import Id ( Id )
import TcType ( isTauTy )
import TcEnv ( checkWellStaged )
+import HsSyn ( nlHsApp )
import qualified DsMeta
#endif
import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
- HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar,
- nlHsApp )
-import TcHsSyn ( hsLitType, mkHsDictApp, mkHsTyApp, (<$>) )
+ HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar )
+import TcHsSyn ( hsLitType, (<$>) )
import TcRnMonad
-import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
- unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy )
+import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
+ unifyFunTys, zapToListTy, zapToTyConApp )
import BasicTypes ( isMarkedStrict )
import Inst ( InstOrigin(..),
newOverloadedLit, newMethodFromName, newIPDict,
- newDicts, newMethodWithGivenTy,
- instToId, tcInstCall, tcInstDataCon
- )
+ newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall )
import TcBinds ( tcBindsAndThen )
import TcEnv ( tcLookup, tcLookupId, checkProcLevel,
tcLookupDataCon, tcLookupGlobalId
import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) )
import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
import TcPat ( badFieldCon )
-import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType )
-import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
+import TcMType ( tcInstTyVars, tcInstType, newTyFlexiVarTy, zonkTcType, readMetaTyVar )
+import TcType ( Type, TcTyVar, TcType, TcSigmaType, TcRhoType, MetaDetails(..),
tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
- isSigmaTy, mkFunTy, mkFunTys,
- mkTyConApp, tyVarsOfTypes, isLinearPred,
- liftedTypeKind, openTypeKind,
+ isSigmaTy, mkFunTy, mkTyConApp, tyVarsOfTypes, isLinearPred,
tcSplitSigmaTy, tidyOpenType
)
-import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
+import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
+
import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId )
import Name ( Name )
-import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons )
-import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import TyCon ( TyCon, FieldLabel, tyConTyVars, tyConStupidTheta,
+ tyConDataCons, tyConFields )
+import Type ( zipTopTvSubst, mkTopTvSubst, substTheta, substTy )
import VarSet ( emptyVarSet, elemVarSet )
-import TysWiredIn ( boolTy )
+import TysWiredIn ( boolTy, parrTyCon, tupleTyCon )
import PrelNames ( enumFromName, enumFromThenName,
enumFromToName, enumFromThenToName,
enumFromToPName, enumFromThenToPName
import HscTypes ( TyThing(..) )
import SrcLoc ( Located(..), unLoc, getLoc )
import Util
+import Maybes ( catMaybes )
import Outputable
import FastString
tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty)
tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType)
-tcInferRho (L loc (HsVar name)) = addSrcSpan loc $
- do { (e,ty) <- tcId name; return (L loc e, ty)}
-tcInferRho expr = newHole `thenM` \ hole ->
- tcMonoExpr expr (Infer hole) `thenM` \ expr' ->
- readMutVar hole `thenM` \ rho_ty ->
- returnM (expr', rho_ty)
+tcInferRho (L loc (HsVar name)) = setSrcSpan loc $ do
+ { (e,_,ty) <- tcId name; return (L loc e, ty)}
+tcInferRho expr = tcInfer (tcMonoExpr expr)
\end{code}
-> TcM (LHsExpr TcId)
tcMonoExpr (L loc expr) res_ty
- = addSrcSpan loc (do { expr' <- tc_expr expr res_ty
+ = setSrcSpan loc (do { expr' <- tc_expr expr res_ty
; return (L loc expr') })
tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
tc_expr (HsVar name) res_ty
- = tcId name `thenM` \ (expr', id_ty) ->
- tcSubExp res_ty id_ty `thenM` \ co_fn ->
- returnM (co_fn <$> expr')
+ = do { (expr', _, id_ty) <- tcId name
+ ; co_fn <- tcSubExp res_ty id_ty
+ ; returnM (co_fn <$> expr') }
tc_expr (HsIPVar ip) res_ty
= -- Implicit parameters must have a *tau-type* not a
-- type scheme. We enforce this by creating a fresh
-- type variable as its type. (Because res_ty may not
-- be a tau-type.)
- newTyVarTy openTypeKind `thenM` \ ip_ty ->
+ newTyFlexiVarTy argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
extendLIE inst `thenM_`
tcSubExp res_ty ip_ty `thenM` \ co_fn ->
\begin{code}
tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = addErrCtxt (exprSigCtxt in_expr) $
+ = addErrCtxt (exprCtxt in_expr) $
tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') ->
- returnM (co_fn <$> unLoc expr')
- -- ToDo: nasty unLoc
+ returnM (co_fn <$> ExprWithTySigOut expr' poly_ty)
tc_expr (HsType ty) res_ty
= failWithTc (text "Can't handle type argument:" <+> ppr ty)
tc_expr (HsLit lit) res_ty = tcLit lit res_ty
tc_expr (HsOverLit lit) res_ty
- = zapExpectedType res_ty `thenM` \ res_ty' ->
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr ->
returnM (unLoc lit_expr) -- ToDo: nasty unLoc
tc_expr in_expr@(SectionL arg1 op) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn ->
tc_expr in_expr@(SectionR op arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn ->
tc_expr in_expr@(OpApp arg1 op fix arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
= tcBindsAndThen
glue
binds -- Bindings to check
- (tc_expr expr res_ty)
+ (setSrcSpan loc $ tc_expr expr res_ty)
where
glue bind expr = HsLet [bind] (L loc expr)
-tc_expr in_expr@(HsCase scrut matches) res_ty
- = addErrCtxt (caseCtxt in_expr) $
-
- -- Typecheck the case alternatives first.
+tc_expr in_expr@(HsCase scrut matches) exp_ty
+ = -- We used to typecheck the case alternatives first.
-- The case patterns tend to give good type info to use
-- when typechecking the scrutinee. For example
-- case (map f) of
-- (x:xs) -> ...
-- will report that map is applied to too few arguments
-
- tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') ->
-
- addErrCtxt (caseScrutCtxt scrut) (
- tcCheckRho scrut scrut_ty
- ) `thenM` \ scrut' ->
-
- returnM (HsCase scrut' matches')
- where
+ --
+ -- But now, in the GADT world, we need to typecheck the scrutinee
+ -- first, to get type info that may be refined in the case alternatives
+ addErrCtxt (caseScrutCtxt scrut)
+ (tcInferRho scrut) `thenM` \ (scrut', scrut_ty) ->
+
+ addErrCtxt (caseCtxt in_expr) $
+ tcMatchesCase match_ctxt scrut_ty matches exp_ty `thenM` \ matches' ->
+ returnM (HsCase scrut' matches')
+ where
match_ctxt = MC { mc_what = CaseAlt,
mc_body = tcMonoExpr }
= addErrCtxt (predCtxt pred) (
tcCheckRho pred boolTy ) `thenM` \ pred' ->
- zapExpectedType res_ty `thenM` \ res_ty' ->
+ zapExpectedType res_ty openTypeKind `thenM` \ res_ty' ->
-- C.f. the call to zapToType in TcMatches.tcMatches
tcCheckRho b1 res_ty' `thenM` \ b1' ->
returnM (HsIf pred' b1' b2')
tc_expr (HsDo do_or_lc stmts method_names _) res_ty
- = zapExpectedType res_ty `thenM` \ res_ty' ->
- -- All comprehensions yield a monotype
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ -- All comprehensions yield a monotype of kind *
tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') ->
returnM (HsDo do_or_lc stmts' methods' res_ty')
tcCheckRho expr elt_ty
tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
- = zapToPArrTy res_ty `thenM` \ elt_ty ->
- mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
- returnM (ExplicitPArr elt_ty exprs')
+ = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty
+ ; exprs' <- mappM (tc_elt elt_ty) exprs
+ ; return (ExplicitPArr elt_ty exprs') }
where
tc_elt elt_ty expr
- = addErrCtxt (parrCtxt expr) $
- tcCheckRho expr elt_ty
+ = addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty)
tc_expr (ExplicitTuple exprs boxity) res_ty
- = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
- tcCheckRhos exprs arg_tys `thenM` \ exprs' ->
- returnM (ExplicitTuple exprs' boxity)
+ = do { arg_tys <- zapToTyConApp (tupleTyCon boxity (length exprs)) res_ty
+ ; exprs' <- tcCheckRhos exprs arg_tys
+ ; return (ExplicitTuple exprs' boxity) }
tc_expr (HsProc pat cmd) res_ty
= tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
returnM (HsProc pat' cmd')
+
+tc_expr e@(HsArrApp _ _ _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
+
+tc_expr e@(HsArrForm _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tc_expr expr@(RecordCon con@(L _ con_name) rbinds) res_ty
+tc_expr expr@(RecordCon con@(L loc con_name) rbinds) res_ty
= addErrCtxt (recordConCtxt expr) $
- addLocM tcId con `thenM` \ (con_expr, con_tau) ->
+ addLocM tcId con `thenM` \ (con_expr, _, con_tau) ->
let
(_, record_ty) = tcSplitFunTys con_tau
(tycon, ty_args) = tcSplitTyConApp record_ty
-- The renamer has already checked that they
-- are all in scope
let
- bad_guys = [ addSrcSpan loc $ addErrTc (notSelector field_name)
+ bad_guys = [ setSrcSpan loc $ addErrTc (notSelector field_name)
| (L loc field_name, sel_id) <- field_names `zip` sel_ids,
not (isRecordSelector sel_id) -- Excludes class ops
]
let
-- It's OK to use the non-tc splitters here (for a selector)
sel_id : _ = sel_ids
- field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if
- tycon = fieldLabelTyCon field_lbl -- it's not a field label
- data_cons = tyConDataCons tycon
+ (tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
+ data_cons = tyConDataCons tycon -- it's not a field label
tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
+ tcInstTyVars tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
-- STEP 2
-- Check that at least one constructor has all the named fields
-- i.e. has an empty set of bad fields returned by badFields
checkTc (any (null . badFields rbinds) data_cons)
- (badFieldsUpd rbinds) `thenM_`
+ (badFieldsUpd rbinds) `thenM_`
-- STEP 3
-- Typecheck the update bindings.
-- WARNING: this code assumes that all data_cons in a common tycon
-- have FieldLabels abstracted over the same tyvars.
let
- upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds')
+ upd_field_lbls = recBindFields rbinds
con_field_lbls_s = map dataConFieldLabels data_cons
-- A constructor is only relevant to this process if
is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls
non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
- common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
+ common_tyvars = tyVarsOfTypes [ty | (fld,ty,_) <- tyConFields tycon,
+ fld `elem` non_upd_field_lbls]
- mk_inst_ty (tyvar, result_inst_ty)
+ mk_inst_ty tyvar result_inst_ty
| tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
- | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+-- gaw 2004 FIX?
+ | otherwise = newTyFlexiVarTy liftedTypeKind -- Fresh type
in
- mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys ->
+ zipWithM mk_inst_ty tycon_tyvars result_inst_tys `thenM` \ inst_tys ->
-- STEP 5
-- Typecheck the expression to be updated
-- What dictionaries do we need?
-- We just take the context of the type constructor
let
- theta' = substTheta inst_env (tyConTheta tycon)
+ theta' = substTheta inst_env (tyConStupidTheta tycon)
in
newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
extendLIEs dicts `thenM_`
tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- zapToPArrTy res_ty `thenM` \ elt_ty ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (PArrSeqOrigin seq)
tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- zapToPArrTy res_ty `thenM` \ elt_ty ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args
-> Expected TcRhoType -- Expected result type of application
- -> TcM (HsExpr TcId) -- Translated fun and args
+ -> TcM (HsExpr TcId) -- Translated fun and args
tcApp (L _ (HsApp e1 e2)) args res_ty
= tcApp e1 (e2:args) res_ty -- Accumulate the arguments
tcApp fun args res_ty
- = -- First type-check the function
- tcInferRho fun `thenM` \ (fun', fun_ty) ->
-
- addErrCtxt (wrongArgsCtxt "too many" fun args) (
- traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_`
- split_fun_ty fun_ty (length args)
- ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
-
- -- Unify with expected result before (was: after) type-checking the args
- -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty).
- -- This is when we might detect a too-few args situation.
- -- (One can think of cases when the opposite order would give
- -- a better error message.)
- -- [March 2003: I'm experimenting with putting this first. Here's an
- -- example where it actually makes a real difference
- -- class C t a b | t a -> b
- -- instance C Char a Bool
- --
- -- data P t a = forall b. (C t a b) => MkP b
- -- data Q t = MkQ (forall a. P t a)
-
- -- f1, f2 :: Q Char;
- -- f1 = MkQ (MkP True)
- -- f2 = MkQ (MkP True :: forall a. P Char a)
- --
- -- With the change, f1 will type-check, because the 'Char' info from
- -- the signature is propagated into MkQ's argument. With the check
- -- in the other order, the extra signature in f2 is reqd.]
-
- addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
- (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
+ = do { (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
+
+ -- Extract its argument types
+ ; (expected_arg_tys, actual_res_ty)
+ <- addErrCtxt (wrongArgsCtxt "too many" fun args) $ do
+ { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau))
+ ; unifyFunTys (length args) fun_tau }
+
+
+ ; case res_ty of
+ Check _ -> do -- Connect to result type first
+ -- See Note [Push result type in]
+ { co_fn <- tcResult fun args res_ty actual_res_ty
+ ; the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; traceTc (text "tcApp: check" <+> vcat [ppr fun <+> ppr args,
+ ppr the_app', ppr actual_res_ty])
+ ; returnM (co_fn <$> the_app') }
+
+ Infer _ -> do -- Type check args first, then
+ -- refine result type, then do tcResult
+ { the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; actual_res_ty' <- refineResultTy fun_tvs actual_res_ty
+ ; co_fn <- tcResult fun args res_ty actual_res_ty'
+ ; traceTc (text "tcApp: infer" <+> vcat [ppr fun <+> ppr args, ppr the_app',
+ ppr actual_res_ty, ppr actual_res_ty'])
+ ; returnM (co_fn <$> the_app') }
+ }
+
+-- Note [Push result type in]
+--
+-- Unify with expected result before (was: after) type-checking the args
+-- so that the info from res_ty (was: args) percolates to args (was actual_res_ty).
+-- This is when we might detect a too-few args situation.
+-- (One can think of cases when the opposite order would give
+-- a better error message.)
+-- [March 2003: I'm experimenting with putting this first. Here's an
+-- example where it actually makes a real difference
+-- class C t a b | t a -> b
+-- instance C Char a Bool
+--
+-- data P t a = forall b. (C t a b) => MkP b
+-- data Q t = MkQ (forall a. P t a)
- -- Now typecheck the args
- mappM (tcArg fun)
- (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
+-- f1, f2 :: Q Char;
+-- f1 = MkQ (MkP True)
+-- f2 = MkQ (MkP True :: forall a. P Char a)
+--
+-- With the change, f1 will type-check, because the 'Char' info from
+-- the signature is propagated into MkQ's argument. With the check
+-- in the other order, the extra signature in f2 is reqd.]
+
+----------------
+tcFun :: LHsExpr Name -> TcM (LHsExpr TcId, [TcTyVar], TcRhoType)
+-- Instantiate the function, returning the type variables used
+-- If the function isn't simple, infer its type, and return no
+-- type variables
+tcFun (L loc (HsVar f)) = setSrcSpan loc $ do
+ { (fun', tvs, fun_tau) <- tcId f
+ ; return (L loc fun', tvs, fun_tau) }
+tcFun fun = do { (fun', fun_tau) <- tcInfer (tcMonoExpr fun)
+ ; return (fun', [], fun_tau) }
+
+----------------
+tcArgs :: LHsExpr Name -- The function (for error messages)
+ -> LHsExpr TcId -- The function (to build into result)
+ -> [LHsExpr Name] -> [TcSigmaType] -- Actual arguments and expected arg types
+ -> TcM (HsExpr TcId) -- Resulting application
+
+tcArgs fun fun' args expected_arg_tys
+ = do { args' <- mappM (tcArg fun) (zip3 args expected_arg_tys [1..])
+ ; return (unLoc (foldl mkHsApp fun' args')) }
- returnM (co_fn <$> unLoc (foldl mkHsApp fun' args'))
+tcArg :: LHsExpr Name -- The function (for error messages)
+ -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (LHsExpr TcId) -- Resulting argument
+tcArg fun (arg, ty, arg_no) = addErrCtxt (funAppCtxt fun arg arg_no)
+ (tcCheckSigma arg ty)
+----------------
+tcResult fun args res_ty actual_res_ty
+ = addErrCtxtM (checkArgsCtxt fun args res_ty actual_res_ty)
+ (tcSubExp res_ty actual_res_ty)
+----------------
-- If an error happens we try to figure out whether the
-- function has been given too many or too few arguments,
-- and say so.
-- The ~(Check...) is because in the Infer case the tcSubExp
-- definitely won't fail, so we can be certain we're in the Check branch
-checkArgsCtxt fun args ~(Check expected_res_ty) actual_res_ty tidy_env
+checkArgsCtxt fun args (Infer _) actual_res_ty tidy_env
+ = return (tidy_env, ptext SLIT("Urk infer"))
+
+checkArgsCtxt fun args (Check expected_res_ty) actual_res_ty tidy_env
= zonkTcType expected_res_ty `thenM` \ exp_ty' ->
zonkTcType actual_res_ty `thenM` \ act_ty' ->
let
in
returnM (env2, message)
-
-split_fun_ty :: TcRhoType -- The type of the function
- -> Int -- Number of arguments
- -> TcM ([TcType], -- Function argument types
- TcType) -- Function result types
-
-split_fun_ty fun_ty 0
- = returnM ([], fun_ty)
-
-split_fun_ty fun_ty n
- = -- Expect the function to have type A->B
- unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) ->
- split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) ->
- returnM (arg_ty:arg_tys, final_res_ty)
-\end{code}
-
-\begin{code}
-tcArg :: LHsExpr Name -- The function (for error messages)
- -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
- -> TcM (LHsExpr TcId) -- Resulting argument
-
-tcArg the_fun (arg, expected_arg_ty, arg_no)
- = addErrCtxt (funAppCtxt the_fun arg arg_no) $
- tcCheckSigma arg expected_arg_ty
+----------------
+refineResultTy :: [TcTyVar] -- Newly instantiated meta-tyvars of the function
+ -> TcType -- Result type, instantiated with those tyvars
+ -> TcM TcType -- Refined result type
+-- De-wobblify the result type, by taking account what we learned
+-- from type-checking the arguments. Just one level of de-wobblification
+-- though. What a hack!
+refineResultTy tvs res_ty
+ = do { mb_prs <- mapM mk_pr tvs
+ ; let subst = mkTopTvSubst (catMaybes mb_prs)
+ ; return (substTy subst res_ty) }
+ where
+ mk_pr tv = do { details <- readMetaTyVar tv
+ ; case details of
+ Indirect ty -> return (Just (tv,ty))
+ other -> return Nothing
+ }
\end{code}
b) perhaps fewer separated lambdas
\begin{code}
-tcId :: Name -> TcM (HsExpr TcId, TcRhoType)
+tcId :: Name -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ -- Return the type variables at which the function
+ -- is instantiated, as well as the translated variable and its type
+
tcId name -- Look up the Id and instantiate its type
- = -- First check whether it's a DataCon
- -- Reason: we must not forget to chuck in the
- -- constraints from their "silly context"
- tcLookup name `thenM` \ thing ->
+ = tcLookup name `thenM` \ thing ->
case thing of {
- AGlobal (ADataCon data_con) -> inst_data_con data_con
- ; AGlobal (AnId id) -> loop (HsVar id) (idType id)
+ AGlobal (AnId id) -> instantiate id
-- A global cannot possibly be ill-staged
-- nor does it need the 'lifting' treatment
- ; ATcId id th_level proc_level -> tc_local_id id th_level proc_level
- ; other -> pprPanic "tcId" (ppr name $$ ppr thing)
+ ; AGlobal (ADataCon con) -- Similar, but instantiate the stupid theta too
+ -> do { (expr, tvs, tau) <- instantiate (dataConWrapId con)
+ ; tcInstStupidTheta con (mkTyVarTys tvs)
+ -- Remember to chuck in the constraints from the "silly context"
+ ; return (expr, tvs, tau) }
+
+ ; ATcId id th_level proc_level
+ -> do { checkProcLevel id proc_level
+ ; tc_local_id id th_level }
+
+ ; other -> pprPanic "tcId" (ppr name $$ ppr thing)
}
where
#ifndef GHCI
- tc_local_id id th_bind_lvl proc_lvl -- Non-TH case
- = checkProcLevel id proc_lvl `thenM_`
- loop (HsVar id) (idType id)
+ tc_local_id id th_bind_lvl -- Non-TH case
+ = instantiate id
#else /* GHCI and TH is on */
- tc_local_id id th_bind_lvl proc_lvl -- TH case
- = checkProcLevel id proc_lvl `thenM_`
-
- -- Check for cross-stage lifting
+ tc_local_id id th_bind_lvl -- TH case
+ = -- Check for cross-stage lifting
getStage `thenM` \ use_stage ->
case use_stage of
Brack use_lvl ps_var lie_var
| use_lvl > th_bind_lvl
-> -- E.g. \x -> [| h x |]
-- We must behave as if the reference to x was
-
-- h $(lift x)
-- We use 'x' itself as the splice proxy, used by
-- the desugarer to stitch it all back together.
readMutVar ps_var `thenM` \ ps ->
writeMutVar ps_var ((name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
- returnM (HsVar id, id_ty))
+ returnM (HsVar id, [], id_ty))
other ->
checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
- loop (HsVar id) (idType id)
+ instantiate id
#endif /* GHCI */
- loop (HsVar fun_id) fun_ty
+ instantiate :: TcId -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ instantiate fun_id = loop (HsVar fun_id) [] (idType fun_id)
+
+ loop (HsVar fun_id) tvs fun_ty
| want_method_inst fun_ty
- = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ = tcInstType fun_ty `thenM` \ (tyvars, theta, tau) ->
newMethodWithGivenTy orig fun_id
(mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
- loop (HsVar meth_id) tau
+ loop (HsVar meth_id) (tvs ++ tyvars) tau
- loop fun fun_ty
+ loop fun tvs fun_ty
| isSigmaTy fun_ty
- = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
- loop (inst_fn <$> fun) tau
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, new_tvs, tau) ->
+ loop (inst_fn <$> fun) (tvs ++ new_tvs) tau
| otherwise
- = returnM (fun, fun_ty)
+ = returnM (fun, tvs, fun_ty)
-- Hack Alert (want_method_inst)!
-- If f :: (%x :: T) => Int -> Int
(_,[],_) -> False -- Not overloaded
(_,theta,_) -> not (any isLinearPred theta)
-
- -- We treat data constructors differently, because we have to generate
- -- constraints for their silly theta, which no longer appears in
- -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs
- -- It's dual to TcPat.tcConstructor
- inst_data_con data_con
- = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
- extendLIEs ex_dicts `thenM_`
- getSrcSpanM `thenM` \ loc ->
- returnM (unLoc (mkHsDictApp (mkHsTyApp (L loc (HsVar (dataConWrapId data_con))) ty_args)
- (map instToId ex_dicts)),
- mkFunTys arg_tys result_ty)
- -- ToDo: nasty loc/unloc stuff here
-
orig = OccurrenceOf name
\end{code}
tcRecordBinds tycon ty_args rbinds
= mappM do_bind rbinds
where
- tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
+ tenv = zipTopTvSubst (tyConTyVars tycon) ty_args
- do_bind (L loc field_lbl_name, rhs)
- = addErrCtxt (fieldCtxt field_lbl_name) $
- tcLookupId field_lbl_name `thenM` \ sel_id ->
+ do_bind (L loc field_lbl, rhs)
+ = addErrCtxt (fieldCtxt field_lbl) $
let
- field_lbl = recordSelectorFieldLabel sel_id
- field_ty = substTy tenv (fieldLabelType field_lbl)
+ field_ty = tyConFieldType tycon field_lbl
+ field_ty' = substTy tenv field_ty
in
+ tcCheckSigma rhs field_ty' `thenM` \ rhs' ->
+ tcLookupId field_lbl `thenM` \ sel_id ->
ASSERT( isRecordSelector sel_id )
+ returnM (L loc sel_id, rhs')
+
+tyConFieldType :: TyCon -> FieldLabel -> Type
+tyConFieldType tycon field_lbl
+ = case [ty | (f,ty,_) <- tyConFields tycon, f == field_lbl] of
+ (ty:other) -> ASSERT( null other) ty
-- This lookup and assertion will surely succeed, because
-- we check that the fields are indeed record selectors
-- before calling tcRecordBinds
- ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl )
- -- The caller of tcRecordBinds has already checked
- -- that all the fields come from the same type
-
- tcCheckSigma rhs field_ty `thenM` \ rhs' ->
-
- returnM (L loc sel_id, rhs')
badFields rbinds data_con
= filter (not . (`elem` field_names)) (recBindFields rbinds)
where
- field_names = map fieldLabelName (dataConFieldLabels data_con)
+ field_names = dataConFieldLabels data_con
checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM ()
checkMissingFields data_con rbinds
missing_s_fields
= [ fl | (fl, str) <- field_info,
isMarkedStrict str,
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
missing_ns_fields
= [ fl | (fl, str) <- field_info,
not (isMarkedStrict str),
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
field_names_used = recBindFields rbinds
caseScrutCtxt expr
= hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-exprSigCtxt expr
- = hang (ptext SLIT("In the type signature of the expression:"))
- 4 (ppr expr)
-
exprCtxt expr
= hang (ptext SLIT("In the expression:")) 4 (ppr expr)