\section[Inst]{The @Inst@ type: dictionaries or method instances}
\begin{code}
-module Inst (
- LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE,
- plusLIEs, mkLIE, isEmptyLIE,
+module Inst (
+ showLIE,
- Inst, OverloadedLit(..),
- pprInst, pprInsts, pprInstsInFull, tidyInst, tidyInsts,
+ Inst,
+ pprInst, pprInsts, pprInstsInFull, pprDFuns,
+ tidyInsts, tidyMoreInsts,
- InstanceMapper,
+ newDictsFromOld, newDicts, cloneDict,
+ newOverloadedLit, newIPDict,
+ newMethod, newMethodFromName, newMethodWithGivenTy,
+ tcInstClassOp, tcInstCall, tcInstDataCon,
+ tcSyntaxName, tcStdSyntaxName,
- newDictFromOld, newDicts, newDictsAtLoc,
- newMethod, newMethodWithGivenTy, newOverloadedLit,
+ tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
+ ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
+ instLoc, getDictClassTys, dictPred,
- tyVarsOfInst, instLoc, getDictClassTys,
+ lookupInst, LookupInstResult(..),
+ tcExtendLocalInstEnv, tcGetInstEnvs,
- lookupInst, lookupSimpleInst, LookupInstResult(..),
+ isDict, isClassDict, isMethod,
+ isLinearInst, linearInstType, isIPDict, isInheritableInst,
+ isTyVarDict, isStdClassTyVarDict, isMethodFor,
+ instBindingRequired,
- isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor,
- instBindingRequired, instCanBeGeneralised,
+ zonkInst, zonkInsts,
+ instToId, instName,
- zonkInst, instToId, instToIdBndr,
-
- InstOrigin(..), pprOrigin
+ InstOrigin(..), InstLoc(..), pprInstLoc
) where
#include "HsVersions.h"
-import HsSyn ( HsLit(..), HsExpr(..) )
-import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr, RenamedPat )
-import TcHsSyn ( TcExpr, TcId,
- mkHsTyApp, mkHsDictApp, zonkId
- )
-import TcMonad
-import TcEnv ( TcIdSet, tcLookupValueByKey, tcLookupTyConByKey )
-import TcType ( TcThetaType,
- TcType, TcTauType, TcTyVarSet,
- zonkTcType, zonkTcTypes,
- zonkTcThetaType
- )
-import Bag
-import Class ( classInstEnv,
- Class, ClassInstEnv
+import {-# SOURCE #-} TcExpr( tcCheckSigma )
+
+import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp )
+import TcHsSyn ( TcId, TcIdSet,
+ mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId,
+ mkCoercion, ExprCoFn
)
-import Id ( Id, idFreeTyVars, idType, mkUserLocal, mkSysLocal )
-import VarSet ( elemVarSet )
-import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
-import Name ( OccName, Name, mkDictOcc, mkMethodOcc, getOccName )
-import PprType ( pprConstraint )
-import SpecEnv ( SpecEnv, lookupSpecEnv )
-import SrcLoc ( SrcLoc )
-import Type ( Type, ThetaType, substTy,
- isTyVarTy, mkDictTy, splitForAllTys, splitSigmaTy,
- splitRhoTy, tyVarsOfType, tyVarsOfTypes,
- mkSynTy, substTopTy, substTopTheta,
- tidyOpenType, tidyOpenTypes
+import TcRnMonad
+import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy )
+import InstEnv ( DFunId, InstEnv, lookupInstEnv, checkFunDeps, extendInstEnv )
+import TcIface ( loadImportedInsts )
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
+ zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
-import TyCon ( TyCon )
-import VarEnv ( zipVarEnv, lookupVarEnv, TidyEnv )
-import VarSet ( 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 TcType ( Type, TcType, TcThetaType, TcTyVarSet,
+ PredType(..), TyVarDetails(VanillaTv),
+ tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
+ tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy,
+ isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
+ tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
+ tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
+ isClassPred, isTyVarClassPred, isLinearPred,
+ getClassPredTys, getClassPredTys_maybe, mkPredName,
+ isInheritablePred, isIPPred, matchTys,
+ tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
+ pprPred, pprParendType, pprThetaArrow, pprClassPred
)
-import Maybes ( expectJust )
-import Util ( thenCmp, zipWithEqual, mapAccumL )
+import HscTypes ( ExternalPackageState(..) )
+import CoreFVs ( idFreeTyVars )
+import DataCon ( DataCon,dataConSig )
+import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique )
+import PrelInfo ( isStandardClass, isNoDictClass )
+import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, isHomePackageName, isInternalName )
+import NameSet ( addOneToNameSet )
+import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst )
+import Literal ( inIntRange )
+import Var ( TyVar )
+import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) )
+import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet )
+import TysWiredIn ( floatDataCon, doubleDataCon )
+import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName )
+import BasicTypes( IPName(..), mapIPName, ipNameName )
+import UniqSupply( uniqsFromSupply )
+import SrcLoc ( mkSrcSpan, noLoc, Located(..) )
+import CmdLineOpts( DynFlags, DynFlag( Opt_AllowUndecidableInstances ), dopt )
+import Maybes ( isJust )
import Outputable
\end{code}
-%************************************************************************
-%* *
-\subsection[Inst-collections]{LIE: a collection of Insts}
-%* *
-%************************************************************************
+Selection
+~~~~~~~~~
\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
-
-zonkLIE :: LIE -> NF_TcM s LIE
-zonkLIE lie = mapBagNF_Tc zonkInst lie
-
-pprInsts :: [Inst] -> SDoc
-pprInsts insts = parens (hsep (punctuate comma (map pprInst insts)))
-
-
-pprInstsInFull insts
- = vcat (map go insts)
- where
- go inst = quotes (ppr inst) <+> pprOrigin inst
-\end{code}
+instName :: Inst -> Name
+instName inst = idName (instToId inst)
-%************************************************************************
-%* *
-\subsection[Inst-types]{@Inst@ types}
-%* *
-%************************************************************************
+instToId :: Inst -> TcId
+instToId (Dict id _ _) = id
+instToId (Method id _ _ _ _ _) = id
+instToId (LitInst id _ _ _) = id
-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
+instLoc (Dict _ _ loc) = loc
+instLoc (Method _ _ _ _ _ loc) = loc
+instLoc (LitInst _ _ _ loc) = loc
- Method 34 doubleId [Int] origin
+dictPred (Dict _ pred _ ) = pred
+dictPred inst = pprPanic "dictPred" (ppr inst)
-\begin{code}
-data Inst
- = Dict
- Unique
- Class -- The type of the dict is (c ts), where
- [TcType] -- c is the class and ts the types;
- InstOrigin
- SrcLoc
-
- | 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
-
- InstOrigin
- SrcLoc
-
- -- 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
- InstOrigin -- Always a literal; but more convenient to carry this around
- SrcLoc
-
-data OverloadedLit
- = OverloadedIntegral Integer -- The number
- | OverloadedFractional Rational -- The number
-\end{code}
+getDictClassTys (Dict _ pred _) = getClassPredTys pred
-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.
+-- 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
-\begin{code}
-instance Ord Inst where
- compare = cmpInst
-
-instance Eq Inst where
- (==) i1 i2 = case i1 `cmpInst` i2 of
- EQ -> True
- other -> False
-
-cmpInst (Dict _ clas1 tys1 _ _) (Dict _ clas2 tys2 _ _)
- = (clas1 `compare` clas2) `thenCmp` (tys1 `compare` tys2)
-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 _ _ _ _ _) other
- = 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}
+fdPredsOfInsts :: [Inst] -> [PredType]
+fdPredsOfInsts insts = concatMap fdPredsOfInst insts
+isInheritableInst (Dict _ pred _) = isInheritablePred pred
+isInheritableInst (Method _ _ _ theta _ _) = all isInheritablePred theta
+isInheritableInst other = True
-Selection
-~~~~~~~~~
-\begin{code}
-instOrigin (Dict u clas tys origin loc) = origin
-instOrigin (Method u clas ty _ _ origin loc) = origin
-instOrigin (LitInst u lit ty origin loc) = origin
-instLoc (Dict u clas tys origin loc) = loc
-instLoc (Method u clas ty _ _ origin loc) = loc
-instLoc (LitInst u lit ty origin loc) = loc
+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]
-getDictClassTys (Dict u clas tys _ _) = (clas, tys)
+ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n]
+ipNamesOfInst (Method _ _ _ theta _ _) = [ipNameName n | IParam n _ <- theta]
+ipNamesOfInst other = []
tyVarsOfInst :: Inst -> TcTyVarSet
-tyVarsOfInst (Dict _ _ tys _ _) = tyVarsOfTypes tys
-tyVarsOfInst (Method _ id tys _ _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
+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
+
+
+tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
+tyVarsOfLIE lie = tyVarsOfInsts (lieToList lie)
\end{code}
Predicates
~~~~~~~~~~
\begin{code}
isDict :: Inst -> Bool
-isDict (Dict _ _ _ _ _) = True
-isDict other = False
+isDict (Dict _ _ _) = True
+isDict other = False
-isMethodFor :: TcIdSet -> Inst -> Bool
-isMethodFor ids (Method uniq id tys _ _ orig loc)
- = id `elemVarSet` ids
-isMethodFor ids inst
- = False
+isClassDict :: Inst -> Bool
+isClassDict (Dict _ pred _) = isClassPred pred
+isClassDict other = False
isTyVarDict :: Inst -> Bool
-isTyVarDict (Dict _ _ 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
-isStdClassTyVarDict (Dict _ clas [ty] _ _) = isStandardClass clas && isTyVarTy ty
-isStdClassTyVarDict 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 _ 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 _ clas _ _ _) = not (isNoDictClass clas)
-instBindingRequired other = True
-
-instCanBeGeneralised :: Inst -> Bool
-instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
+instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas)
+instBindingRequired other = True
\end{code}
-Construction
-~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Building dictionaries}
+%* *
+%************************************************************************
\begin{code}
newDicts :: InstOrigin
-> TcThetaType
- -> NF_TcM s (LIE, [TcId])
+ -> TcM [Inst]
newDicts orig theta
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, ids) ->
- returnNF_Tc (listToBag dicts, ids)
+ = getInstLoc orig `thenM` \ loc ->
+ newDictsAtLoc loc 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 :: InstOrigin
- -> SrcLoc
+newDictsAtLoc :: InstLoc
-> TcThetaType
- -> NF_TcM s ([Inst], [TcId])
-newDictsAtLoc orig loc theta =
- tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, tys) = Dict u clas tys orig 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 _ _ _ orig loc) clas tys
- = tcGetUnique `thenNF_Tc` \ uniq ->
- returnNF_Tc (Dict uniq clas tys orig 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 ->
+ newUnique `thenM` \ uniq ->
let
- (tyvars, rho) = splitForAllTys (idType id)
- rho_ty = substTy (zipVarEnv tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
+ pred = IParam ip_name ty
+ name = mkPredName uniq (instLocSrcLoc inst_loc) pred
+ id = mkLocalId name (mkPredTy pred)
in
- newMethodWithGivenTy orig id tys theta tau `thenNF_Tc` \ meth_inst ->
- returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
+ returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc)
+\end{code}
-newMethodWithGivenTy orig id tys theta tau
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+
+%************************************************************************
+%* *
+\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
- meth_inst = Method new_uniq id tys theta tau orig loc
+ inst_fn e = DictApp (mkHsTyApp (noLoc 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
- returnNF_Tc meth_inst
-
-newMethodAtLoc :: InstOrigin -> SrcLoc
- -> Id -> [TcType]
- -> NF_TcM s (Inst, TcId)
-newMethodAtLoc orig 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 ->
+ tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (all_tvs', ty_args', tenv) ->
let
- (tyvars,rho) = splitForAllTys (idType real_id)
- rho_ty = ASSERT( length tyvars == length tys )
- substTopTy (zipVarEnv tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
- meth_inst = Method new_uniq real_id tys theta tau orig loc
+ 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
- returnNF_Tc (meth_inst, instToId meth_inst)
+ 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
+ = 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
+ 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
+ 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
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ -> TcM (LHsExpr TcId)
+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
+ -- ToDo: noLoc sadness
+ = tcSyntaxName orig expected_ty (fromIntegerName, noLoc (HsVar fi)) `thenM` \ (_,expr) ->
+ mkIntegerLit i `thenM` \ integer_lit ->
+ returnM (mkHsApp expr integer_lit)
+
+ | 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, noLoc (HsVar fr)) `thenM` \ (_,expr) ->
+ mkRatLit r `thenM` \ rat_lit ->
+ returnM (mkHsApp expr rat_lit)
+
+ | Just expr <- shortCutFracLit r expected_ty
+ = returnM expr
+
+ | otherwise
+ = newLitInst orig lit expected_ty
+
+newLitInst :: InstOrigin -> HsOverLit -> TcType -> TcM (LHsExpr TcId)
+newLitInst orig lit expected_ty
+ = getInstLoc orig `thenM` \ loc ->
+ newUnique `thenM` \ new_uniq ->
let
- lit_inst = LitInst new_uniq lit ty orig 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}
+ extendLIE lit_inst `thenM_`
+ returnM (L (instLocSrcSpan loc) (HsVar (instToId lit_inst)))
-
-\begin{code}
-instToId :: Inst -> TcId
-instToId inst = instToIdBndr inst
-
-instToIdBndr :: Inst -> TcId
-instToIdBndr (Dict u clas ty orig loc)
- = mkUserLocal (mkDictOcc (getOccName clas)) u (mkDictTy clas ty) loc
-
-instToIdBndr (Method u id tys theta tau orig loc)
- = mkUserLocal (getOccName id) u tau loc
- -- We used to call mkMethodOcc here, but that gives rise to bad
- -- error messages when we print the function name or pattern
- -- of an instance-decl binding. Why? Because the binding is zapped
- -- to use the method name in place of the selector name.
- -- The way it is now, -ddump-xx output may look confusing, but
- -- you can always say -dppr-debug to get the uniques
-
-instToIdBndr (LitInst u list ty orig loc)
- = mkSysLocal SLIT("lit") u ty
+shortCutIntLit :: Integer -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-)
+shortCutIntLit i ty
+ | isIntTy ty && inIntRange i -- Short cut for Int
+ = Just (noLoc (HsLit (HsInt i)))
+ | isIntegerTy ty -- Short cut for Integer
+ = Just (noLoc (HsLit (HsInteger i ty)))
+ | otherwise = Nothing
+
+shortCutFracLit :: Rational -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-)
+shortCutFracLit f ty
+ | isFloatTy ty
+ = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)])
+ | isDoubleTy ty
+ = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)])
+ | otherwise = Nothing
+
+mkIntegerLit :: Integer -> TcM (LHsExpr TcId)
+mkIntegerLit i
+ = tcMetaTy integerTyConName `thenM` \ integer_ty ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsInteger i integer_ty))
+
+mkRatLit :: Rational -> TcM (LHsExpr TcId)
+mkRatLit r
+ = tcMetaTy rationalTyConName `thenM` \ rat_ty ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsRat r rat_ty))
\end{code}
-Zonking
-~~~~~~~
+%************************************************************************
+%* *
+\subsection{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}
-zonkInst :: Inst -> NF_TcM s Inst
-zonkInst (Dict u clas tys orig loc)
- = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
- returnNF_Tc (Dict u clas new_tys orig loc)
+zonkInst :: Inst -> TcM Inst
+zonkInst (Dict id pred loc)
+ = zonkTcPredType pred `thenM` \ new_pred ->
+ returnM (Dict id new_pred loc)
-zonkInst (Method u id tys theta tau orig loc)
- = zonkId id `thenNF_Tc` \ new_id ->
+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 orig 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 (LitInst u lit ty orig loc)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (LitInst u lit new_ty orig loc)
+zonkInst (LitInst id lit ty loc)
+ = zonkTcType ty `thenM` \ new_ty ->
+ returnM (LitInst id lit new_ty loc)
+
+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
-pprInst (LitInst u lit ty orig loc)
- = hsep [case lit of
- OverloadedIntegral i -> integer i
- OverloadedFractional f -> rational f,
- ptext SLIT("at"),
- ppr ty,
- show_uniq u]
+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 (Dict u clas tys orig loc) = pprConstraint clas tys <+> show_uniq u
+pprInst (LitInst u lit ty loc)
+ = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u]
-pprInst (Method u id tys _ _ orig loc)
+pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u
+
+pprInst m@(Method u id tys theta tau loc)
= hsep [ppr id, ptext SLIT("at"),
- brackets (interppSP tys),
- show_uniq u]
+ brackets (sep (map pprParendType tys)) {- ,
+ ptext SLIT("theta"), ppr theta,
+ ptext SLIT("tau"), ppr tau
+ show_uniq u,
+ ppr (instToId m) -}]
+
+
+pprDFuns :: [DFunId] -> SDoc
+-- Prints the dfun as an instance declaration
+pprDFuns dfuns = vcat [ hang (ppr (getSrcLoc dfun) <> colon)
+ 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta,
+ pprClassPred clas tys])
+ | dfun <- dfuns
+ , let (_, theta, clas, tys) = tcSplitDFunTy (idType dfun) ]
+ -- Print without the for-all, which the programmer doesn't write
-tidyInst :: TidyEnv -> Inst -> (TidyEnv, Inst)
-tidyInst env (LitInst u lit ty orig loc)
- = (env', LitInst u lit ty' orig loc)
- where
- (env', ty') = tidyOpenType env ty
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
-tidyInst env (Dict u clas tys orig loc)
- = (env', Dict u clas tys' orig loc)
- where
- (env', tys') = tidyOpenTypes env tys
+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 orig loc)
- = (env', Method u id tys' theta tau orig 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
-
-tidyInsts env insts = mapAccumL tidyInst env insts
+ env' = tidyFreeTyVars env (tyVarsOfInsts insts)
-show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
+tidyInsts :: [Inst] -> (TidyEnv, [Inst])
+tidyInsts insts = tidyMoreInsts emptyTidyEnv insts
+
+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}
+ Extending the instance environment
%* *
%************************************************************************
\begin{code}
-type InstanceMapper = Class -> ClassInstEnv
+tcExtendLocalInstEnv :: [DFunId] -> TcM a -> TcM a
+ -- Add new locally-defined instances
+tcExtendLocalInstEnv dfuns thing_inside
+ = do { traceDFuns dfuns
+ ; env <- getGblEnv
+ ; dflags <- getDOpts
+ ; inst_env' <- foldlM (addInst dflags) (tcg_inst_env env) dfuns
+ ; let env' = env { tcg_insts = dfuns ++ tcg_insts env,
+ tcg_inst_env = inst_env' }
+ ; setGblEnv env' thing_inside }
+
+addInst :: DynFlags -> InstEnv -> DFunId -> TcM InstEnv
+-- Check that the proposed new instance is OK,
+-- and then add it to the home inst env
+addInst dflags home_ie dfun
+ = do { -- Load imported instances, so that we report
+ -- duplicates correctly
+ pkg_ie <- loadImportedInsts cls tys
+
+ -- Check functional dependencies
+ ; case checkFunDeps (pkg_ie, home_ie) dfun of
+ Just dfuns -> funDepErr dfun dfuns
+ Nothing -> return ()
+
+ -- Check for duplicate instance decls
+ ; let { (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys
+ ; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,
+ isJust (matchTys (mkVarSet tvs) tys dup_tys)] }
+ -- Find memebers of the match list which
+ -- dfun itself matches. If the match is 2-way, it's a duplicate
+ ; case dup_dfuns of
+ dup_dfun : _ -> dupInstErr dfun dup_dfun
+ [] -> return ()
+
+ -- OK, now extend the envt
+ ; return (extendInstEnv home_ie dfun) }
+ where
+ (tvs, _, cls, tys) = tcSplitDFunTy (idType dfun)
+
+traceDFuns dfuns
+ = traceTc (text "Adding instances:" <+> vcat (map pp dfuns))
+ where
+ pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
+
+funDepErr dfun dfuns
+ = addDictLoc dfun $
+ addErr (hang (ptext SLIT("Functional dependencies conflict between instance declarations:"))
+ 2 (pprDFuns (dfun:dfuns)))
+dupInstErr dfun dup_dfun
+ = addDictLoc dfun $
+ addErr (hang (ptext SLIT("Duplicate instance declarations:"))
+ 2 (pprDFuns [dfun, dup_dfun]))
+
+addDictLoc dfun thing_inside
+ = addSrcSpan (mkSrcSpan loc loc) thing_inside
+ where
+ loc = getSrcLoc dfun
\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.
+%************************************************************************
+%* *
+\subsection{Looking up Insts}
+%* *
+%************************************************************************
\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)
+ | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal
+ | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts
--- Dictionaries
+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
-lookupInst dict@(Dict _ clas tys orig loc)
- = case lookupSpecEnv (ppr clas) (classInstEnv clas) tys of
-
- Just (tenv, dfun_id)
- -> let
- (tyvars, rho) = splitForAllTys (idType dfun_id)
- ty_args = map (expectJust "Inst" . lookupVarEnv tenv) tyvars
- -- tenv should bind all the tyvars
- dfun_rho = substTopTy tenv rho
- (theta, tau) = splitRhoTy dfun_rho
- ty_app = mkHsTyApp (HsVar dfun_id) ty_args
- in
- if null theta then
- returnNF_Tc (SimpleInst ty_app)
- else
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- let
- rhs = mkHsDictApp ty_app dict_ids
- in
- returnNF_Tc (GenInst dicts rhs)
-
- Nothing -> returnNF_Tc NoInstance
-- Methods
-lookupInst inst@(Method _ id tys theta _ orig loc)
- = newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
+lookupInst inst@(Method _ id tys theta _ loc)
+ = newDictsAtLoc loc theta `thenM` \ dicts ->
+ returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (L span (HsVar id)) tys) (map instToId dicts)))
+ where
+ span = instLocSrcSpan loc
-- Literals
-lookupInst inst@(LitInst u (OverloadedIntegral i) ty orig 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
-
- | 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 orig 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 orig 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]
-
--- similar idea for overloaded floating point literals: if the literal is
--- *definitely* a float or a double, generate the real thing here.
+-- 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 ->
+ mkIntegerLit i `thenM` \ integer_lit ->
+ returnM (GenInst [method_inst]
+ (mkHsApp (L (instLocSrcSpan loc)
+ (HsVar (instToId method_inst))) integer_lit))
+
+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] (mkHsApp (L (instLocSrcSpan loc)
+ (HsVar (instToId method_inst))) rat_lit))
-lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
- | isFloatTy ty = returnNF_Tc (GenInst [] float_lit)
- | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit)
-
- | otherwise
- = tcLookupValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
-
- -- The type Rational isn't wired in so we have to conjure it up
- tcLookupTyConByKey rationalTyConKey `thenNF_Tc` \ rational_tycon ->
+-- Dictionaries
+lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
+ = do { dflags <- getDOpts
+ ; if all tcIsTyVarTy tys &&
+ not (dopt Opt_AllowUndecidableInstances dflags)
+ -- Common special case; no lookup
+ -- NB: tcIsTyVarTy... don't look through newtypes!
+ -- Don't take this short cut if we allow undecidable instances
+ -- because we might have "instance T a where ...".
+ -- [That means we need -fallow-undecidable-instances in the
+ -- client module, as well as the module with the instance decl.]
+ then return NoInstance
+
+ else do
+ { pkg_ie <- loadImportedInsts clas tys
+ -- Suck in any instance decls that may be relevant
+ ; tcg_env <- getGblEnv
+ ; case lookupInstEnv dflags (pkg_ie, tcg_inst_env tcg_env) clas tys of {
+ ([(tenv, (_,_,dfun_id))], []) -> instantiate_dfun tenv dfun_id pred loc ;
+ (matches, unifs) -> do
+ { traceTc (text "lookupInst" <+> vcat [text "matches" <+> ppr matches,
+ text "unifs" <+> ppr unifs])
+ ; return NoInstance } } } }
+ -- In the case of overlap (multiple matches) we report
+ -- NoInstance here. That has the effect of making the
+ -- context-simplifier return the dict as an irreducible one.
+ -- Then it'll be given to addNoInstanceErrs, which will do another
+ -- lookupInstEnv to get the detailed info about what went wrong.
+
+lookupInst (Dict _ _ _) = returnM NoInstance
+
+-----------------
+instantiate_dfun tenv dfun_id pred loc
+ = -- Record that this dfun is needed
+ record_dfun_usage dfun_id `thenM_`
+
+ -- 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_`
let
- rational_ty = mkSynTy rational_tycon []
- rational_lit = HsLitOut (HsFrac f) rational_ty
+ (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
- newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
-
+ mappM mk_ty_arg tyvars `thenM` \ ty_args ->
+ let
+ dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho
+ (theta, _) = tcSplitPhiTy dfun_rho
+ ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id)) ty_args
+ in
+ if null theta then
+ returnM (SimpleInst ty_app)
+ else
+ newDictsAtLoc loc theta `thenM` \ dicts ->
+ let
+ rhs = mkHsDictApp ty_app (map instToId dicts)
+ in
+ returnM (GenInst dicts rhs)
+
+record_dfun_usage dfun_id
+ | isInternalName dfun_name = return () -- From this module
+ | not (isHomePackageName dfun_name) = return () -- From another package package
+ | otherwise = getGblEnv `thenM` \ tcg_env ->
+ updMutVar (tcg_inst_uses tcg_env)
+ (`addOneToNameSet` idName dfun_id)
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]
+ dfun_name = idName dfun_id
-\end{code}
-
-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.
-
-\begin{code}
-lookupSimpleInst :: ClassInstEnv
- -> Class
- -> [Type] -- Look up (c,t)
- -> NF_TcM s (Maybe ThetaType) -- Here are the needed (c,t)s
-
-lookupSimpleInst class_inst_env clas tys
- = case lookupSpecEnv (ppr clas) class_inst_env tys of
- Nothing -> returnNF_Tc Nothing
-
- Just (tenv, dfun)
- -> returnNF_Tc (Just (substTopTheta tenv theta))
- where
- (_, theta, _) = splitSigmaTy (idType dfun)
+tcGetInstEnvs :: TcM (InstEnv, InstEnv)
+-- Gets both the home-pkg inst env (includes module being compiled)
+-- and the external-package inst-env
+tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv;
+ return (tcg_inst_env env, eps_inst_env eps) }
\end{code}
%************************************************************************
%* *
-\subsection[Inst-origin]{The @InstOrigin@ type}
+ Re-mappable syntax
%* *
%************************************************************************
-The @InstOrigin@ type gives information about where a dictionary came from.
-This is important for decent error message reporting because dictionaries
-don't appear in the original source code. Doubtless this type will evolve...
-
-\begin{code}
-data InstOrigin
- = OccurrenceOf TcId -- Occurrence of an overloaded identifier
- | OccurrenceOfCon Id -- Occurrence of a data constructor
-
- | RecordUpdOrigin
-
- | DataDeclOrigin -- Typechecking a data declaration
-
- | InstanceDeclOrigin -- Typechecking an instance decl
-
- | LiteralOrigin HsLit -- Occurrence of a literal
-
- | PatOrigin RenamedPat
- | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
+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:
- | SignatureOrigin -- A dict created from a type signature
- | Rank2Origin -- A dict created when typechecking the argument
- -- of a rank-2 typed function
+ (>>) :: HB m n mn => m a -> n b -> mn b
- | DoOrigin -- The monad for a do expression
+So the idea is to generate a local binding for (>>), thus:
- | ClassDeclOrigin -- Manufactured during a class decl
+ let then72 :: forall a b. m a -> m b -> m b
+ then72 = ...something involving the user's (>>)...
+ in
+ ...the do-expression...
- | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
- Type
+Now the do-expression can proceed using then72, which has exactly
+the expected type.
- -- When specialising instances the instance info attached to
- -- each class is not yet ready, so we record it inside the
- -- origin information. This is a bit of a hack, but it works
- -- fine. (Patrick is to blame [WDP].)
+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.
- | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
-
- -- Argument or result of a ccall
- -- Dictionaries with this origin aren't actually mentioned in the
- -- translated term, and so need not be bound. Nor should they
- -- be abstracted over.
+\begin{code}
+tcSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> (Name, LHsExpr Name) -- (Standard name, user name)
+ -> TcM (Name, LHsExpr TcId) -- (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, L span (HsVar user_nm))
+ | std_nm == user_nm
+ = addSrcSpan span (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) $
- | CCallOrigin String -- CCall label
- (Maybe RenamedHsExpr) -- Nothing if it's the result
- -- Just arg, for an argument
+ -- Check that the user-supplied thing has the
+ -- same type as the standard one
+ tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
+ returnM (std_nm, expr)
- | LitLitOrigin String -- the litlit
+tcStdSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> Name -- Standard name
+ -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression)
- | UnknownOrigin -- Help! I give up...
-\end{code}
+tcStdSyntaxName orig ty std_nm
+ = newMethodFromName orig ty std_nm `thenM` \ id ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (std_nm, L span (HsVar id))
-\begin{code}
-pprOrigin :: Inst -> SDoc
-pprOrigin inst
- = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
- where
- (orig, locn) = case inst of
- Dict _ _ _ orig loc -> (orig,loc)
- Method _ _ _ _ _ orig loc -> (orig,loc)
- LitInst _ _ _ orig loc -> (orig,loc)
-
- pp_orig (OccurrenceOf id)
- = hsep [ptext SLIT("use of"), quotes (ppr id)]
- pp_orig (OccurrenceOfCon id)
- = hsep [ptext SLIT("use of"), quotes (ppr id)]
- pp_orig (LiteralOrigin lit)
- = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
- pp_orig (PatOrigin pat)
- = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
- pp_orig (InstanceDeclOrigin)
- = ptext SLIT("an instance declaration")
- pp_orig (ArithSeqOrigin seq)
- = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
- pp_orig (SignatureOrigin)
- = ptext SLIT("a type signature")
- pp_orig (Rank2Origin)
- = ptext SLIT("a function with an overloaded argument type")
- pp_orig (DoOrigin)
- = ptext SLIT("a do statement")
- pp_orig (ClassDeclOrigin)
- = ptext SLIT("a class declaration")
- pp_orig (InstanceSpecOrigin clas ty)
- = hsep [text "a SPECIALIZE instance pragma; class",
- quotes (ppr clas), text "type:", ppr ty]
- pp_orig (ValSpecOrigin name)
- = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
- pp_orig (CCallOrigin clabel Nothing{-ccall result-})
- = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
- pp_orig (CCallOrigin clabel (Just arg_expr))
- = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
- text "namely", quotes (ppr arg_expr)]
- pp_orig (LitLitOrigin s)
- = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
- pp_orig (UnknownOrigin)
- = ptext SLIT("...oops -- I don't know where the overloading came from!")
+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