\section[Inst]{The @Inst@ type: dictionaries or method instances}
\begin{code}
-#include "HsVersions.h"
-
module Inst (
- Inst(..), -- Visible only to TcSimplify
+ LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs, mkLIE,
+ pprInsts, pprInstsInFull,
- InstOrigin(..), OverloadedLit(..),
- LIE(..), emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs,
+ Inst, OverloadedLit(..), pprInst,
- InstanceMapper(..),
+ InstanceMapper,
- newDicts, newDictsAtLoc, newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newDictFromOld, newDicts, newDictsAtLoc,
+ newMethod, newMethodWithGivenTy, newOverloadedLit,
- instType, tyVarsOfInst, lookupInst, lookupSimpleInst,
+ tyVarsOfInst, instLoc, getDictClassTys,
- isDict, isTyVarDict,
+ lookupInst, lookupSimpleInst, LookupInstResult(..),
+
+ isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor,
+ instBindingRequired, instCanBeGeneralised,
zonkInst, instToId,
- matchesInst,
- instBindingRequired, instCanBeGeneralised,
-
- pprInst
+ InstOrigin(..), pprOrigin
) where
-IMP_Ubiq()
-
-import HsSyn ( HsLit(..), HsExpr(..), HsBinds,
- InPat, OutPat, Stmt, Qualifier, Match,
- ArithSeqInfo, PolyType, Fake )
-import RnHsSyn ( RenamedArithSeqInfo(..), RenamedHsExpr(..) )
-import TcHsSyn ( TcIdOcc(..), TcExpr(..), TcIdBndr(..),
- mkHsTyApp, mkHsDictApp, tcIdTyVars )
+#include "HsVersions.h"
-import TcMonad hiding ( rnMtoTcM )
+import CmdLineOpts ( opt_AllowOverlappingInstances )
+import HsSyn ( HsLit(..), HsExpr(..), MonoBinds )
+import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr )
+import TcHsSyn ( TcExpr, TcIdOcc(..), TcIdBndr,
+ mkHsTyApp, mkHsDictApp, tcIdTyVars, zonkTcId
+ )
+import TcMonad
import TcEnv ( tcLookupGlobalValueByKey, tcLookupTyConByKey )
-import TcType ( TcType(..), TcRhoType(..), TcMaybe, TcTyVarSet(..),
- tcInstType, zonkTcType )
-
-import Bag ( emptyBag, unitBag, unionBags, unionManyBags, listToBag, consBag )
-import Class ( isCcallishClass, isNoDictClass, classInstEnv,
- Class(..), GenClass, ClassInstEnv(..)
+import TcType ( TcThetaType,
+ TcType, TcTauType, TcMaybe, TcTyVarSet,
+ tcInstType, zonkTcType, zonkTcTypes, tcSplitForAllTy,
+ zonkTcThetaType
)
-import ErrUtils ( addErrLoc, Error(..) )
-import Id ( GenId, idType, mkInstId )
-import MatchEnv ( lookupMEnv, insertMEnv )
-import Name ( mkLocalName, getLocalName, Name )
-import Outputable
-import PprType ( GenClass, TyCon, GenType, GenTyVar )
-import PprStyle ( PprStyle(..) )
-import Pretty
-import RnHsSyn ( RnName{-instance NamedThing-} )
-import SpecEnv ( SpecEnv(..) )
-import SrcLoc ( SrcLoc, mkUnknownSrcLoc )
-import Type ( GenType, eqSimpleTy, instantiateTy,
- isTyVarTy, mkDictTy, splitForAllTy, splitSigmaTy,
- splitRhoTy, matchTy, tyVarsOfType, tyVarsOfTypes,
+import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
+ listToBag, consBag, Bag )
+import Class ( classInstEnv,
+ Class, ClassInstEnv
+ )
+import MkId ( mkUserLocal, mkSysLocal )
+import Id ( Id, idType, mkId,
+ GenIdSet, elementOfIdSet
+ )
+import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
+import Name ( OccName(..), Name, occNameString, getOccName )
+import PprType ( TyCon, pprConstraint )
+import SpecEnv ( SpecEnv, lookupSpecEnv )
+import SrcLoc ( SrcLoc )
+import Type ( Type, ThetaType, instantiateTy, instantiateThetaTy,
+ isTyVarTy, mkDictTy, splitForAllTys, splitSigmaTy,
+ splitRhoTy, tyVarsOfType, tyVarsOfTypes,
mkSynTy
)
-import TyVar ( unionTyVarSets, GenTyVar )
+import TyVar ( zipTyVarEnv, lookupTyVarEnv, unionTyVarSets )
import TysPrim ( intPrimTy )
-import TysWiredIn ( intDataCon, integerTy )
-import Unique ( showUnique, fromRationalClassOpKey, rationalTyConKey,
+import TysWiredIn ( intDataCon, integerTy, isIntTy, isIntegerTy, inIntRange )
+import Unique ( fromRationalClassOpKey, rationalTyConKey,
fromIntClassOpKey, fromIntegerClassOpKey, Unique
)
-import Util ( panic, zipEqual, zipWithEqual, assoc, assertPanic, pprTrace{-ToDo:rm-} )
+import Maybes ( MaybeErr, expectJust )
+import Util ( thenCmp, zipWithEqual )
+import Outputable
\end{code}
%************************************************************************
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 s -> NF_TcM s (LIE s)
zonkLIE lie = mapBagNF_Tc zonkInst lie
+
+pprInsts :: [Inst s] -> 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}
%************************************************************************
data Inst s
= Dict
Unique
- Class -- The type of the dict is (c t), where
- (TcType s) -- c is the class and t the type;
+ Class -- The type of the dict is (c ts), where
+ [TcType s] -- c is the class and ts the types;
(InstOrigin s)
SrcLoc
-- should be instantiated.
-- These types must saturate the Id's foralls.
- (TcRhoType s) -- Cached: (type-of-id applied to inst_tys)
- -- If this type is (theta => tau) then the type of the Method
- -- is tau, and the method can be built by saying
- -- id inst_tys dicts
- -- where dicts are constructed from theta
+ (TcThetaType s) -- The (types of the) dictionaries to which the function
+ -- must be applied to get the method
+
+ (TcTauType s) -- The type of the method
(InstOrigin s)
SrcLoc
+ -- INVARIANT: in (Method u f tys theta tau loc)
+ -- type of (f tys dicts(from theta)) = tau
+
| LitInst
Unique
OverloadedLit
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 s) where
+ compare = cmpInst
+
+instance Eq (Inst s) 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}
+
+
+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
+
+getDictClassTys (Dict u clas tys _ _) = (clas, tys)
+
+tyVarsOfInst :: Inst s -> TcTyVarSet s
+tyVarsOfInst (Dict _ _ tys _ _) = tyVarsOfTypes tys
+tyVarsOfInst (Method _ id tys _ _ _ _) = tyVarsOfTypes tys `unionTyVarSets` tcIdTyVars id
+ -- The id might not be a RealId; in the case of
+ -- locally-overloaded class methods, for example
+tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
+\end{code}
+
+Predicates
+~~~~~~~~~~
+\begin{code}
+isDict :: Inst s -> Bool
+isDict (Dict _ _ _ _ _) = True
+isDict other = False
+
+isMethodFor :: GenIdSet (TcType s) -> Inst s -> Bool
+isMethodFor ids (Method uniq (TcId id) tys _ _ orig loc)
+ = id `elementOfIdSet` ids
+isMethodFor ids inst
+ = False
-getInstOrigin (Dict u clas ty origin loc) = origin
-getInstOrigin (Method u clas ty rho origin loc) = origin
-getInstOrigin (LitInst u lit ty origin loc) = origin
+isTyVarDict :: Inst s -> Bool
+isTyVarDict (Dict _ _ tys _ _) = all isTyVarTy tys
+isTyVarDict other = False
+
+isStdClassTyVarDict (Dict _ clas [ty] _ _) = isStandardClass clas && isTyVarTy ty
+isStdClassTyVarDict other = False
\end{code}
+Two predicates which deal with the case where class constraints don't
+necessarily result in bindings. The first tells whether an @Inst@
+must be witnessed by an actual binding; the second tells whether an
+@Inst@ can be generalised over.
+
+\begin{code}
+instBindingRequired :: Inst s -> Bool
+instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
+instBindingRequired other = True
+
+instCanBeGeneralised :: Inst s -> Bool
+instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
+\end{code}
+
+
Construction
~~~~~~~~~~~~
\begin{code}
newDicts :: InstOrigin s
- -> [(Class, TcType s)]
+ -> TcThetaType s
-> NF_TcM s (LIE s, [TcIdOcc s])
newDicts orig theta
= tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
- dicts = zipWithEqual "newDicts" mk_dict new_uniqs theta
- in
- returnNF_Tc (listToBag dicts, map instToId dicts)
+ newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, ids) ->
+ returnNF_Tc (listToBag dicts, ids)
+
+-- Local function, similar to newDicts,
+-- but with slightly different interface
+newDictsAtLoc :: InstOrigin s
+ -> SrcLoc
+ -> TcThetaType s
+ -> NF_TcM s ([Inst s], [TcIdOcc s])
+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 s -> Class -> [TcType s] -> NF_TcM s (Inst s)
+newDictFromOld (Dict _ _ _ orig loc) clas tys
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ returnNF_Tc (Dict uniq clas tys orig loc)
-newDictsAtLoc orig loc theta -- Local function, similar to newDicts,
- -- but with slightly different interface
- = tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
- dicts = zipWithEqual "newDictsAtLoc" mk_dict new_uniqs theta
- in
- returnNF_Tc (dicts, map instToId dicts)
newMethod :: InstOrigin s
-> TcIdOcc s
newMethod orig id tys
= -- Get the Id type and instantiate it at the specified types
(case id of
- RealId id -> let (tyvars, rho) = splitForAllTy (idType id)
+ RealId id -> let (tyvars, rho) = splitForAllTys (idType id)
in
- (if length tyvars /= length tys then pprTrace "newMethod" (ppr PprDebug (idType id)) else \x->x) $
- tcInstType (zip{-Equal "newMethod"-} tyvars tys) rho
- TcId id -> let (tyvars, rho) = splitForAllTy (idType id)
- in returnNF_Tc (instantiateTy (zipEqual "newMethod(2)" tyvars tys) rho)
+ ASSERT( length tyvars == length tys)
+ tcInstType (zipTyVarEnv tyvars tys) rho
+
+ TcId id -> tcSplitForAllTy (idType id) `thenNF_Tc` \ (tyvars, rho) ->
+ returnNF_Tc (instantiateTy (zipTyVarEnv tyvars tys) rho)
) `thenNF_Tc` \ rho_ty ->
+ let
+ (theta, tau) = splitRhoTy rho_ty
+ in
-- Our friend does the rest
- newMethodWithGivenTy orig id tys rho_ty
+ newMethodWithGivenTy orig id tys theta tau
-newMethodWithGivenTy orig id tys rho_ty
+newMethodWithGivenTy orig id tys theta tau
= tcGetSrcLoc `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq id tys rho_ty orig loc
+ meth_inst = Method new_uniq id tys theta tau orig loc
in
returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
-newMethodAtLoc :: InstOrigin s -> SrcLoc -> Id -> [TcType s] -> NF_TcM s (Inst s, TcIdOcc s)
+newMethodAtLoc :: InstOrigin s -> SrcLoc
+ -> Id -> [TcType s]
+ -> NF_TcM s (Inst s, TcIdOcc s)
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
let
- (tyvars,rho) = splitForAllTy (idType real_id)
+ (tyvars,rho) = splitForAllTys (idType real_id)
in
- tcInstType (zipEqual "newMethodAtLoc" tyvars tys) rho `thenNF_Tc` \ rho_ty ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ tcInstType (zipTyVarEnv tyvars tys) rho `thenNF_Tc` \ rho_ty ->
+ tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq (RealId real_id) tys rho_ty orig loc
+ (theta, tau) = splitRhoTy rho_ty
+ meth_inst = Method new_uniq (RealId real_id) tys theta tau orig loc
in
returnNF_Tc (meth_inst, instToId meth_inst)
newOverloadedLit :: InstOrigin s
-> OverloadedLit
-> TcType s
- -> NF_TcM s (LIE s, TcIdOcc s)
-newOverloadedLit orig lit ty
+ -> NF_TcM s (TcExpr s, LIE s)
+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 = HsApp (HsVar (RealId intDataCon)) intprim_lit
+
+newOverloadedLit orig lit ty -- The general case
= tcGetSrcLoc `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
let
lit_inst = LitInst new_uniq lit ty orig loc
in
- returnNF_Tc (unitLIE lit_inst, instToId lit_inst)
+ returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst)
\end{code}
\begin{code}
instToId :: Inst s -> TcIdOcc s
instToId (Dict u clas ty orig loc)
- = TcId (mkInstId u (mkDictTy clas ty) (mkLocalName u str False{-emph name-} loc))
- where
- str = SLIT("d.") _APPEND_ (getLocalName clas)
-instToId (Method u id tys rho_ty orig loc)
- = TcId (mkInstId u tau_ty (mkLocalName u str False{-emph name-} loc))
+ = TcId (mkUserLocal occ u (mkDictTy clas ty) loc)
where
- (_, tau_ty) = splitRhoTy rho_ty -- NB The method Id has just the tau type
- str = SLIT("m.") _APPEND_ (getLocalName id)
+ occ = VarOcc (SLIT("d.") _APPEND_ (occNameString (getOccName clas)))
+instToId (Method u id tys theta tau orig loc)
+ = TcId (mkUserLocal (getOccName id) u tau loc)
+
instToId (LitInst u list ty orig loc)
- = TcId (mkInstId u ty (mkLocalName u SLIT("lit") True{-emph uniq-} loc))
-\end{code}
-
-\begin{code}
-instType :: Inst s -> TcType s
-instType (Dict _ clas ty _ _) = mkDictTy clas ty
-instType (LitInst _ _ ty _ _) = ty
-instType (Method _ id tys ty _ _) = ty
+ = TcId (mkSysLocal SLIT("lit") u ty loc)
\end{code}
\begin{code}
zonkInst :: Inst s -> NF_TcM s (Inst s)
-zonkInst (Dict u clas ty orig loc)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (Dict u clas new_ty orig loc)
-
-zonkInst (Method u id tys rho orig loc) -- Doesn't zonk the id!
- = mapNF_Tc zonkTcType tys `thenNF_Tc` \ new_tys ->
- zonkTcType rho `thenNF_Tc` \ new_rho ->
- returnNF_Tc (Method u id new_tys new_rho orig loc)
+zonkInst (Dict u clas tys orig loc)
+ = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
+ returnNF_Tc (Dict u clas new_tys orig loc)
+
+zonkInst (Method u id tys theta tau orig loc)
+ = zonkTcId id `thenNF_Tc` \ new_id ->
+ -- Essential to zonk the id in case it's a local variable
+ 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)
zonkInst (LitInst u lit ty orig loc)
= zonkTcType ty `thenNF_Tc` \ new_ty ->
\end{code}
-\begin{code}
-tyVarsOfInst :: Inst s -> TcTyVarSet s
-tyVarsOfInst (Dict _ _ ty _ _) = tyVarsOfType ty
-tyVarsOfInst (Method _ id tys rho _ _) = tyVarsOfTypes tys `unionTyVarSets` tcIdTyVars id
- -- The id might not be a RealId; in the case of
- -- locally-overloaded class methods, for example
-tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
-\end{code}
-
-@matchesInst@ checks when two @Inst@s are instances of the same
-thing at the same type, even if their uniques differ.
-
-\begin{code}
-matchesInst :: Inst s -> Inst s -> Bool
-
-matchesInst (Dict _ clas1 ty1 _ _) (Dict _ clas2 ty2 _ _)
- = clas1 == clas2 && ty1 `eqSimpleTy` ty2
-
-matchesInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _)
- = id1 == id2
- && and (zipWith eqSimpleTy tys1 tys2)
- && length tys1 == length tys2
-
-matchesInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _)
- = lit1 `eq` lit2 && ty1 `eqSimpleTy` ty2
- where
- (OverloadedIntegral i1) `eq` (OverloadedIntegral i2) = i1 == i2
- (OverloadedFractional f1) `eq` (OverloadedFractional f2) = f1 == f2
- _ `eq` _ = False
-
-matchesInst other1 other2 = False
-\end{code}
-
-
-Predicates
-~~~~~~~~~~
-\begin{code}
-isDict :: Inst s -> Bool
-isDict (Dict _ _ _ _ _) = True
-isDict other = False
-
-isTyVarDict :: Inst s -> Bool
-isTyVarDict (Dict _ _ ty _ _) = isTyVarTy ty
-isTyVarDict other = False
-\end{code}
-
-Two predicates which deal with the case where class constraints don't
-necessarily result in bindings. The first tells whether an @Inst@
-must be witnessed by an actual binding; the second tells whether an
-@Inst@ can be generalised over.
-
-\begin{code}
-instBindingRequired :: Inst s -> Bool
-instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
-instBindingRequired other = True
-
-instCanBeGeneralised :: Inst s -> Bool
-instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
-\end{code}
-
-
Printing
~~~~~~~~
ToDo: improve these pretty-printing things. The ``origin'' is really only
\begin{code}
instance Outputable (Inst s) where
- ppr sty inst = ppr_inst sty ppNil (\ o l -> ppNil) inst
+ ppr inst = pprInst inst
-pprInst sty hdr inst = ppr_inst sty hdr (\ o l -> pprOrigin hdr o l sty) 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]
-ppr_inst sty hdr ppr_orig (LitInst u lit ty orig loc)
- = ppHang (ppr_orig orig loc)
- 4 (ppCat [case lit of
- OverloadedIntegral i -> ppInteger i
- OverloadedFractional f -> ppRational f,
- ppStr "at",
- ppr sty ty,
- show_uniq sty u])
+pprInst (Dict u clas tys orig loc) = pprConstraint clas tys <+> show_uniq u
-ppr_inst sty hdr ppr_orig (Dict u clas ty orig loc)
- = ppHang (ppr_orig orig loc)
- 4 (ppCat [ppr sty clas, ppr sty ty, show_uniq sty u])
+pprInst (Method u id tys _ _ orig loc)
+ = hsep [ppr id, ptext SLIT("at"),
+ interppSP tys,
+ show_uniq u]
-ppr_inst sty hdr ppr_orig (Method u id tys rho orig loc)
- = ppHang (ppr_orig orig loc)
- 4 (ppCat [ppr sty id, ppStr "at", interppSP sty tys, show_uniq sty u])
-
-show_uniq PprDebug u = ppr PprDebug u
-show_uniq sty u = ppNil
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
\end{code}
-Printing in error messages
-
-\begin{code}
-noInstanceErr inst sty = ppHang (ppPStr SLIT("No instance for:")) 4 (ppr sty inst)
-\end{code}
%************************************************************************
%* *
%************************************************************************
\begin{code}
-type InstanceMapper = Class -> (ClassInstEnv, ClassOp -> SpecEnv)
+type InstanceMapper = Class -> ClassInstEnv
\end{code}
A @ClassInstEnv@ lives inside a class, and identifies all the instances
the dfun type.
\begin{code}
+data LookupInstResult s
+ = NoInstance
+ | SimpleInst (TcExpr s) -- Just a variable, type application, or literal
+ | GenInst [Inst s] (TcExpr s) -- The expression and its needed insts
lookupInst :: Inst s
- -> TcM s ([Inst s],
- (TcIdOcc s, TcExpr s)) -- The new binding
+ -> NF_TcM s (LookupInstResult s)
-- Dictionaries
-lookupInst dict@(Dict _ clas ty orig loc)
- = case lookupMEnv matchTy (get_inst_env clas orig) ty of
- Nothing -> tcAddSrcLoc loc $
- tcAddErrCtxt (pprOrigin ""{-hdr-} orig loc) $
- failTc (noInstanceErr dict)
+lookupInst dict@(Dict _ clas tys orig loc)
+ = case lookupSpecEnv (classInstEnv clas) tys of
- Just (dfun_id, tenv)
+ Just (tenv, dfun_id)
-> let
- (tyvars, rho) = splitForAllTy (idType dfun_id)
- ty_args = map (assoc "lookupInst" tenv) tyvars
- -- tenv should bind all the tyvars
+ (tyvars, rho) = splitForAllTys (idType dfun_id)
+ ty_args = map (expectJust "Inst" . lookupTyVarEnv tenv) tyvars
+ -- tenv should bind all the tyvars
in
tcInstType tenv rho `thenNF_Tc` \ dfun_rho ->
let
(theta, tau) = splitRhoTy dfun_rho
+ ty_app = mkHsTyApp (HsVar (RealId 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 (mkHsTyApp (HsVar (RealId dfun_id)) ty_args) dict_ids
+ rhs = mkHsDictApp ty_app dict_ids
in
- returnTc (dicts, (instToId dict, rhs))
+ returnNF_Tc (GenInst dicts rhs)
+ Nothing -> returnNF_Tc NoInstance
-- Methods
-lookupInst inst@(Method _ id tys rho orig loc)
+lookupInst inst@(Method _ id tys theta _ orig loc)
= newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- returnTc (dicts, (instToId inst, mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
- where
- (theta,_) = splitRhoTy rho
+ returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
-- Literals
lookupInst inst@(LitInst u (OverloadedIntegral i) ty orig loc)
- | i >= toInteger minInt && i <= toInteger maxInt
- = -- It's overloaded but small enough to fit into an Int
- tcLookupGlobalValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int ->
- newMethodAtLoc orig loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) int_lit))
-
- | otherwise
- = -- Alas, it is overloaded and a big literal!
- tcLookupGlobalValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
+ | 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
+ = tcLookupGlobalValueByKey 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!
+ = tcLookupGlobalValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
newMethodAtLoc orig loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsInt i) integerTy)))
+ 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 = HsApp (HsVar (RealId intDataCon)) intprim_lit
lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
rational_lit = HsLitOut (HsFrac f) rational_ty
in
newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) rational_lit))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
\end{code}
There is a second, simpler interface, when you want an instance of a
\begin{code}
lookupSimpleInst :: ClassInstEnv
-> Class
- -> Type -- Look up (c,t)
- -> TcM s [(Class,Type)] -- Here are the needed (c,t)s
-
-lookupSimpleInst class_inst_env clas ty
- = case (lookupMEnv matchTy class_inst_env ty) of
- Nothing -> failTc (noSimpleInst clas ty)
- Just (dfun,tenv) -> returnTc [(c,instantiateTy tenv t) | (c,t) <- theta]
- where
- (_, theta, _) = splitSigmaTy (idType dfun)
-
-noSimpleInst clas ty sty
- = ppSep [ppStr "No instance for class", ppQuote (ppr sty clas),
- ppStr "at type", ppQuote (ppr sty ty)]
-\end{code}
-
-
-@mkInstSpecEnv@ is used to construct the @SpecEnv@ for a dfun.
-It does it by filtering the class's @InstEnv@. All pretty shady stuff.
-
-\begin{code}
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta = panic "mkInstSpecEnv"
-\end{code}
-
-\begin{pseudocode}
-mkInstSpecEnv :: Class -- class
- -> Type -- instance type
- -> [TyVarTemplate] -- instance tyvars
- -> ThetaType -- superclasses dicts
- -> SpecEnv -- specenv for dfun of instance
-
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta
- = mkSpecEnv (catMaybes (map maybe_spec_info matches))
- where
- matches = matchMEnv matchTy (classInstEnv clas) inst_ty
-
- maybe_spec_info (_, match_info, MkInstTemplate dfun _ [])
- = Just (SpecInfo (map (assocMaybe match_info) inst_tvs) (length inst_theta) dfun)
- maybe_spec_info (_, match_info, _)
- = Nothing
-\end{pseudocode}
+ -> [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 class_inst_env tys of
+ Nothing -> returnNF_Tc Nothing
-\begin{code}
-addClassInst
- :: ClassInstEnv -- Incoming envt
- -> Type -- The instance type: inst_ty
- -> Id -- Dict fun id to apply. Free tyvars of inst_ty must
- -- be the same as the forall'd tyvars of the dfun id.
- -> MaybeErr
- ClassInstEnv -- Success
- (Type, Id) -- Offending overlap
-
-addClassInst inst_env inst_ty dfun_id = insertMEnv matchTy inst_env inst_ty dfun_id
+ Just (tenv, dfun)
+ -> returnNF_Tc (Just (instantiateThetaTy tenv theta))
+ where
+ (_, theta, _) = splitSigmaTy (idType dfun)
\end{code}
| ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
| SignatureOrigin -- A dict created from a type signature
+ | Rank2Origin -- A dict created when typechecking the argument
+ -- of a rank-2 typed function
| DoOrigin -- The monad for a do expression
| ClassDeclOrigin -- Manufactured during a class decl
--- NO MORE!
--- | DerivingOrigin InstanceMapper
--- Class
--- TyCon
-
- -- During "deriving" operations we have an ever changing
- -- mapping of classes to instances, so we record it inside the
- -- origin information. This is a bit of a hack, but it works
- -- fine. (Simon is to blame [WDP].)
-
- | InstanceSpecOrigin InstanceMapper
- Class -- in a SPECIALIZE instance pragma
+ | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
Type
-- When specialising instances the instance info attached to
-- origin information. This is a bit of a hack, but it works
-- fine. (Patrick is to blame [WDP].)
--- | DefaultDeclOrigin -- Related to a `default' declaration
-
| ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
-- Argument or result of a ccall
\end{code}
\begin{code}
--- During deriving and instance specialisation operations
--- we can't get the instances of the class from inside the
--- class, because the latter ain't ready yet. Instead we
--- find a mapping from classes to envts inside the dict origin.
-
-get_inst_env :: Class -> InstOrigin s -> ClassInstEnv
--- get_inst_env clas (DerivingOrigin inst_mapper _ _)
--- = fst (inst_mapper clas)
-get_inst_env clas (InstanceSpecOrigin inst_mapper _ _)
- = fst (inst_mapper clas)
-get_inst_env clas other_orig = classInstEnv clas
-
-
-pprOrigin :: String -> InstOrigin s -> SrcLoc -> Error
-
-pprOrigin hdr orig locn
- = addErrLoc locn hdr $ \ sty ->
- case orig of
- OccurrenceOf id ->
- ppBesides [ppPStr SLIT("at a use of an overloaded identifier: `"),
- ppr sty id, ppChar '\'']
- OccurrenceOfCon id ->
- ppBesides [ppPStr SLIT("at a use of an overloaded constructor: `"),
- ppr sty id, ppChar '\'']
- InstanceDeclOrigin ->
- ppStr "in an instance declaration"
- LiteralOrigin lit ->
- ppCat [ppStr "at an overloaded literal:", ppr sty lit]
- ArithSeqOrigin seq ->
- ppCat [ppStr "at an arithmetic sequence:", ppr sty seq]
- SignatureOrigin ->
- ppStr "in a type signature"
- DoOrigin ->
- ppStr "in a do statement"
- ClassDeclOrigin ->
- ppStr "in a class declaration"
- InstanceSpecOrigin _ clas ty ->
- ppBesides [ppStr "in a SPECIALIZE instance pragma; class \"",
- ppr sty clas, ppStr "\" type: ", ppr sty ty]
- ValSpecOrigin name ->
- ppBesides [ppStr "in a SPECIALIZE user-pragma for `",
- ppr sty name, ppStr "'"]
- CCallOrigin clabel Nothing{-ccall result-} ->
- ppBesides [ppStr "in the result of the _ccall_ to `",
- ppStr clabel, ppStr "'"]
- CCallOrigin clabel (Just arg_expr) ->
- ppBesides [ppStr "in an argument in the _ccall_ to `",
- ppStr clabel, ppStr "', namely: ", ppr sty arg_expr]
- LitLitOrigin s ->
- ppBesides [ppStr "in this ``literal-literal'': ", ppStr s]
- UnknownOrigin ->
- ppStr "in... oops -- I don't know where the overloading came from!"
+pprOrigin :: Inst s -> 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 (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!")
\end{code}
projects / ghc-hetmet.git / blobdiff