Inst,
pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts,
- newDictsFromOld, newDicts,
- newMethod, newMethodWithGivenTy, newOverloadedLit,
- newIPDict, tcInstId,
+ newDictsFromOld, newDicts, cloneDict,
+ newMethod, newMethodFromName, newMethodWithGivenTy, newMethodAtLoc,
+ newOverloadedLit, newIPDict,
+ tcInstCall, tcInstDataCon, tcSyntaxName,
tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
ipNamesOfInst, ipNamesOfInsts, predsOfInst, predsOfInsts,
- instLoc, getDictClassTys,
+ instLoc, getDictClassTys, dictPred,
lookupInst, lookupSimpleInst, LookupInstResult(..),
isDict, isClassDict, isMethod,
+ isLinearInst, linearInstType,
isTyVarDict, isStdClassTyVarDict, isMethodFor,
instBindingRequired, instCanBeGeneralised,
#include "HsVersions.h"
-import CmdLineOpts ( opt_NoMethodSharing )
+import {-# SOURCE #-} TcExpr( tcExpr )
+
import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) )
-import TcHsSyn ( TcExpr, TcId,
+import TcHsSyn ( TcExpr, TcId, TypecheckedHsExpr,
mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId
)
import TcMonad
-import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupId )
+import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupId, tcLookupGlobalId, tcLookupTyCon )
import InstEnv ( InstLookupResult(..), lookupInstEnv )
-import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
- zonkTcThetaType, tcInstTyVar, tcInstType,
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType,
+ zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
-import TcType ( Type,
- SourceType(..), PredType, ThetaType,
- tcSplitForAllTys, tcSplitForAllTys,
- tcSplitMethodTy, tcSplitRhoTy, tcFunArgTy,
+import TcType ( Type, TcType, TcThetaType, TcPredType, TcTauType, TcTyVarSet,
+ SourceType(..), PredType, ThetaType, TyVarDetails(VanillaTv),
+ tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
+ tcSplitMethodTy, tcSplitPhiTy, mkGenTyConApp,
isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
- isClassPred, isTyVarClassPred,
+ isClassPred, isTyVarClassPred, isLinearPred,
getClassPredTys, getClassPredTys_maybe, mkPredName,
- tidyType, tidyTypes, tidyFreeTyVars,
- tcCmpType, tcCmpTypes, tcCmpPred
+ tidyType, tidyTypes, tidyFreeTyVars,
+ tcCmpType, tcCmpTypes, tcCmpPred, tcSplitSigmaTy
)
import CoreFVs ( idFreeTyVars )
import Class ( Class )
-import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId )
+import DataCon ( dataConSig )
+import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique )
import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
import Name ( Name, mkMethodOcc, getOccName )
-import NameSet ( NameSet )
-import PprType ( pprPred )
+import PprType ( pprPred, pprParendType )
import Subst ( emptyInScopeSet, mkSubst,
substTy, substTyWith, substTheta, mkTyVarSubst, mkTopTyVarSubst
)
import VarEnv ( TidyEnv, lookupSubstEnv, SubstResult(..) )
import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
import TysWiredIn ( floatDataCon, doubleDataCon )
-import PrelNames( fromIntegerName, fromRationalName )
+import PrelNames( fromIntegerName, fromRationalName, rationalTyConName )
import Util ( thenCmp, equalLength )
+import BasicTypes( IPName(..), mapIPName, ipNameName )
+
import Bag
import Outputable
\end{code}
| LitInst
Id
HsOverLit -- The literal from the occurrence site
+ -- INVARIANT: never a rebindable-syntax literal
+ -- Reason: tcSyntaxName does unification, and we
+ -- don't want to deal with that during tcSimplify
TcType -- The type at which the literal is used
InstLoc
\end{code}
instLoc (Method _ _ _ _ _ loc) = loc
instLoc (LitInst _ _ _ loc) = loc
+dictPred (Dict _ pred _ ) = pred
+dictPred inst = pprPanic "dictPred" (ppr inst)
+
getDictClassTys (Dict _ pred _) = getClassPredTys pred
predsOfInsts :: [Inst] -> [PredType]
ipNamesOfInsts :: [Inst] -> [Name]
ipNamesOfInst :: Inst -> [Name]
-- Get the implicit parameters mentioned by these Insts
+-- NB: ?x and %x get different Names
ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst]
-ipNamesOfInst (Dict _ (IParam n _) _) = [n]
-ipNamesOfInst (Method _ _ _ theta _ _) = [n | IParam n _ <- theta]
+ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n]
+ipNamesOfInst (Method _ _ _ theta _ _) = [ipNameName n | IParam n _ <- theta]
ipNamesOfInst other = []
tyVarsOfInst :: Inst -> TcTyVarSet
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
\begin{code}
instBindingRequired :: Inst -> Bool
instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas)
-instBindingRequired (Dict _ (IParam _ _) _) = False
instBindingRequired other = True
instCanBeGeneralised :: Inst -> Bool
= tcGetInstLoc orig `thenNF_Tc` \ loc ->
newDictsAtLoc loc theta
+cloneDict :: Inst -> NF_TcM Inst
+cloneDict (Dict id ty loc) = tcGetUnique `thenNF_Tc` \ uniq ->
+ returnNF_Tc (Dict (setIdUnique id uniq) ty loc)
+
newDictsFromOld :: Inst -> TcThetaType -> NF_TcM [Inst]
newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta
where
mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) pred inst_loc
--- For implicit parameters, since there is only one in scope
--- at any time, we use the name of the implicit parameter itself
-newIPDict orig name ty
- = tcGetInstLoc orig `thenNF_Tc` \ inst_loc ->
- returnNF_Tc (Dict (mkLocalId name (mkPredTy pred)) pred inst_loc)
- where pred = IParam name ty
+-- 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
+ -> NF_TcM (IPName Id, Inst)
+newIPDict orig ip_name ty
+ = tcGetInstLoc orig `thenNF_Tc` \ inst_loc@(_,loc,_) ->
+ tcGetUnique `thenNF_Tc` \ uniq ->
+ let
+ pred = IParam ip_name ty
+ id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)
+ in
+ returnNF_Tc (mapIPName (\n -> id) ip_name, Dict id pred inst_loc)
\end{code}
%* *
%************************************************************************
-tcInstId instantiates an occurrence of an Id.
-The instantiate_it loop runs round instantiating the Id.
-It has to be a loop because we are now prepared to entertain
-types like
- f:: forall a. Eq a => forall b. Baz b => tau
-We want to instantiate this to
- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
-
-The -fno-method-sharing flag controls what happens so far as the LIE
-is concerned. The default case is that for an overloaded function we
-generate a "method" Id, and add the Method Inst to the LIE. So you get
-something like
- f :: Num a => a -> a
- f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x
-If you specify -fno-method-sharing, the dictionary application
-isn't shared, so we get
- f :: Num a => a -> a
- f = /\a (d:Num a) (x:a) -> (+) a d x x
-This gets a bit less sharing, but
- a) it's better for RULEs involving overloaded functions
- b) perhaps fewer separated lambdas
-
\begin{code}
-tcInstId :: Id -> NF_TcM (TcExpr, LIE, TcType)
-tcInstId fun
- | opt_NoMethodSharing = loop_noshare (HsVar fun) (idType fun)
- | otherwise = loop_share fun
- where
- orig = OccurrenceOf fun
- loop_noshare fun fun_ty
- = tcInstType fun_ty `thenNF_Tc` \ (tyvars, theta, tau) ->
- let
- ty_app = mkHsTyApp fun (mkTyVarTys tyvars)
- in
- if null theta then -- Is it overloaded?
- returnNF_Tc (ty_app, emptyLIE, tau)
- else
- newDicts orig theta `thenNF_Tc` \ dicts ->
- loop_noshare (mkHsDictApp ty_app (map instToId dicts)) tau `thenNF_Tc` \ (expr, lie, final_tau) ->
- returnNF_Tc (expr, mkLIE dicts `plusLIE` lie, final_tau)
-
- loop_share fun
- = tcInstType (idType fun) `thenNF_Tc` \ (tyvars, theta, tau) ->
- let
- arg_tys = mkTyVarTys tyvars
- in
- if null theta then -- Is it overloaded?
- returnNF_Tc (mkHsTyApp (HsVar fun) arg_tys, emptyLIE, tau)
- else
- -- Yes, it's overloaded
- newMethodWithGivenTy orig fun arg_tys theta tau `thenNF_Tc` \ meth ->
- loop_share (instToId meth) `thenNF_Tc` \ (expr, lie, final_tau) ->
- returnNF_Tc (expr, unitLIE meth `plusLIE` lie, final_tau)
+tcInstCall :: InstOrigin -> TcType -> NF_TcM (TypecheckedHsExpr -> TypecheckedHsExpr, LIE, TcType)
+tcInstCall orig fun_ty -- fun_ty is usually a sigma-type
+ = tcInstType VanillaTv fun_ty `thenNF_Tc` \ (tyvars, theta, tau) ->
+ newDicts orig theta `thenNF_Tc` \ dicts ->
+ let
+ inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts)
+ in
+ returnNF_Tc (inst_fn, mkLIE dicts, tau)
+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) `thenNF_Tc` \ (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' `thenNF_Tc` \ stupid_dicts ->
+ newDicts orig ex_theta' `thenNF_Tc` \ ex_dicts ->
+
+ -- Note that we return the stupid theta *only* in the LIE;
+ -- we don't otherwise use it at all
+ returnNF_Tc (ty_args', map instToId ex_dicts, arg_tys', result_ty,
+ mkLIE stupid_dicts, mkLIE ex_dicts, ex_tvs')
+
+
+newMethodFromName :: InstOrigin -> TcType -> Name -> NF_TcM Inst
+newMethodFromName origin ty name
+ = tcLookupId name `thenNF_Tc` \ 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.
+ newMethod origin id [ty]
newMethod :: InstOrigin
-> TcId
(tyvars,rho) = tcSplitForAllTys (idType real_id)
rho_ty = ASSERT( equalLength tyvars tys )
substTy (mkTopTyVarSubst tyvars tys) rho
- (theta, tau) = tcSplitRhoTy rho_ty
+ (theta, tau) = tcSplitPhiTy rho_ty
in
newMethodWith inst_loc real_id tys theta tau `thenNF_Tc` \ meth_inst ->
returnNF_Tc (meth_inst, instToId meth_inst)
-> HsOverLit
-> TcType
-> NF_TcM (TcExpr, LIE)
-newOverloadedLit orig lit ty
- | Just expr <- shortCutLit lit ty
+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 fi `thenTc` \ (expr, lie, _) ->
+ returnTc (HsApp expr (HsLit (HsInteger i)), lie)
+
+ | Just expr <- shortCutIntLit i expected_ty
+ = returnNF_Tc (expr, emptyLIE)
+
+ | 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 fr `thenTc` \ (expr, lie, _) ->
+ mkRatLit r `thenNF_Tc` \ rat_lit ->
+ returnTc (HsApp expr rat_lit, lie)
+
+ | Just expr <- shortCutFracLit r expected_ty
= returnNF_Tc (expr, emptyLIE)
| otherwise
+ = newLitInst orig lit expected_ty
+
+newLitInst orig lit expected_ty
= tcGetInstLoc orig `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
+ zapToType expected_ty `thenNF_Tc_`
+ -- The expected type might be a 'hole' type variable,
+ -- in which case we must zap it to an ordinary type variable
let
- lit_inst = LitInst lit_id lit ty loc
- lit_id = mkSysLocal SLIT("lit") new_uniq ty
+ 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)
-shortCutLit :: HsOverLit -> TcType -> Maybe TcExpr
-shortCutLit (HsIntegral i fi) ty
- | isIntTy ty && inIntRange i && fi == fromIntegerName -- Short cut for Int
+shortCutIntLit :: Integer -> TcType -> Maybe TcExpr
+shortCutIntLit i ty
+ | isIntTy ty && inIntRange i -- Short cut for Int
= Just (HsLit (HsInt i))
- | isIntegerTy ty && fi == fromIntegerName -- Short cut for Integer
+ | isIntegerTy ty -- Short cut for Integer
= Just (HsLit (HsInteger i))
+ | otherwise = Nothing
-shortCutLit (HsFractional f fr) ty
- | isFloatTy ty && fr == fromRationalName
+shortCutFracLit :: Rational -> TcType -> Maybe TcExpr
+shortCutFracLit f ty
+ | isFloatTy ty
= Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)])
- | isDoubleTy ty && fr == fromRationalName
+ | isDoubleTy ty
= Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)])
+ | otherwise = Nothing
-shortCutLit lit ty
- = Nothing
+mkRatLit :: Rational -> NF_TcM TcExpr
+mkRatLit r
+ = tcLookupTyCon rationalTyConName `thenNF_Tc` \ rat_tc ->
+ let
+ rational_ty = mkGenTyConApp rat_tc []
+ in
+ returnNF_Tc (HsLit (HsRat r rational_ty))
\end{code}
pprInst m@(Method u id tys theta tau loc)
= hsep [ppr id, ptext SLIT("at"),
- brackets (interppSP tys) {- ,
+ brackets (sep (map pprParendType tys)) {- ,
ptext SLIT("theta"), ppr theta,
ptext SLIT("tau"), ppr tau
show_uniq u,
-- Dictionaries
lookupInst dict@(Dict _ (ClassP clas tys) loc)
- = tcGetInstEnv `thenNF_Tc` \ inst_env ->
- case lookupInstEnv inst_env clas tys of
+ = getDOptsTc `thenNF_Tc` \ dflags ->
+ tcGetInstEnv `thenNF_Tc` \ inst_env ->
+ case lookupInstEnv dflags inst_env clas tys of
FoundInst tenv dfun_id
- -> let
+ -> -- 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.
+ let
(tyvars, rho) = tcSplitForAllTys (idType dfun_id)
mk_ty_arg tv = case lookupSubstEnv tenv tv of
Just (DoneTy ty) -> returnNF_Tc ty
- Nothing -> tcInstTyVar tv `thenNF_Tc` \ tc_tv ->
+ Nothing -> tcInstTyVar VanillaTv tv `thenNF_Tc` \ tc_tv ->
returnTc (mkTyVarTy tc_tv)
in
mapNF_Tc mk_ty_arg tyvars `thenNF_Tc` \ ty_args ->
let
- subst = mkTyVarSubst tyvars ty_args
- dfun_rho = substTy subst rho
- (theta, _) = tcSplitRhoTy dfun_rho
- ty_app = mkHsTyApp (HsVar dfun_id) ty_args
+ 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)
-- [Same shortcut as in newOverloadedLit, but we
-- may have done some unification by now]
-lookupInst inst@(LitInst u lit ty loc)
- | Just expr <- shortCutLit lit ty
+lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc)
+ | Just expr <- shortCutIntLit i ty
= returnNF_Tc (GenInst [] expr) -- GenInst, not SimpleInst, because
-- expr may be a constructor application
-
-lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc)
- = tcLookupId from_integer_name `thenNF_Tc` \ from_integer ->
+ | otherwise
+ = ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant
+ tcLookupGlobalId fromIntegerName `thenNF_Tc` \ from_integer ->
newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnNF_Tc (GenInst [method_inst]
+ returnNF_Tc (GenInst [method_inst]
(HsApp (HsVar method_id) (HsLit (HsInteger i))))
lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc)
- = tcLookupId from_rat_name `thenNF_Tc` \ from_rational ->
+ | Just expr <- shortCutFracLit f ty
+ = returnNF_Tc (GenInst [] expr)
+
+ | otherwise
+ = ASSERT( from_rat_name == fromRationalName ) -- A LitInst invariant
+ tcLookupGlobalId fromRationalName `thenNF_Tc` \ from_rational ->
newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- let
- rational_ty = tcFunArgTy (idType method_id)
- rational_lit = HsLit (HsRat f rational_ty)
- in
- returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
+ mkRatLit f `thenNF_Tc` \ rat_lit ->
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rat_lit))
\end{code}
There is a second, simpler interface, when you want an instance of a
-> NF_TcM (Maybe ThetaType) -- Here are the needed (c,t)s
lookupSimpleInst clas tys
- = tcGetInstEnv `thenNF_Tc` \ inst_env ->
- case lookupInstEnv inst_env clas tys of
+ = getDOptsTc `thenNF_Tc` \ dflags ->
+ tcGetInstEnv `thenNF_Tc` \ inst_env ->
+ case lookupInstEnv dflags inst_env clas tys of
FoundInst tenv dfun
-> returnNF_Tc (Just (substTheta (mkSubst emptyInScopeSet tenv) theta))
where
(_, rho) = tcSplitForAllTys (idType dfun)
- (theta,_) = tcSplitRhoTy rho
+ (theta,_) = tcSplitPhiTy rho
other -> returnNF_Tc Nothing
\end{code}
+
+
+%************************************************************************
+%* *
+ Re-mappable syntax
+%* *
+%************************************************************************
+
+
+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:
+
+ (>>) :: HB m n mn => m a -> n b -> mn b
+
+So the idea is to generate a local binding for (>>), thus:
+
+ let then72 :: forall a b. m a -> m b -> m b
+ then72 = ...something involving the user's (>>)...
+ in
+ ...the do-expression...
+
+Now the do-expression can proceed using then72, which has exactly
+the expected type.
+
+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.
+
+\begin{code}
+tcSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> Name -> Name -- (Standard name, user name)
+ -> TcM (TcExpr, LIE, TcType) -- Suitable expression with its type
+
+-- 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 user_nm
+ | std_nm == user_nm
+ = newMethodFromName orig ty std_nm `thenNF_Tc` \ inst ->
+ let
+ id = instToId inst
+ in
+ returnTc (HsVar id, unitLIE inst, idType id)
+
+ | otherwise
+ = tcLookupGlobalId std_nm `thenNF_Tc` \ std_id ->
+ let
+ -- C.f. newMethodAtLoc
+ ([tv], _, tau) = tcSplitSigmaTy (idType std_id)
+ tau1 = substTy (mkTopTyVarSubst [tv] [ty]) tau
+ in
+ tcAddErrCtxtM (syntaxNameCtxt user_nm orig tau1) $
+ tcExpr (HsVar user_nm) tau1 `thenTc` \ (user_fn, lie) ->
+ returnTc (user_fn, lie, tau1)
+
+syntaxNameCtxt name orig ty tidy_env
+ = tcGetInstLoc orig `thenNF_Tc` \ 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
+ returnNF_Tc (tidy_env, msg)
+\end{code}
projects / ghc-hetmet.git / blobdiff