#include "HsVersions.h"
import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
- HsMatchContext(..), HsDoContext(..), mkMonoBind
+ HsMatchContext(..), HsDoContext(..),
+ mkMonoBind
)
import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy )
+import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy, mkHsDictApp, mkHsTyApp )
import TcMonad
-import TcUnify ( tcSub, tcGen, (<$>),
+import TcUnify ( tcSubExp, tcGen, (<$>),
unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy,
unifyTupleTy )
import BasicTypes ( RecFlag(..), isMarkedStrict )
import Inst ( InstOrigin(..),
LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs,
newOverloadedLit, newMethod, newIPDict,
- newDicts,
- instToId, tcInstId
+ newDicts, newMethodWithGivenTy,
+ instToId, tcInstCall, tcInstDataCon
)
import TcBinds ( tcBindsAndThen )
import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe,
import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
import TcPat ( badFieldCon )
import TcSimplify ( tcSimplifyIPs )
-import TcMType ( tcInstTyVars, newTyVarTy, newTyVarTys, zonkTcType )
-import TcType ( TcType, TcSigmaType, TcPhiType,
- tcSplitFunTys, tcSplitTyConApp,
- isSigmaTy, mkFunTy, mkAppTy, mkTyConTy,
+import TcMType ( tcInstTyVars, tcInstType, newHoleTyVarTy, zapToType,
+ newTyVarTy, newTyVarTys, zonkTcType, readHoleResult )
+import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
+ tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
+ isSigmaTy, mkFunTy, mkAppTy, mkTyConTy, mkFunTys,
mkTyConApp, mkClassPred, tcFunArgTy,
- tyVarsOfTypes,
+ tyVarsOfTypes, isLinearPred,
liftedTypeKind, openTypeKind, mkArrowKind,
tcSplitSigmaTy, tcTyConAppTyCon,
tidyOpenType
)
import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector, isDataConWrapId_maybe )
import DataCon ( dataConFieldLabels, dataConSig,
dataConStrictMarks
)
import Name ( Name )
-import TyCon ( TyCon, tyConTyVars, isAlgTyCon, tyConDataCons )
+import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
import Subst ( mkTopTyVarSubst, substTheta, substTy )
-import VarSet ( elemVarSet )
+import VarSet ( emptyVarSet, elemVarSet )
import TysWiredIn ( boolTy, mkListTy, mkPArrTy, listTyCon, parrTyCon )
import PrelNames ( cCallableClassName,
cReturnableClassName,
-> TcM (TcExpr, LIE) -- Generalised expr with expected type, and LIE
tcExpr expr expected_ty
+ = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenNF_Tc_`
+ tc_expr' expr expected_ty
+
+tc_expr' expr expected_ty
| not (isSigmaTy expected_ty) -- Monomorphic case
= tcMonoExpr expr expected_ty
| otherwise
- = tcGen expected_ty (tcMonoExpr expr) `thenTc` \ (gen_fn, expr', lie) ->
+ = tcGen expected_ty emptyVarSet (
+ tcMonoExpr expr
+ ) `thenTc` \ (gen_fn, expr', lie) ->
returnTc (gen_fn <$> expr', lie)
\end{code}
\begin{code}
tcMonoExpr :: RenamedHsExpr -- Expession to type check
- -> TcPhiType -- Expected type (could be a type variable)
+ -> TcRhoType -- Expected type (could be a type variable)
-- Definitely no foralls at the top
-- Can be a 'hole'.
-> TcM (TcExpr, LIE)
tcMonoExpr (HsVar name) res_ty
= tcId name `thenNF_Tc` \ (expr', lie1, id_ty) ->
- tcSub res_ty id_ty `thenTc` \ (co_fn, lie2) ->
+ tcSubExp res_ty id_ty `thenTc` \ (co_fn, lie2) ->
returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
tcMonoExpr (HsIPVar ip) res_ty
-- be a tau-type.)
newTyVarTy openTypeKind `thenNF_Tc` \ ip_ty ->
newIPDict (IPOcc ip) ip ip_ty `thenNF_Tc` \ (ip', inst) ->
- tcSub res_ty ip_ty `thenTc` \ (co_fn, lie) ->
+ tcSubExp res_ty ip_ty `thenTc` \ (co_fn, lie) ->
returnNF_Tc (co_fn <$> HsIPVar ip', lie `plusLIE` unitLIE inst)
\end{code}
\begin{code}
tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
= tcHsSigType ExprSigCtxt poly_ty `thenTc` \ sig_tc_ty ->
- tcAddErrCtxt (exprSigCtxt in_expr) $
tcExpr expr sig_tc_ty `thenTc` \ (expr', lie1) ->
- tcSub res_ty sig_tc_ty `thenTc` \ (co_fn, lie2) ->
- returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
+
+ -- Must instantiate the outer for-alls of sig_tc_ty
+ -- else we risk instantiating a ? res_ty to a forall-type
+ -- which breaks the invariant that tcMonoExpr only returns phi-types
+ tcAddErrCtxt (exprSigCtxt in_expr) $
+ tcInstCall SignatureOrigin sig_tc_ty `thenNF_Tc` \ (inst_fn, lie2, inst_sig_ty) ->
+ tcSubExp res_ty inst_sig_ty `thenTc` \ (co_fn, lie3) ->
+
+ returnTc (co_fn <$> inst_fn expr', lie1 `plusLIE` lie2 `plusLIE` lie3)
\end{code}
split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2) ->
tcAddErrCtxt (exprCtxt in_expr) $
- tcSub res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
returnTc (co_fn <$> SectionL arg1' op', lie1 `plusLIE` lie2 `plusLIE` lie3)
-- Right sections, equivalent to \ x -> x op expr, or
split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2) ->
tcAddErrCtxt (exprCtxt in_expr) $
- tcSub res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
returnTc (co_fn <$> SectionR op' arg2', lie1 `plusLIE` lie2 `plusLIE` lie3)
-- equivalent to (op e1) e2:
tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2a) ->
tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2b) ->
tcAddErrCtxt (exprCtxt in_expr) $
- tcSub res_ty op_res_ty `thenTc` \ (co_fn, lie3) ->
+ tcSubExp res_ty op_res_ty `thenTc` \ (co_fn, lie3) ->
returnTc (OpApp arg1' op' fix arg2',
lie1 `plusLIE` lie2a `plusLIE` lie2b `plusLIE` lie3)
\end{code}
tcAddErrCtxt (predCtxt pred) (
tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
- tcMonoExpr b1 res_ty `thenTc` \ (b1',lie2) ->
- tcMonoExpr b2 res_ty `thenTc` \ (b2',lie3) ->
+ zapToType res_ty `thenTc` \ res_ty' ->
+ -- C.f. the call to zapToType in TcMatches.tcMatches
+
+ tcMonoExpr b1 res_ty' `thenTc` \ (b1',lie2) ->
+ tcMonoExpr b2 res_ty' `thenTc` \ (b2',lie3) ->
returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3))
\end{code}
-- Figure out the tycon and data cons from the first field name
let
-- It's OK to use the non-tc splitters here (for a selector)
- (Just (AnId sel_id) : _) = maybe_sel_ids
- (_, _, tau) = tcSplitSigmaTy (idType sel_id) -- Selectors can be overloaded
- -- when the data type has a context
- data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector
- tycon = tcTyConAppTyCon data_ty
- data_cons = tyConDataCons tycon
- (con_tyvars, _, _, _, _, _) = dataConSig (head data_cons)
+ (Just (AnId sel_id) : _) = maybe_sel_ids
+
+ (_, _, tau) = tcSplitSigmaTy (idType sel_id) -- Selectors can be overloaded
+ -- when the data type has a context
+ data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector
+ tycon = tcTyConAppTyCon data_ty
+ data_cons = tyConDataCons tycon
+ tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) ->
+ tcInstTyVars VanillaTv tycon_tyvars `thenNF_Tc` \ (_, result_inst_tys, inst_env) ->
-- STEP 2
-- Check that at least one constructor has all the named fields
mk_inst_ty (tyvar, result_inst_ty)
| tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
- | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+ | otherwise = newTyVarTy liftedTypeKind -- Fresh type
in
- mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
+ mapNF_Tc mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
-- STEP 5
-- Typecheck the expression to be updated
let
record_ty = mkTyConApp tycon inst_tys
in
- tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
+ tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
-- STEP 6
-- Figure out the LIE we need. We have to generate some
-- dictionaries for the data type context, since we are going to
- -- do some construction.
+ -- do pattern matching over the data cons.
--
- -- What dictionaries do we need? For the moment we assume that all
- -- data constructors have the same context, and grab it from the first
- -- constructor. If they have varying contexts then we'd have to
- -- union the ones that could participate in the update.
+ -- What dictionaries do we need?
+ -- We just take the context of the type constructor
let
- (tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
- inst_env = mkTopTyVarSubst tyvars result_inst_tys
- theta' = substTheta inst_env theta
+ theta' = substTheta inst_env (tyConTheta tycon)
in
newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts ->
-- Phew!
- returnTc (RecordUpdOut record_expr' record_ty result_record_ty (map instToId dicts) rbinds',
+ returnTc (RecordUpdOut record_expr' record_ty result_record_ty rbinds',
mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie)
tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) ->
tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
+ traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenNF_Tc_`
split_fun_ty fun_ty (length args)
) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
-- (One can think of cases when the opposite order would give
-- a better error message.)
tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
- (tcSub res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) ->
+ (tcSubExp res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) ->
returnTc (co_fn <$> foldl HsApp fun' args',
lie_res `plusLIE` lie_fun `plusLIE` plusLIEs lie_args_s)
%* *
%************************************************************************
+tcId 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}
tcId :: Name -> NF_TcM (TcExpr, LIE, TcType)
tcId name -- Look up the Id and instantiate its type
= tcLookupId name `thenNF_Tc` \ id ->
- tcInstId id
+ case isDataConWrapId_maybe id of
+ Nothing -> loop (HsVar id) emptyLIE (idType id)
+ Just data_con -> inst_data_con id data_con
+ where
+ orig = OccurrenceOf name
+
+ loop (HsVar fun_id) lie fun_ty
+ | want_method_inst fun_ty
+ = tcInstType VanillaTv fun_ty `thenNF_Tc` \ (tyvars, theta, tau) ->
+ newMethodWithGivenTy orig fun_id
+ (mkTyVarTys tyvars) theta tau `thenNF_Tc` \ meth ->
+ loop (HsVar (instToId meth))
+ (unitLIE meth `plusLIE` lie) tau
+
+ loop fun lie fun_ty
+ | isSigmaTy fun_ty
+ = tcInstCall orig fun_ty `thenNF_Tc` \ (inst_fn, inst_lie, tau) ->
+ loop (inst_fn fun) (inst_lie `plusLIE` lie) tau
+
+ | otherwise
+ = returnNF_Tc (fun, lie, fun_ty)
+
+ want_method_inst fun_ty
+ | opt_NoMethodSharing = False
+ | otherwise = case tcSplitSigmaTy fun_ty of
+ (_,[],_) -> False -- Not overloaded
+ (_,theta,_) -> not (any isLinearPred theta)
+ -- This is a slight hack.
+ -- If f :: (%x :: T) => Int -> Int
+ -- Then if we have two separate calls, (f 3, f 4), we cannot
+ -- make a method constraint that then gets shared, thus:
+ -- let m = f %x in (m 3, m 4)
+ -- because that loses the linearity of the constraint.
+ -- The simplest thing to do is never to construct a method constraint
+ -- in the first place that has a linear implicit parameter in it.
+
+ -- We treat data constructors differently, because we have to generate
+ -- constraints for their silly theta, which no longer appears in
+ -- the type of dataConWrapId. It's dual to TcPat.tcConstructor
+ inst_data_con id data_con
+ = tcInstDataCon orig data_con `thenNF_Tc` \ (ty_args, ex_dicts, arg_tys, result_ty, stupid_lie, ex_lie, _) ->
+ returnNF_Tc (mkHsDictApp (mkHsTyApp (HsVar id) ty_args) ex_dicts,
+ stupid_lie `plusLIE` ex_lie,
+ mkFunTys arg_tys result_ty)
\end{code}
Typecheck expression which in most cases will be an Id.
+The expression can return a higher-ranked type, such as
+ (forall a. a->a) -> Int
+so we must create a HoleTyVarTy to pass in as the expected tyvar.
\begin{code}
tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, LIE, TcType)
tcExpr_id (HsVar name) = tcId name
-tcExpr_id expr = newTyVarTy openTypeKind `thenNF_Tc` \ id_ty ->
+tcExpr_id expr = newHoleTyVarTy `thenNF_Tc` \ id_ty ->
tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) ->
- returnTc (expr', lie_id, id_ty)
+ readHoleResult id_ty `thenTc` \ id_ty' ->
+ returnTc (expr', lie_id, id_ty')
\end{code}
= hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
exprSigCtxt expr
- = hang (ptext SLIT("In an expression with a type signature:"))
+ = hang (ptext SLIT("When checking the type signature of the expression:"))
4 (ppr expr)
listCtxt expr
projects / ghc-hetmet.git / blobdiff