntTy, inIntRange,
- floatDataCon, isFloatTy,
- doubleDataCon, isDoubleTy,
- integerTy, isIntegerTy
- )
-import Unique ( fromRationalClassOpKey, rationalTyConKey,
- fromIntClassOpKey, fromIntegerClassOpKey, Unique
- )
-import Maybes ( expectJust )
-import List ( partition )
-import Maybe ( catMaybes )
-import Util ( thenCmp, zipWithEqual, mapAccumL )
+import TysWiredIn ( floatDataCon, doubleDataCon )
+import PrelNames( fromIntegerName, fromRationalName, rationalTyConName )
+import BasicTypes( IPName(..), mapIPName, ipNameName )
+import UniqSupply( uniqsFromSupply )
import Outputable
\end{code}
-%************************************************************************
-%* *
-\subsection[Inst-collections]{LIE: a collection of Insts}
-%* *
-%************************************************************************
-
-\begin{code}
-type LIE = Bag Inst
-
-isEmptyLIE = isEmptyBag
-emptyLIE = emptyBag
-unitLIE inst = unitBag inst
-mkLIE insts = listToBag insts
-plusLIE lie1 lie2 = lie1 `unionBags` lie2
-consLIE inst lie = inst `consBag` lie
-plusLIEs lies = unionManyBags lies
-lieToList = bagToList
-listToLIE = listToBag
-
-zonkLIE :: LIE -> NF_TcM s LIE
-zonkLIE lie = mapBagNF_Tc zonkInst lie
-
-pprInsts :: [Inst] -> SDoc
-pprInsts insts = parens (sep (punctuate comma (map pprInst insts)))
-
-
-pprInstsInFull insts
- = vcat (map go insts)
- where
- go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst)
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[Inst-types]{@Inst@ types}
-%* *
-%************************************************************************
-
-An @Inst@ is either a dictionary, an instance of an overloaded
-literal, or an instance of an overloaded value. We call the latter a
-``method'' even though it may not correspond to a class operation.
-For example, we might have an instance of the @double@ function at
-type Int, represented by
-
- Method 34 doubleId [Int] origin
-
-\begin{code}
-data Inst
- = Dict
- Unique
- TcPredType
- InstLoc
-
- | Method
- Unique
-
- TcId -- The overloaded function
- -- This function will be a global, local, or ClassOpId;
- -- inside instance decls (only) it can also be an InstId!
- -- The id needn't be completely polymorphic.
- -- You'll probably find its name (for documentation purposes)
- -- inside the InstOrigin
-
- [TcType] -- The types to which its polymorphic tyvars
- -- should be instantiated.
- -- These types must saturate the Id's foralls.
-
- TcThetaType -- The (types of the) dictionaries to which the function
- -- must be applied to get the method
-
- TcTauType -- The type of the method
-
- InstLoc
-
- -- INVARIANT: in (Method u f tys theta tau loc)
- -- type of (f tys dicts(from theta)) = tau
-
- | LitInst
- Unique
- OverloadedLit
- TcType -- The type at which the literal is used
- InstLoc
-
- | FunDep
- Class -- the class from which this arises
- [([TcType], [TcType])]
- InstLoc
-
-data OverloadedLit
- = OverloadedIntegral Integer -- The number
- | OverloadedFractional Rational -- The number
-\end{code}
-
-Ordering
-~~~~~~~~
-@Insts@ are ordered by their class/type info, rather than by their
-unique. This allows the context-reduction mechanism to use standard finite
-maps to do their stuff.
-
-\begin{code}
-instance Ord Inst where
- compare = cmpInst
-instance Ord PredType where
- compare = cmpPred
-
-instance Eq Inst where
- (==) i1 i2 = case i1 `cmpInst` i2 of
- EQ -> True
- other -> False
-instance Eq PredType where
- (==) p1 p2 = case p1 `cmpPred` p2 of
- EQ -> True
- other -> False
-
-cmpInst (Dict _ pred1 _) (Dict _ pred2 _)
- = (pred1 `cmpPred` pred2)
-cmpInst (Dict _ _ _) other
- = LT
-
-cmpInst (Method _ _ _ _ _ _) (Dict _ _ _)
- = GT
-cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _)
- = (id1 `compare` id2) `thenCmp` (tys1 `compare` tys2)
-cmpInst (Method _ _ _ _ _ _) other
- = LT
-
-cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _)
- = (lit1 `cmpOverLit` lit2) `thenCmp` (ty1 `compare` ty2)
-cmpInst (LitInst _ _ _ _) (FunDep _ _ _)
- = LT
-cmpInst (LitInst _ _ _ _) other
- = GT
-
-cmpInst (FunDep clas1 fds1 _) (FunDep clas2 fds2 _)
- = (clas1 `compare` clas2) `thenCmp` (fds1 `compare` fds2)
-cmpInst (FunDep _ _ _) other
- = GT
-
-cmpPred (Class c1 tys1) (Class c2 tys2)
- = (c1 `compare` c2) `thenCmp` (tys1 `compare` tys2)
-cmpPred (IParam n1 ty1) (IParam n2 ty2)
- = (n1 `compare` n2) `thenCmp` (ty1 `compare` ty2)
-cmpPred (Class _ _) (IParam _ _) = LT
-cmpPred _ _ = GT
-
-cmpOverLit (OverloadedIntegral i1) (OverloadedIntegral i2) = i1 `compare` i2
-cmpOverLit (OverloadedFractional f1) (OverloadedFractional f2) = f1 `compare` f2
-cmpOverLit (OverloadedIntegral _) (OverloadedFractional _) = LT
-cmpOverLit (OverloadedFractional _) (OverloadedIntegral _) = GT
-\end{code}
-
Selection
~~~~~~~~~
\begin{code}
-instLoc (Dict u pred loc) = loc
-instLoc (Method u _ _ _ _ loc) = loc
-instLoc (LitInst u lit ty loc) = loc
-instLoc (FunDep _ _ loc) = loc
+instName :: Inst -> Name
+instName inst = idName (instToId inst)
-getDictClassTys (Dict u (Class clas tys) _) = (clas, tys)
+instToId :: Inst -> TcId
+instToId (Dict id _ _) = id
+instToId (Method id _ _ _ _ _) = id
+instToId (LitInst id _ _ _) = id
-getFunDeps (FunDep clas fds _) = Just (clas, fds)
-getFunDeps _ = Nothing
+instLoc (Dict _ _ loc) = loc
+instLoc (Method _ _ _ _ _ loc) = loc
+instLoc (LitInst _ _ _ loc) = loc
-getFunDepsOfLIE lie = catMaybes (map getFunDeps (lieToList lie))
+dictPred (Dict _ pred _ ) = pred
+dictPred inst = pprPanic "dictPred" (ppr inst)
-getIPsOfPred (IParam n ty) = [(n, ty)]
-getIPsOfPred _ = []
-getIPsOfTheta theta = concatMap getIPsOfPred theta
+getDictClassTys (Dict _ pred _) = getClassPredTys pred
-getIPs (Dict u (IParam n ty) loc) = [(n, ty)]
-getIPs (Method u id _ theta t loc) = getIPsOfTheta theta
-getIPs _ = []
+-- fdPredsOfInst is used to get predicates that contain functional
+-- dependencies *or* might do so. The "might do" part is because
+-- a constraint (C a b) might have a superclass with FDs
+-- 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
-getIPsOfLIE lie = concatMap getIPs (lieToList lie)
+fdPredsOfInsts :: [Inst] -> [PredType]
+fdPredsOfInsts insts = concatMap fdPredsOfInst insts
-getAllFunDeps (FunDep clas fds _) = fds
-getAllFunDeps inst = map (\(n,ty) -> ([], [ty])) (getIPs inst)
+isInheritableInst (Dict _ pred _) = isInheritablePred pred
+isInheritableInst (Method _ _ _ theta _ _) = all isInheritablePred theta
+isInheritableInst other = True
-getAllFunDepsOfLIE lie = concat (map getAllFunDeps (lieToList lie))
-partitionLIEbyMeth pred lie
- = foldlTc (partMethod pred) (emptyLIE, emptyLIE) insts
- where insts = lieToList lie
+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]
-partMethod pred (ips, lie) m@(Method u id tys theta tau loc)
- = if null ips_ then
- returnTc (ips, consLIE m lie)
- else if null theta_ then
- returnTc (consLIE m ips, lie)
- else
- newMethodWith id tys theta_ tau loc `thenTc` \ new_m2 ->
- let id_m1 = instToIdBndr new_m2
- new_m1 = Method u id_m1 {- tys -} [] ips_ tau loc in
- -- newMethodWith id_m1 tys ips_ tau loc `thenTc` \ new_m1 ->
- returnTc (consLIE new_m1 ips, consLIE new_m2 lie)
- where (ips_, theta_) = partition pred theta
+ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n]
+ipNamesOfInst (Method _ _ _ 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 _ _ ty _) = tyVarsOfType ty
-tyVarsOfInst (FunDep _ fds _)
- = foldr unionVarSet emptyVarSet (map tyVarsOfFd fds)
- where tyVarsOfFd (ts1, ts2) =
- tyVarsOfTypes ts1 `unionVarSet` tyVarsOfTypes ts2
-tyVarsOfInsts insts
- = foldr unionVarSet emptyVarSet (map tyVarsOfInst insts)
-tyVarsOfLIE lie
- = foldr unionVarSet emptyVarSet (map tyVarsOfInst insts)
- where insts = lieToList lie
+tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
+tyVarsOfLIE lie = tyVarsOfInsts (lieToList lie)
\end{code}
Predicates
~~~~~~~~~~
\begin{code}
isDict :: Inst -> Bool
-isDict (Dict _ (Class _ _) _) = True
-isDict other = False
+isDict (Dict _ _ _) = True
+isDict other = False
-isMethodFor :: TcIdSet -> Inst -> Bool
-isMethodFor ids (Method uniq id tys _ _ loc)
- = id `elemVarSet` ids
-isMethodFor ids inst
- = False
+isClassDict :: Inst -> Bool
+isClassDict (Dict _ pred _) = isClassPred pred
+isClassDict other = False
isTyVarDict :: Inst -> Bool
-isTyVarDict (Dict _ (Class _ tys) _) = all isTyVarTy tys
-isTyVarDict other = False
+isTyVarDict (Dict _ pred _) = isTyVarClassPred pred
+isTyVarDict other = False
+
+isIPDict :: Inst -> Bool
+isIPDict (Dict _ pred _) = isIPPred pred
+isIPDict 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
+
+isLinearInst :: Inst -> Bool
+isLinearInst (Dict _ pred _) = isLinearPred pred
+isLinearInst other = False
+ -- We never build Method Insts that have
+ -- linear implicit paramters in them.
+ -- Hence no need to look for Methods
+ -- See TcExpr.tcId
+
+linearInstType :: Inst -> TcType -- %x::t --> t
+linearInstType (Dict _ (IParam _ ty) _) = ty
-isStdClassTyVarDict (Dict _ (Class clas [ty]) _)
- = isStandardClass clas && isTyVarTy ty
-isStdClassTyVarDict other
- = False
-notFunDep :: Inst -> Bool
-notFunDep (FunDep _ _ _) = False
-notFunDep other = True
+isStdClassTyVarDict (Dict _ pred _) = case getClassPredTys_maybe pred of
+ Just (clas, [ty]) -> isStandardClass clas && tcIsTyVarTy ty
+ other -> False
\end{code}
Two predicates which deal with the case where class constraints don't
\begin{code}
instBindingRequired :: Inst -> Bool
-instBindingRequired (Dict _ (Class clas _) _) = not (isNoDictClass clas)
-instBindingRequired (Dict _ (IParam _ _) _) = False
-instBindingRequired other = True
+instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas)
+instBindingRequired other = True
instCanBeGeneralised :: Inst -> Bool
-instCanBeGeneralised (Dict _ (Class clas _) _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
+instCanBeGeneralised (Dict _ (ClassP clas _) _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
\end{code}
-Construction
-~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Building dictionaries}
+%* *
+%************************************************************************
\begin{code}
newDicts :: InstOrigin
-> TcThetaType
- -> NF_TcM s (LIE, [TcId])
+ -> TcM [Inst]
newDicts orig theta
- = tcGetInstLoc orig `thenNF_Tc` \ loc ->
- newDictsAtLoc loc theta `thenNF_Tc` \ (dicts, ids) ->
- returnNF_Tc (listToBag dicts, ids)
+ = getInstLoc orig `thenM` \ loc ->
+ newDictsAtLoc loc theta
-newClassDicts :: InstOrigin
- -> [(Class,[TcType])]
- -> NF_TcM s (LIE, [TcId])
-newClassDicts orig theta
- = newDicts orig (map (uncurry Class) theta)
+cloneDict :: Inst -> TcM Inst
+cloneDict (Dict id ty loc) = newUnique `thenM` \ uniq ->
+ returnM (Dict (setIdUnique id uniq) ty loc)
+
+newDictsFromOld :: Inst -> TcThetaType -> TcM [Inst]
+newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta
-- Local function, similar to newDicts,
-- but with slightly different interface
newDictsAtLoc :: InstLoc
-> TcThetaType
- -> NF_TcM s ([Inst], [TcId])
-newDictsAtLoc loc theta =
- tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u pred = Dict u pred loc
- dicts = zipWithEqual "newDictsAtLoc" mk_dict new_uniqs theta
- in
- returnNF_Tc (dicts, map instToId dicts)
-
-newDictFromOld :: Inst -> Class -> [TcType] -> NF_TcM s Inst
-newDictFromOld (Dict _ _ loc) clas tys
- = tcGetUnique `thenNF_Tc` \ uniq ->
- returnNF_Tc (Dict uniq (Class clas tys) loc)
-
-
-newMethod :: InstOrigin
- -> TcId
- -> [TcType]
- -> NF_TcM s (LIE, TcId)
-newMethod orig id tys
- = -- Get the Id type and instantiate it at the specified types
+ -> TcM [Inst]
+newDictsAtLoc inst_loc theta
+ = newUniqueSupply `thenM` \ us ->
+ returnM (zipWith mk_dict (uniqsFromSupply us) theta)
+ where
+ mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred))
+ pred inst_loc
+ loc = instLocSrcLoc inst_loc
+
+-- 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
+-- But with splittable implicit parameters there may be many in
+-- scope, so we make up a new name.
+newIPDict :: InstOrigin -> IPName Name -> Type
+ -> TcM (IPName Id, Inst)
+newIPDict orig ip_name ty
+ = getInstLoc orig `thenM` \ inst_loc@(InstLoc _ loc _) ->
+ newUnique `thenM` \ uniq ->
let
- (tyvars, rho) = splitForAllTys (idType id)
- rho_ty = substTy (mkTyVarSubst tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
+ pred = IParam ip_name ty
+ id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)
in
- newMethodWithGivenTy orig id tys theta tau `thenNF_Tc` \ meth_inst ->
- returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
-
-instOverloadedFun orig (HsVar v) arg_tys theta tau
- = newMethodWithGivenTy orig v arg_tys theta tau `thenNF_Tc` \ inst ->
- instFunDeps orig theta `thenNF_Tc` \ fds ->
- returnNF_Tc (HsVar (instToId inst), mkLIE (inst : fds))
-
-instFunDeps orig theta
- = tcGetInstLoc orig `thenNF_Tc` \ loc ->
- let ifd (Class clas tys) =
- let fds = instantiateFdClassTys clas tys in
- if null fds then Nothing else Just (FunDep clas fds loc)
- ifd _ = Nothing
- in returnNF_Tc (catMaybes (map ifd theta))
+ returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc)
+\end{code}
+
+
+
+%************************************************************************
+%* *
+\subsection{Building methods (calls of overloaded functions)}
+%* *
+%************************************************************************
+
+
+\begin{code}
+tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, TcType)
+tcInstCall orig fun_ty -- fun_ty is usually a sigma-type
+ = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ newDicts orig theta `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
+ let
+ inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts)
+ in
+ returnM (mkCoercion inst_fn, tau)
+
+tcInstDataCon :: InstOrigin -> DataCon
+ -> TcM ([TcType], -- Types to instantiate at
+ [Inst], -- Existential dictionaries to apply to
+ [TcType], -- Argument types of constructor
+ TcType, -- Result type
+ [TyVar]) -- Existential tyvars
+tcInstDataCon orig data_con
+ = let
+ (tvs, stupid_theta, ex_tvs, ex_theta, arg_tys, tycon) = dataConSig data_con
+ -- We generate constraints for the stupid theta even when
+ -- pattern matching (as the Report requires)
+ in
+ tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (all_tvs', ty_args', tenv) ->
+ let
+ stupid_theta' = substTheta tenv stupid_theta
+ ex_theta' = substTheta tenv ex_theta
+ arg_tys' = map (substTy tenv) arg_tys
+
+ n_normal_tvs = length tvs
+ ex_tvs' = drop n_normal_tvs all_tvs'
+ result_ty = mkTyConApp tycon (take n_normal_tvs ty_args')
+ in
+ newDicts orig stupid_theta' `thenM` \ stupid_dicts ->
+ newDicts orig ex_theta' `thenM` \ ex_dicts ->
+
+ -- Note that we return the stupid theta *only* in the LIE;
+ -- we don't otherwise use it at all
+ extendLIEs stupid_dicts `thenM_`
+
+ returnM (ty_args', ex_dicts, arg_tys', result_ty, ex_tvs')
+
+newMethodFromName :: InstOrigin -> TcType -> Name -> TcM TcId
+newMethodFromName origin ty name
+ = tcLookupId name `thenM` \ id ->
+ -- Use tcLookupId not tcLookupGlobalId; the method is almost
+ -- always a class op, but with -fno-implicit-prelude GHC is
+ -- meant to find whatever thing is in scope, and that may
+ -- be an ordinary function.
+ getInstLoc origin `thenM` \ loc ->
+ tcInstClassOp loc id [ty] `thenM` \ inst ->
+ extendLIE inst `thenM_`
+ returnM (instToId inst)
newMethodWithGivenTy orig id tys theta tau
- = tcGetInstLoc orig `thenNF_Tc` \ loc ->
- newMethodWith id tys theta tau loc
-
-newMethodWith id tys theta tau loc
- = tcGetUnique `thenNF_Tc` \ new_uniq ->
- returnNF_Tc (Method new_uniq id tys theta tau loc)
-
-newMethodAtLoc :: InstLoc
- -> Id -> [TcType]
- -> NF_TcM s (Inst, TcId)
-newMethodAtLoc loc real_id tys -- Local function, similar to newMethod but with
- -- slightly different interface
- = -- Get the Id type and instantiate it at the specified types
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ = getInstLoc orig `thenM` \ loc ->
+ newMethod loc id tys theta tau `thenM` \ inst ->
+ extendLIE inst `thenM_`
+ returnM (instToId inst)
+
+--------------------------------------------
+-- tcInstClassOp, and newMethod do *not* drop the
+-- Inst into the LIE; they just returns the Inst
+-- This is important because they are used by TcSimplify
+-- to simplify Insts
+
+tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst
+tcInstClassOp inst_loc sel_id tys
+ = let
+ (tyvars,rho) = tcSplitForAllTys (idType sel_id)
+ rho_ty = ASSERT( length tyvars == length tys )
+ substTyWith tyvars tys rho
+ (preds,tau) = tcSplitPhiTy rho_ty
+ in
+ newMethod inst_loc sel_id tys preds tau
+
+---------------------------
+newMethod inst_loc id tys theta tau
+ = newUnique `thenM` \ new_uniq ->
let
- (tyvars,rho) = splitForAllTys (idType real_id)
- rho_ty = ASSERT( length tyvars == length tys )
- substTy (mkTopTyVarSubst tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
- meth_inst = Method new_uniq real_id tys theta tau loc
+ meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc
+ inst = Method meth_id id tys theta tau inst_loc
+ loc = instLocSrcLoc inst_loc
in
- returnNF_Tc (meth_inst, instToId meth_inst)
+ returnM inst
\end{code}
In newOverloadedLit we convert directly to an Int or Integer if we
\begin{code}
newOverloadedLit :: InstOrigin
- -> OverloadedLit
+ -> HsOverLit
-> TcType
- -> NF_TcM s (TcExpr, LIE)
-newOverloadedLit orig (OverloadedIntegral i) ty
- | isIntTy ty && inIntRange i -- Short cut for Int
- = returnNF_Tc (int_lit, emptyLIE)
-
- | isIntegerTy ty -- Short cut for Integer
- = returnNF_Tc (integer_lit, emptyLIE)
-
- where
- intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
- integer_lit = HsLitOut (HsInt i) integerTy
- int_lit = HsCon intDataCon [] [intprim_lit]
-
-newOverloadedLit orig lit ty -- The general case
- = tcGetInstLoc orig `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ -> TcM TcExpr
+newOverloadedLit orig lit@(HsIntegral i fi) expected_ty
+ | fi /= fromIntegerName -- Do not generate a LitInst for rebindable
+ -- syntax. Reason: tcSyntaxName does unification
+ -- which is very inconvenient in tcSimplify
+ = tcSyntaxName orig expected_ty (fromIntegerName, HsVar fi) `thenM` \ (_,expr) ->
+ returnM (HsApp expr (HsLit (HsInteger i)))
+
+ | Just expr <- shortCutIntLit i expected_ty
+ = returnM expr
+
+ | otherwise
+ = newLitInst orig lit expected_ty
+
+newOverloadedLit orig lit@(HsFractional r fr) expected_ty
+ | fr /= fromRationalName -- c.f. HsIntegral case
+ = tcSyntaxName orig expected_ty (fromRationalName, HsVar fr) `thenM` \ (_,expr) ->
+ mkRatLit r `thenM` \ rat_lit ->
+ returnM (HsApp expr rat_lit)
+
+ | Just expr <- shortCutFracLit r expected_ty
+ = returnM expr
+
+ | otherwise
+ = newLitInst orig lit expected_ty
+
+newLitInst orig lit expected_ty
+ = getInstLoc orig `thenM` \ loc ->
+ newUnique `thenM` \ new_uniq ->
let
- lit_inst = LitInst new_uniq lit ty loc
+ lit_inst = LitInst lit_id lit expected_ty loc
+ lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty
in
- returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst)
-\end{code}
-
-\begin{code}
-newIPDict name ty loc
- = tcGetUnique `thenNF_Tc` \ new_uniq ->
- let d = Dict new_uniq (IParam name ty) loc in
- returnNF_Tc d
+ extendLIE lit_inst `thenM_`
+ returnM (HsVar (instToId lit_inst))
+
+shortCutIntLit :: Integer -> TcType -> Maybe TcExpr
+shortCutIntLit i ty
+ | isIntTy ty && inIntRange i -- Short cut for Int
+ = Just (HsLit (HsInt i))
+ | isIntegerTy ty -- Short cut for Integer
+ = Just (HsLit (HsInteger i))
+ | otherwise = Nothing
+
+shortCutFracLit :: Rational -> TcType -> Maybe TcExpr
+shortCutFracLit f ty
+ | isFloatTy ty
+ = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)])
+ | isDoubleTy ty
+ = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)])
+ | otherwise = Nothing
+
+mkRatLit :: Rational -> TcM TcExpr
+mkRatLit r
+ = tcLookupTyCon rationalTyConName `thenM` \ rat_tc ->
+ let
+ rational_ty = mkGenTyConApp rat_tc []
+ in
+ returnM (HsLit (HsRat r rational_ty))
\end{code}
-\begin{code}
-instToId :: Inst -> TcId
-instToId inst = instToIdBndr inst
-
-instToIdBndr :: Inst -> TcId
-instToIdBndr (Dict u (Class clas ty) (_,loc,_))
- = mkUserLocal (mkDictOcc (getOccName clas)) u (mkDictTy clas ty) loc
-instToIdBndr (Dict u (IParam n ty) (_,loc,_))
--- = mkUserLocal (mkIPOcc (getOccName n)) u (mkPredTy (IParam n ty)) loc
- = mkUserLocal (getOccName n) (nameUnique n) (mkPredTy (IParam n ty)) loc
--- = mkVanillaId n ty
-
-instToIdBndr (Method u id tys theta tau (_,loc,_))
- = mkUserLocal (mkMethodOcc (getOccName id)) u tau loc
-
-instToIdBndr (LitInst u list ty loc)
- = mkSysLocal SLIT("lit") u ty
-
-instToIdBndr (FunDep clas fds _)
- = panic "FunDep escaped!!!"
-\end{code}
+%************************************************************************
+%* *
+\subsection{Zonking}
+%* *
+%************************************************************************
-Zonking
-~~~~~~~
Zonking makes sure that the instance types are fully zonked,
-but doesn't do the same for the Id in a Method. There's no
+but doesn't do the same for any of the Ids in an Inst. There's no
need, and it's a lot of extra work.
\begin{code}
-zonkPred :: TcPredType -> NF_TcM s TcPredType
-zonkPred (Class clas tys)
- = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
- returnNF_Tc (Class clas new_tys)
-zonkPred (IParam n ty)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (IParam n new_ty)
-
-zonkInst :: Inst -> NF_TcM s Inst
-zonkInst (Dict u pred loc)
- = zonkPred pred `thenNF_Tc` \ new_pred ->
- returnNF_Tc (Dict u new_pred loc)
-
-zonkInst (Method u id tys theta tau loc)
- = zonkId id `thenNF_Tc` \ new_id ->
+zonkInst :: Inst -> TcM Inst
+zonkInst (Dict id pred loc)
+ = zonkTcPredType pred `thenM` \ new_pred ->
+ returnM (Dict id new_pred loc)
+
+zonkInst (Method m id tys theta tau loc)
+ = 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
-- an InstId, in which case it won't be in scope
- zonkTcTypes tys `thenNF_Tc` \ new_tys ->
- zonkTcThetaType theta `thenNF_Tc` \ new_theta ->
- zonkTcType tau `thenNF_Tc` \ new_tau ->
- returnNF_Tc (Method u new_id new_tys new_theta new_tau loc)
-
-zonkInst (LitInst u lit ty loc)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (LitInst u lit new_ty loc)
+ zonkTcTypes tys `thenM` \ new_tys ->
+ zonkTcThetaType theta `thenM` \ new_theta ->
+ zonkTcType tau `thenM` \ new_tau ->
+ returnM (Method m new_id new_tys new_theta new_tau loc)
-zonkInst (FunDep clas fds loc)
- = zonkFunDeps fds `thenNF_Tc` \ fds' ->
- returnNF_Tc (FunDep clas fds' loc)
+zonkInst (LitInst id lit ty loc)
+ = zonkTcType ty `thenM` \ new_ty ->
+ returnM (LitInst id lit new_ty loc)
-zonkFunDeps fds = mapNF_Tc zonkFd fds
- where
- zonkFd (ts1, ts2)
- = zonkTcTypes ts1 `thenNF_Tc` \ ts1' ->
- zonkTcTypes ts2 `thenNF_Tc` \ ts2' ->
- returnNF_Tc (ts1', ts2')
-
-zonkTvFunDeps fds = mapNF_Tc zonkFd fds
- where
- zonkFd (tvs1, tvs2)
- = zonkTcTyVars tvs1 `thenNF_Tc` \ tvs1' ->
- zonkTcTyVars tvs2 `thenNF_Tc` \ tvs2' ->
- returnNF_Tc (tvs1', tvs2')
+zonkInsts insts = mappM zonkInst insts
\end{code}
-Printing
-~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Printing}
+%* *
+%************************************************************************
+
ToDo: improve these pretty-printing things. The ``origin'' is really only
relevant in error messages.
instance Outputable Inst where
ppr inst = pprInst inst
+pprInsts :: [Inst] -> SDoc
+pprInsts insts = parens (sep (punctuate comma (map pprInst insts)))
+
+pprInstsInFull insts
+ = vcat (map go insts)
+ where
+ go inst = sep [quotes (ppr inst), nest 2 (pprInstLoc (instLoc inst))]
+
pprInst (LitInst u lit ty loc)
- = hsep [case lit of
- OverloadedIntegral i -> integer i
- OverloadedFractional f -> rational f,
- ptext SLIT("at"),
- ppr ty,
- show_uniq u]
+ = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u]
pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u
-pprInst (Method u id tys _ _ loc)
+pprInst m@(Method u id tys theta tau loc)
= hsep [ppr id, ptext SLIT("at"),
- brackets (interppSP tys),
- show_uniq u]
-
-pprInst (FunDep clas fds loc)
- = hsep [ppr clas, ppr fds]
-
-tidyPred :: TidyEnv -> TcPredType -> (TidyEnv, TcPredType)
-tidyPred env (Class clas tys)
- = (env', Class clas tys')
- where
- (env', tys') = tidyOpenTypes env tys
-tidyPred env (IParam n ty)
- = (env', IParam n ty')
- where
- (env', ty') = tidyOpenType env ty
+ brackets (sep (map pprParendType tys)) {- ,
+ ptext SLIT("theta"), ppr theta,
+ ptext SLIT("tau"), ppr tau
+ show_uniq u,
+ ppr (instToId m) -}]
-tidyInst :: TidyEnv -> Inst -> (TidyEnv, Inst)
-tidyInst env (LitInst u lit ty loc)
- = (env', LitInst u lit ty' loc)
- where
- (env', ty') = tidyOpenType env ty
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
-tidyInst env (Dict u pred loc)
- = (env', Dict u pred' loc)
- where
- (env', pred') = tidyPred env pred
+tidyInst :: TidyEnv -> Inst -> Inst
+tidyInst env (LitInst u lit ty loc) = LitInst u lit (tidyType env ty) loc
+tidyInst env (Dict u pred loc) = Dict u (tidyPred env pred) loc
+tidyInst env (Method u id tys theta tau loc) = Method u id (tidyTypes env tys) theta tau loc
-tidyInst env (Method u id tys theta tau loc)
- = (env', Method u id tys' theta tau loc)
- -- Leave theta, tau alone cos we don't print them
+tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst])
+-- This function doesn't assume that the tyvars are in scope
+-- so it works like tidyOpenType, returning a TidyEnv
+tidyMoreInsts env insts
+ = (env', map (tidyInst env') insts)
where
- (env', tys') = tidyOpenTypes env tys
-
--- this case shouldn't arise... (we never print fundeps)
-tidyInst env fd@(FunDep clas fds loc)
- = (env, fd)
+ env' = tidyFreeTyVars env (tyVarsOfInsts insts)
-tidyInsts env insts = mapAccumL tidyInst env insts
+tidyInsts :: [Inst] -> (TidyEnv, [Inst])
+tidyInsts insts = tidyMoreInsts emptyTidyEnv insts
-show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
+showLIE :: SDoc -> TcM () -- Debugging
+showLIE str
+ = do { lie_var <- getLIEVar ;
+ lie <- readMutVar lie_var ;
+ traceTc (str <+> pprInstsInFull (lieToList lie)) }
\end{code}
%************************************************************************
%* *
-\subsection[InstEnv-types]{Type declarations}
+\subsection{Looking up Insts}
%* *
%************************************************************************
\begin{code}
-type InstanceMapper = Class -> InstEnv
-\end{code}
-
-A @ClassInstEnv@ lives inside a class, and identifies all the instances
-of that class. The @Id@ inside a ClassInstEnv mapping is the dfun for
-that instance.
-
-There is an important consistency constraint between the @MatchEnv@s
-in and the dfun @Id@s inside them: the free type variables of the
-@Type@ key in the @MatchEnv@ must be a subset of the universally-quantified
-type variables of the dfun. Thus, the @ClassInstEnv@ for @Eq@ might
-contain the following entry:
-@
- [a] ===> dfun_Eq_List :: forall a. Eq a => Eq [a]
-@
-The "a" in the pattern must be one of the forall'd variables in
-the dfun type.
-
-\begin{code}
data LookupInstResult s
= NoInstance
| SimpleInst TcExpr -- Just a variable, type application, or literal
| GenInst [Inst] TcExpr -- The expression and its needed insts
-lookupInst :: Inst
- -> NF_TcM s (LookupInstResult s)
+lookupInst :: Inst -> TcM (LookupInstResult s)
+-- 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
--- Dictionaries
-lookupInst dict@(Dict _ (Class clas tys) loc)
- = case lookupInstEnv (ppr clas) (classInstEnv clas) tys of
-
- Just (tenv, dfun_id)
- -> let
- subst = mkSubst (tyVarsOfTypes tys) tenv
- (tyvars, rho) = splitForAllTys (idType dfun_id)
- ty_args = map subst_tv tyvars
- dfun_rho = substTy subst rho
- (theta, tau) = splitRhoTy dfun_rho
- ty_app = mkHsTyApp (HsVar dfun_id) ty_args
- subst_tv tv = case lookupSubstEnv tenv tv of
- Just (DoneTy ty) -> ty
- -- tenv should bind all the tyvars
+-- Dictionaries
+lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
+ = getDOpts `thenM` \ dflags ->
+ tcGetInstEnv `thenM` \ inst_env ->
+ case lookupInstEnv dflags inst_env clas tys of
+
+ FoundInst tenv dfun_id
+ -> -- It's possible that not all the tyvars are in
+ -- the substitution, tenv. For example:
+ -- instance C X a => D X where ...
+ -- (presumably there's a functional dependency in class C)
+ -- Hence the mk_ty_arg to instantiate any un-substituted tyvars.
+ getStage `thenM` \ use_stage ->
+ checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred))
+ (topIdLvl dfun_id) use_stage `thenM_`
+ traceTc (text "lookupInst" <+> ppr dfun_id <+> ppr (topIdLvl dfun_id) <+> ppr use_stage) `thenM_`
+ let
+ (tyvars, rho) = tcSplitForAllTys (idType dfun_id)
+ mk_ty_arg tv = case lookupSubstEnv tenv tv of
+ Just (DoneTy ty) -> returnM ty
+ Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv ->
+ returnM (mkTyVarTy tc_tv)
+ in
+ mappM mk_ty_arg tyvars `thenM` \ ty_args ->
+ let
+ dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho
+ (theta, _) = tcSplitPhiTy dfun_rho
+ ty_app = mkHsTyApp (HsVar dfun_id) ty_args
in
if null theta then
- returnNF_Tc (SimpleInst ty_app)
+ returnM (SimpleInst ty_app)
else
- newDictsAtLoc loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
+ newDictsAtLoc loc theta `thenM` \ dicts ->
let
- rhs = mkHsDictApp ty_app dict_ids
+ rhs = mkHsDictApp ty_app (map instToId dicts)
in
- returnNF_Tc (GenInst dicts rhs)
+ returnM (GenInst dicts rhs)
+
+ other -> returnM NoInstance
- Nothing -> returnNF_Tc NoInstance
-lookupInst dict@(Dict _ _ loc) = returnNF_Tc NoInstance
+lookupInst (Dict _ _ _) = returnM NoInstance
-- Methods
lookupInst inst@(Method _ id tys theta _ loc)
- = newDictsAtLoc loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
+ = newDictsAtLoc loc theta `thenM` \ dicts ->
+ returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts)))
-- Literals
-lookupInst inst@(LitInst u (OverloadedIntegral i) ty loc)
- | isIntTy ty && in_int_range -- Short cut for Int
- = returnNF_Tc (GenInst [] int_lit)
- -- GenInst, not SimpleInst, because int_lit is actually a constructor application
+-- 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 u (HsIntegral i from_integer_name) ty loc)
+ | Just expr <- shortCutIntLit i ty
+ = returnM (GenInst [] expr) -- GenInst, not SimpleInst, because
+ -- expr may be a constructor application
+ | otherwise
+ = ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant
+ tcLookupId fromIntegerName `thenM` \ from_integer ->
+ tcInstClassOp loc from_integer [ty] `thenM` \ method_inst ->
+ returnM (GenInst [method_inst]
+ (HsApp (HsVar (instToId method_inst)) (HsLit (HsInteger i))))
+
+
+lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc)
+ | Just expr <- shortCutFracLit f ty
+ = returnM (GenInst [] expr)
+
+ | otherwise
+ = ASSERT( from_rat_name == fromRationalName ) -- A LitInst invariant
+ tcLookupId fromRationalName `thenM` \ from_rational ->
+ tcInstClassOp loc from_rational [ty] `thenM` \ method_inst ->
+ mkRatLit f `thenM` \ rat_lit ->
+ returnM (GenInst [method_inst] (HsApp (HsVar (instToId method_inst)) rat_lit))
+\end{code}
- | isIntegerTy ty -- Short cut for Integer
- = returnNF_Tc (GenInst [] integer_lit)
- | in_int_range -- It's overloaded but small enough to fit into an Int
- = tcLookupValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int ->
- newMethodAtLoc loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) int_lit))
- | otherwise -- Alas, it is overloaded and a big literal!
- = tcLookupValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
- newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) integer_lit))
- where
- in_int_range = inIntRange i
- intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
- integer_lit = HsLitOut (HsInt i) integerTy
- int_lit = HsCon intDataCon [] [intprim_lit]
+%************************************************************************
+%* *
+ Re-mappable syntax
+%* *
+%************************************************************************
--- similar idea for overloaded floating point literals: if the literal is
--- *definitely* a float or a double, generate the real thing here.
--- This is essential (see nofib/spectral/nucleic).
-lookupInst inst@(LitInst u (OverloadedFractional f) ty loc)
- | isFloatTy ty = returnNF_Tc (GenInst [] float_lit)
- | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit)
+Suppose we are doing the -fno-implicit-prelude thing, and we encounter
+a do-expression. We have to find (>>) in the current environment, which is
+done by the rename. Then we have to check that it has the same type as
+Control.Monad.(>>). Or, more precisely, a compatible type. One 'customer' had
+this:
- | otherwise
- = tcLookupValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
+ (>>) :: HB m n mn => m a -> n b -> mn b
- -- The type Rational isn't wired in so we have to conjure it up
- tcLookupTyConByKey rationalTyConKey `thenNF_Tc` \ rational_tycon ->
- let
- rational_ty = mkSynTy rational_tycon []
- rational_lit = HsLitOut (HsFrac f) rational_ty
- in
- newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
+So the idea is to generate a local binding for (>>), thus:
- where
- floatprim_lit = HsLitOut (HsFloatPrim f) floatPrimTy
- float_lit = HsCon floatDataCon [] [floatprim_lit]
- doubleprim_lit = HsLitOut (HsDoublePrim f) doublePrimTy
- double_lit = HsCon doubleDataCon [] [doubleprim_lit]
+ let then72 :: forall a b. m a -> m b -> m b
+ then72 = ...something involving the user's (>>)...
+ in
+ ...the do-expression...
--- there are no `instances' of functional dependencies or implicit params
+Now the do-expression can proceed using then72, which has exactly
+the expected type.
-lookupInst _ = returnNF_Tc NoInstance
+In fact tcSyntaxName just generates the RHS for then72, because we only
+want an actual binding in the do-expression case. For literals, we can
+just use the expression inline.
-\end{code}
+\begin{code}
+tcSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> (Name, HsExpr Name) -- (Standard name, user name)
+ -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
+
+-- NB: tcSyntaxName calls tcExpr, and hence can do unification.
+-- So we do not call it from lookupInst, which is called from tcSimplify
+
+tcSyntaxName orig ty (std_nm, HsVar user_nm)
+ | std_nm == user_nm
+ = tcStdSyntaxName orig ty std_nm
+
+tcSyntaxName orig ty (std_nm, user_nm_expr)
+ = tcLookupId std_nm `thenM` \ std_id ->
+ let
+ -- C.f. newMethodAtLoc
+ ([tv], _, tau) = tcSplitSigmaTy (idType std_id)
+ tau1 = substTyWith [tv] [ty] tau
+ -- Actually, the "tau-type" might be a sigma-type in the
+ -- case of locally-polymorphic methods.
+ in
+ addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $
+ tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
+ returnM (std_nm, expr)
-There is a second, simpler interface, when you want an instance of a
-class at a given nullary type constructor. It just returns the
-appropriate dictionary if it exists. It is used only when resolving
-ambiguous dictionaries.
+tcStdSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> Name -- Standard name
+ -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
-\begin{code}
-lookupSimpleInst :: InstEnv
- -> Class
- -> [Type] -- Look up (c,t)
- -> NF_TcM s (Maybe [(Class,[Type])]) -- Here are the needed (c,t)s
-
-lookupSimpleInst class_inst_env clas tys
- = case lookupInstEnv (ppr clas) class_inst_env tys of
- Nothing -> returnNF_Tc Nothing
-
- Just (tenv, dfun)
- -> returnNF_Tc (Just (substClasses (mkSubst emptyInScopeSet tenv) theta'))
- where
- (_, theta, _) = splitSigmaTy (idType dfun)
- theta' = map (\(Class clas tys) -> (clas,tys)) theta
+tcStdSyntaxName orig ty std_nm
+ = newMethodFromName orig ty std_nm `thenM` \ id ->
+ returnM (std_nm, HsVar id)
+
+syntaxNameCtxt name orig ty tidy_env
+ = getInstLoc orig `thenM` \ inst_loc ->
+ let
+ 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)]
+ in
+ returnM (tidy_env, msg)
\end{code}
projects / ghc-hetmet.git / blobdiff