\section[TcExpr]{Typecheck an expression}
\begin{code}
-#include "HsVersions.h"
-
module TcExpr ( tcExpr, tcStmt, tcId ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import HsSyn ( HsExpr(..), Stmt(..), DoOrListComp(..),
- HsBinds(..), MonoBinds(..),
- SYN_IE(RecFlag), nonRecursive,
- ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds,
- Match, Fake, InPat, OutPat, HsType, Fixity,
- pprParendExpr, failureFreePat, collectPatBinders )
-import RnHsSyn ( SYN_IE(RenamedHsExpr),
- SYN_IE(RenamedStmt), SYN_IE(RenamedRecordBinds)
+import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
+ HsBinds(..), Stmt(..), DoOrListComp(..),
+ failureFreePat, collectPatBinders
+ )
+import RnHsSyn ( RenamedHsExpr,
+ RenamedStmt, RenamedRecordBinds
)
-import TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcStmt),
- SYN_IE(TcRecordBinds),
+import TcHsSyn ( TcExpr, TcStmt,
+ TcRecordBinds,
mkHsTyApp
)
import TcMonad
+import BasicTypes ( RecFlag(..) )
+
import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- SYN_IE(LIE), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
+ LIE, emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
newMethod, newMethodWithGivenTy, newDicts )
import TcBinds ( tcBindsAndThen, checkSigTyVars )
-import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
- tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars,
- tcExtendGlobalTyVars, tcLookupGlobalValueMaybe
+import TcEnv ( TcIdOcc(..), tcInstId,
+ tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
+ tcLookupGlobalValueByKey, newMonoIds,
+ tcExtendGlobalTyVars, tcLookupGlobalValueMaybe,
+ tcLookupTyCon
)
-import SpecEnv ( SpecEnv )
import TcMatches ( tcMatchesCase, tcMatchExpected )
import TcMonoType ( tcHsType )
import TcPat ( tcPat )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( TcIdOcc(..), SYN_IE(TcType), TcMaybe(..),
- tcInstId, tcInstType, tcInstSigTcType, tcInstTyVars,
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( TcType, TcMaybe(..),
+ tcInstType, tcInstSigTcType, tcInstTyVars,
tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy,
- newTyVarTy, newTyVarTys, zonkTcTyVars, zonkTcType )
+ newTyVarTy, newTyVarTys, zonkTcType )
import TcKind ( TcKind )
-import Class ( SYN_IE(Class) )
+import Class ( Class )
import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType )
import Id ( idType, dataConFieldLabels, dataConSig, recordSelectorFieldLabel,
isRecordSelector,
- SYN_IE(Id), GenId
+ Id
)
import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
import Name ( Name{-instance Eq-} )
-import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy,
- getTyVar_maybe, getFunTy_maybe, instantiateTy, applyTyCon,
- splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy,
- isTauTy, mkFunTys, tyVarsOfType, tyVarsOfTypes, getForAllTy_maybe,
- getAppDataTyCon, maybeAppDataTyCon
+import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys,
+ splitFunTy_maybe, splitFunTys,
+ mkTyConApp,
+ splitForAllTys, splitRhoTy, splitSigmaTy,
+ isTauTy, tyVarsOfType, tyVarsOfTypes,
+ splitForAllTy_maybe, splitAlgTyConApp, splitAlgTyConApp_maybe
)
-import TyVar ( GenTyVar, SYN_IE(TyVarSet), unionTyVarSets, elementOfTyVarSet, mkTyVarSet )
-import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy, realWorldTy
+import TyVar ( emptyTyVarEnv, zipTyVarEnv,
+ elementOfTyVarSet, mkTyVarSet, tyVarSetToList
)
-import TysWiredIn ( addrTy,
- boolTy, charTy, stringTy, mkListTy,
- mkTupleTy, mkPrimIoTy, stDataCon
+import TyCon ( tyConDataCons )
+import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
+ floatPrimTy, addrPrimTy
)
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy )
+import TysWiredIn ( boolTy, charTy, stringTy )
+import PrelInfo ( ioTyCon_NAME )
+import Unify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy )
import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
enumFromClassOpKey, enumFromThenClassOpKey,
enumFromToClassOpKey, enumFromThenToClassOpKey,
thenMClassOpKey, zeroClassOpKey, returnMClassOpKey
)
-import Outputable ( speakNth, interpp'SP, Outputable(..) )
-import PprType ( GenType, GenTyVar ) -- Instances
+import Outputable
import Maybes ( maybeToBool )
-import Pretty
import ListSetOps ( minusList )
import Util
\end{code}
\begin{code}
tcExpr (HsVar name) res_ty
= tcId name `thenNF_Tc` \ (expr', lie, id_ty) ->
- unifyTauTy id_ty res_ty `thenTc_`
+ unifyTauTy res_ty id_ty `thenTc_`
-- Check that the result type doesn't have any nested for-alls.
-- For example, a "build" on its own is no good; it must be
tcExpr (HsLit lit@(HsLitLit s)) res_ty
= tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
newDicts (LitLitOrigin (_UNPK_ s))
- [(cCallableClass, res_ty)] `thenNF_Tc` \ (dicts, _) ->
+ [(cCallableClass, [res_ty])] `thenNF_Tc` \ (dicts, _) ->
returnTc (HsLitOut lit res_ty, dicts)
\end{code}
\begin{code}
tcExpr (HsLit lit@(HsCharPrim c)) res_ty
- = unifyTauTy charPrimTy res_ty `thenTc_`
+ = unifyTauTy res_ty charPrimTy `thenTc_`
returnTc (HsLitOut lit charPrimTy, emptyLIE)
tcExpr (HsLit lit@(HsStringPrim s)) res_ty
- = unifyTauTy addrPrimTy res_ty `thenTc_`
+ = unifyTauTy res_ty addrPrimTy `thenTc_`
returnTc (HsLitOut lit addrPrimTy, emptyLIE)
tcExpr (HsLit lit@(HsIntPrim i)) res_ty
- = unifyTauTy intPrimTy res_ty `thenTc_`
+ = unifyTauTy res_ty intPrimTy `thenTc_`
returnTc (HsLitOut lit intPrimTy, emptyLIE)
tcExpr (HsLit lit@(HsFloatPrim f)) res_ty
- = unifyTauTy floatPrimTy res_ty `thenTc_`
+ = unifyTauTy res_ty floatPrimTy `thenTc_`
returnTc (HsLitOut lit floatPrimTy, emptyLIE)
tcExpr (HsLit lit@(HsDoublePrim d)) res_ty
- = unifyTauTy doublePrimTy res_ty `thenTc_`
+ = unifyTauTy res_ty doublePrimTy `thenTc_`
returnTc (HsLitOut lit doublePrimTy, emptyLIE)
\end{code}
\begin{code}
tcExpr (HsLit lit@(HsChar c)) res_ty
- = unifyTauTy charTy res_ty `thenTc_`
+ = unifyTauTy res_ty charTy `thenTc_`
returnTc (HsLitOut lit charTy, emptyLIE)
tcExpr (HsLit lit@(HsString str)) res_ty
- = unifyTauTy stringTy res_ty `thenTc_`
+ = unifyTauTy res_ty stringTy `thenTc_`
returnTc (HsLitOut lit stringTy, emptyLIE)
\end{code}
tcExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go
= tcExpr expr res_ty
-tcExpr (NegApp expr neg) res_ty = tcExpr (HsApp neg expr) res_ty
+-- perform the negate *before* overloading the integer, since the case
+-- of minBound on Ints fails otherwise. Could be done elsewhere, but
+-- convenient to do it here.
+
+tcExpr (NegApp (HsLit (HsInt i)) neg) res_ty
+ = tcExpr (HsLit (HsInt (-i))) res_ty
+
+tcExpr (NegApp expr neg) res_ty
+ = tcExpr (HsApp neg expr) res_ty
tcExpr (HsLam match) res_ty
- = tcMatchExpected res_ty match `thenTc` \ (match',lie) ->
+ = tcMatchExpected [] res_ty match `thenTc` \ (match',lie) ->
returnTc (HsLam match', lie)
tcExpr (HsApp e1 e2) res_ty = accum e1 [e2]
tcAddErrCtxt (sectionRAppCtxt in_expr) $
split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcExpr expr arg2_ty `thenTc` \ (expr',lie2) ->
- unifyTauTy (mkFunTy arg1_ty op_res_ty) res_ty `thenTc_`
+ unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_`
returnTc (SectionR op' expr', lie1 `plusLIE` lie2)
\end{code}
= -- Get the callable and returnable classes.
tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass ->
+ tcLookupTyCon ioTyCon_NAME `thenTc` \ (_,_,ioTyCon) ->
let
new_arg_dict (arg, arg_ty)
= newDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
- [(cCallableClass, arg_ty)] `thenNF_Tc` \ (arg_dicts, _) ->
+ [(cCallableClass, [arg_ty])] `thenNF_Tc` \ (arg_dicts, _) ->
returnNF_Tc arg_dicts -- Actually a singleton bag
result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -}
tcExprs args ty_vars `thenTc` \ (args', args_lie) ->
-- The argument types can be unboxed or boxed; the result
- -- type must, however, be boxed since it's an argument to the PrimIO
+ -- type must, however, be boxed since it's an argument to the IO
-- type constructor.
newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ result_ty ->
- unifyTauTy (mkPrimIoTy result_ty) res_ty `thenTc_`
+ let
+ io_result_ty = mkTyConApp ioTyCon [result_ty]
+ in
+ case tyConDataCons ioTyCon of { [ioDataCon] ->
+ unifyTauTy res_ty io_result_ty `thenTc_`
-- Construct the extra insts, which encode the
-- constraints on the argument and result types.
mapNF_Tc new_arg_dict (zipEqual "tcExpr:CCall" args ty_vars) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) ->
+ newDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
- returnTc (HsApp (HsVar (RealId stDataCon) `TyApp` [realWorldTy, result_ty])
- (CCall lbl args' may_gc is_asm result_ty),
+ returnTc (HsApp (HsVar (RealId ioDataCon) `TyApp` [result_ty])
+ (CCall lbl args' may_gc is_asm io_result_ty),
-- do the wrapping in the newtype constructor here
foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie)
+ }
\end{code}
\begin{code}
returnTc (expr', lie)
combiner is_rec bind expr = HsLet (MonoBind bind [] is_rec) expr
-tcExpr in_expr@(HsCase expr matches src_loc) res_ty
- = tcAddSrcLoc src_loc $
- newTyVarTy mkTypeKind `thenNF_Tc` \ expr_ty ->
- tcExpr expr expr_ty `thenTc` \ (expr',lie1) ->
+tcExpr in_expr@(HsCase scrut matches src_loc) res_ty
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (caseCtxt in_expr) $
- tcAddErrCtxt (caseCtxt in_expr) $
- tcMatchesCase (mkFunTy expr_ty res_ty) matches
- `thenTc` \ (matches',lie2) ->
+ -- 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
- returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2)
+ tcMatchesCase res_ty matches `thenTc` \ (scrut_ty, matches', lie2) ->
+
+ tcAddErrCtxt (caseScrutCtxt scrut) (
+ tcExpr scrut scrut_ty
+ ) `thenTc` \ (scrut',lie1) ->
+
+ returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
tcExpr (HsIf pred b1 b2 src_loc) res_ty
= tcAddSrcLoc src_loc $
tcAddErrCtxt (predCtxt pred) (
tcExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
- tcAddErrCtxt (branchCtxt b1 b2) $
tcExpr b1 res_ty `thenTc` \ (b1',lie2) ->
tcExpr b2 res_ty `thenTc` \ (b2',lie3) ->
returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3))
tcExpr expr elt_ty
tcExpr (ExplicitTuple exprs) res_ty
- -- ToDo: more direct way of testing if res_ty is a tuple type (cf. unifyListTy)?
- = mapNF_Tc (\ _ -> newTyVarTy mkBoxedTypeKind) [1..len] `thenNF_Tc` \ ty_vars ->
- unifyTauTy (mkTupleTy len ty_vars) res_ty `thenTc_`
- mapAndUnzipTc (\ (expr,ty_var) -> tcExpr expr ty_var)
- (exprs `zip` ty_vars) -- we know they're of equal length.
+ = unifyTupleTy (length exprs) res_ty `thenTc` \ arg_tys ->
+ mapAndUnzipTc (\ (expr, arg_ty) -> tcExpr expr arg_ty)
+ (exprs `zip` arg_tys) -- we know they're of equal length.
`thenTc` \ (exprs', lies) ->
returnTc (ExplicitTuple exprs', plusLIEs lies)
- where
- len = length exprs
-tcExpr (RecordCon (HsVar con) rbinds) res_ty
- = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+tcExpr (RecordCon con_name _ rbinds) res_ty
+ = tcLookupGlobalValue con_name `thenNF_Tc` \ con_id ->
+ tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
let
- (_, record_ty) = splitFunTy con_tau
+ (_, record_ty) = splitFunTys con_tau
in
-- Con is syntactically constrained to be a data constructor
- ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) )
- unifyTauTy record_ty res_ty `thenTc_`
+ ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty ) )
+ unifyTauTy res_ty record_ty `thenTc_`
-- Check that the record bindings match the constructor
- tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
let
bad_fields = badFields rbinds con_id
in
- checkTc (null bad_fields) (badFieldsCon con bad_fields) `thenTc_`
+ checkTc (null bad_fields) (badFieldsCon con_id bad_fields) `thenTc_`
-- Typecheck the record bindings
-- (Do this after checkRecordFields in case there's a field that
-- doesn't match the constructor.)
tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
- returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie)
+ returnTc (RecordCon (RealId con_id) con_expr rbinds', con_lie `plusLIE` rbinds_lie)
-- The main complication with RecordUpd is that we need to explicitly
tcLookupGlobalValueMaybe first_field_name `thenNF_Tc` \ maybe_sel_id ->
(case maybe_sel_id of
Just sel_id | isRecordSelector sel_id -> returnTc sel_id
- other -> failTc (notSelector first_field_name)
+ other -> failWithTc (notSelector first_field_name)
) `thenTc` \ sel_id ->
let
- (_, tau) = splitForAllTy (idType sel_id)
- Just (data_ty, _) = getFunTy_maybe tau -- Must succeed since sel_id is a selector
- (tycon, _, data_cons) = getAppDataTyCon data_ty
+ (_, tau) = splitForAllTys (idType sel_id)
+ Just (data_ty, _) = splitFunTy_maybe tau -- Must succeed since sel_id is a selector
+ (tycon, _, data_cons) = splitAlgTyConApp data_ty
(con_tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
in
- tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, result_inst_env) ->
+ tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) ->
-- STEP 2
-- Check for bad fields
-- (Do this after checking for bad fields in case there's a field that
-- doesn't match the constructor.)
let
- result_record_ty = applyTyCon tycon result_inst_tys
+ result_record_ty = mkTyConApp tycon result_inst_tys
in
- unifyTauTy result_record_ty res_ty `thenTc_`
+ unifyTauTy res_ty result_record_ty `thenTc_`
tcRecordBinds result_record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
-- STEP 4
-- STEP 5
-- Typecheck the expression to be updated
let
- record_ty = applyTyCon tycon inst_tys
+ record_ty = mkTyConApp tycon inst_tys
in
tcExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
-- union the ones that could participate in the update.
let
(tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
- inst_env = zipEqual "tcExpr:RecordUpd" tyvars result_inst_tys
+ inst_env = zipTyVarEnv tyvars result_inst_tys
in
tcInstTheta inst_env theta `thenNF_Tc` \ theta' ->
newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
tcExpr (ArithSeqIn seq@(From expr)) res_ty
= unifyListTy res_ty `thenTc` \ elt_ty ->
- tcExpr expr elt_ty `thenTc` \ (expr', lie1) ->
+ tcExpr expr elt_ty `thenTc` \ (expr', lie1) ->
tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
let
(sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
in
- unifyTauTy sig_tau' res_ty `thenTc_`
- -- Type check the expression, *after* we've incorporated the signature
- -- info into res_ty
- tcExpr expr res_ty `thenTc` \ (texpr, lie) ->
+ -- Type check the expression, expecting the signature type
+ tcExtendGlobalTyVars sig_tyvars' (
+ tcExpr expr sig_tau'
+ ) `thenTc` \ (texpr, lie) ->
-- Check the type variables of the signature,
-- *after* typechecking the expression
- checkSigTyVars sig_tyvars' sig_tau' `thenTc_`
+ checkSigTyVars sig_tyvars' sig_tau' `thenTc` \ zonked_sig_tyvars ->
-- Check overloading constraints
newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) ->
tcSimplifyAndCheck
- (mkTyVarSet sig_tyvars')
- sig_dicts lie `thenTc_`
+ (ptext SLIT("the type signature") <+> quotes (ppr sigma_sig))
+ (mkTyVarSet zonked_sig_tyvars)
+ sig_dicts lie
+ `thenTc_`
+
+ -- Now match the signature type with res_ty.
+ -- We must not do this earlier, because res_ty might well
+ -- mention variables free in the environment, and we'd get
+ -- bogus complaints about not being able to for-all the
+ -- sig_tyvars
+ unifyTauTy res_ty sig_tau' `thenTc_`
-- If everything is ok, return the stuff unchanged, except for
-- the effect of any substutions etc. We simply discard the
other -> newTyVarTy mkTypeKind `thenNF_Tc` \ id_ty ->
tcExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
returnTc (id_expr', lie_id, id_ty)
-
-
---ToDo: move to Unify?
-unifyListTy :: TcType s -- expected list type
- -> TcM s (TcType s) -- list element type
-unifyListTy res_ty
- -- ToDo: more direct way of testing if res_ty is a list type (cf. unifyFunTy)?
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ elt_ty ->
- unifyTauTy (mkListTy elt_ty) res_ty `thenTc_`
-
- -- This zonking makes the returned type as informative
- -- as possible.
- zonkTcType elt_ty `thenNF_Tc` \ elt_ty' ->
- returnTc elt_ty'
\end{code}
%************************************************************************
tcApp fun args res_ty
= -- First type-check the function
- tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) ->
+ tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) ->
- tcAddErrCtxt (tooManyArgsCtxt fun) (
+ tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
split_fun_ty fun_ty (length args)
- ) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
+ ) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
-- Unify with expected result before type-checking the args
- unifyTauTy res_ty actual_result_ty `thenTc_`
+ -- This is when we might detect a too-few args situation
+ tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) (
+ unifyTauTy res_ty actual_result_ty
+ ) `thenTc_`
-- Now typecheck the args
- mapAndUnzipTc tcArg (zipEqual "tcApp" args expected_arg_tys) `thenTc` \ (args', lie_args_s) ->
+ mapAndUnzipTc (tcArg fun)
+ (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) ->
-- Check that the result type doesn't have any nested for-alls.
-- For example, a "build" on its own is no good; it must be applied to something.
checkTc (isTauTy actual_result_ty)
- (lurkingRank2Err fun fun_ty) `thenTc_`
+ (lurkingRank2Err fun fun_ty) `thenTc_`
returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s)
+-- If an error happens we try to figure out whether the
+-- function has been given too many or too few arguments,
+-- and say so
+checkArgsCtxt fun args expected_res_ty actual_res_ty
+ = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' ->
+ zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' ->
+ let
+ (exp_args, _) = splitFunTys exp_ty'
+ (act_args, _) = splitFunTys act_ty'
+ message | length exp_args < length act_args = wrongArgsCtxt "too few" fun args
+ | length exp_args > length act_args = wrongArgsCtxt "too many" fun args
+ | otherwise = appCtxt fun args
+ in
+ returnNF_Tc message
+
+
split_fun_ty :: TcType s -- The type of the function
-> Int -- Number of arguments
-> TcM s ([TcType s], -- Function argument types
\end{code}
\begin{code}
-tcArg :: (RenamedHsExpr, TcType s) -- Actual argument and expected arg type
+tcArg :: RenamedHsExpr -- The function (for error messages)
+ -> (RenamedHsExpr, TcType s, Int) -- Actual argument and expected arg type
-> TcM s (TcExpr s, LIE s) -- Resulting argument and LIE
-tcArg (arg,expected_arg_ty)
- | not (maybeToBool (getForAllTy_maybe expected_arg_ty))
+tcArg the_fun (arg, expected_arg_ty, arg_no)
+ = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
+ tcPolyExpr (ptext SLIT("argument type of") <+> quotes (ppr the_fun))
+ arg expected_arg_ty
+
+
+-- tcPolyExpr is like tcExpr, except that the expected type
+-- can be a polymorphic one.
+tcPolyExpr :: SDoc -- Just for error messages
+ -> RenamedHsExpr
+ -> TcType s -- Expected type
+ -> TcM s (TcExpr s, LIE s) -- Resulting type and LIE
+
+tcPolyExpr str arg expected_arg_ty
+ | not (maybeToBool (splitForAllTy_maybe expected_arg_ty))
= -- The ordinary, non-rank-2 polymorphic case
tcExpr arg expected_arg_ty
let
(sig_theta, sig_tau) = splitRhoTy sig_rho
in
- ASSERT( null sig_theta ) -- And expected_tyvars are all DontBind things
-
-- Type-check the arg and unify with expected type
tcExpr arg sig_tau `thenTc` \ (arg', lie_arg) ->
-- Conclusion: include the free vars of the expected arg type in the
-- list of "free vars" for the signature check.
- tcAddErrCtxt (rank2ArgCtxt arg expected_arg_ty) (
- tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) (
- checkSigTyVars sig_tyvars sig_tau
- ) `thenTc_`
+ tcExtendGlobalTyVars (tyVarSetToList (tyVarsOfType expected_arg_ty)) $
+
+ checkSigTyVars sig_tyvars sig_tau `thenTc` \ zonked_sig_tyvars ->
+ newDicts SignatureOrigin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) ->
+ -- ToDo: better origin
- -- Check that there's no overloading involved
- -- Even if there isn't, there may be some Insts which mention the expected_tyvars,
- -- but which, on simplification, don't actually need a dictionary involving
- -- the tyvar. So we have to do a proper simplification right here.
- tcSimplifyRank2 (mkTyVarSet sig_tyvars)
- lie_arg `thenTc` \ (free_insts, inst_binds) ->
+ tcSimplifyAndCheck
+ str
+ (mkTyVarSet zonked_sig_tyvars)
+ sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) ->
-- This HsLet binds any Insts which came out of the simplification.
-- It's a bit out of place here, but using AbsBind involves inventing
-- a couple of new names which seems worse.
- returnTc (TyLam sig_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts)
+ returnTc ( TyLam zonked_sig_tyvars $
+ DictLam dict_ids $
+ HsLet (MonoBind inst_binds [] Recursive)
+ arg'
+ , free_insts
)
- where
- mk_binds inst_binds = MonoBind inst_binds [] nonRecursive
\end{code}
%************************************************************************
case maybe_local of
Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id)
- Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
- tcInstType [] (idType id) `thenNF_Tc` \ inst_ty ->
+ Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
+ tcInstType emptyTyVarEnv (idType id) `thenNF_Tc` \ inst_ty ->
let
- (tyvars, rho) = splitForAllTy inst_ty
+ (tyvars, rho) = splitForAllTys inst_ty
in
instantiate_it2 (RealId id) tyvars rho
else
-- Yes, it's overloaded
newMethodWithGivenTy (OccurrenceOf tc_id_occ)
- tc_id_occ arg_tys rho `thenNF_Tc` \ (lie1, meth_id) ->
- instantiate_it meth_id tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
+ tc_id_occ arg_tys theta tau `thenNF_Tc` \ (lie1, meth_id) ->
+ instantiate_it meth_id tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
where
combine_stmts stmt _ (stmts, ty) = (stmt:stmts, ty)
in
tc_stmts stmts `thenTc` \ ((stmts', result_ty), final_lie) ->
- unifyTauTy result_ty res_ty `thenTc_`
+ unifyTauTy res_ty result_ty `thenTc_`
-- Build the then and zero methods in case we need them
-- It's important that "then" and "return" appear just once in the final LIE,
-> TcM s (thing, LIE s)
tcStmt tc_expr do_or_lc m combine stmt@(ReturnStmt exp) do_next
- = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True } )
+ = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True; Guard -> True } )
tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
tc_expr exp exp_ty `thenTc` \ (exp', exp_lie) ->
stmt_lie `plusLIE` thing_lie)
tcStmt tc_expr do_or_lc m combine stmt@(GuardStmt exp src_loc) do_next
- = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True } )
+ = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True; Guard -> True } )
newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
tcAddSrcLoc src_loc (
tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
stmt_lie `plusLIE` thing_lie)
tcStmt tc_expr do_or_lc m combine stmt@(ExprStmt exp src_loc) do_next
- = ASSERT( case do_or_lc of { DoStmt -> True; ListComp -> False } )
+ = ASSERT( case do_or_lc of { DoStmt -> True; ListComp -> False; Guard -> False } )
newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
tcAddSrcLoc src_loc (
tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
-- Record selectors all have type
-- forall a1..an. T a1 .. an -> tau
- ASSERT( maybeToBool (getFunTy_maybe tau) )
+ ASSERT( maybeToBool (splitFunTy_maybe tau) )
let
-- Selector must have type RecordType -> FieldType
- Just (record_ty, field_ty) = getFunTy_maybe tau
+ Just (record_ty, field_ty) = splitFunTy_maybe tau
in
unifyTauTy expected_record_ty record_ty `thenTc_`
- tcArg (rhs, field_ty) `thenTc` \ (rhs', lie) ->
+ tcPolyExpr (ptext SLIT("type of field") <+> quotes (ppr field_label))
+ rhs field_ty `thenTc` \ (rhs', lie) ->
returnTc ((RealId sel_id, rhs', pun_flag), lie)
badFields rbinds data_con
Mini-utils:
\begin{code}
-pp_nest_hang :: String -> Doc -> Doc
+pp_nest_hang :: String -> SDoc -> SDoc
pp_nest_hang label stuff = nest 2 (hang (text label) 4 stuff)
\end{code}
Boring and alphabetical:
\begin{code}
-arithSeqCtxt expr sty
- = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr sty expr)
+arithSeqCtxt expr
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-branchCtxt b1 b2 sty
- = sep [ptext SLIT("In the branches of a conditional:"),
- pp_nest_hang "`then' branch:" (ppr sty b1),
- pp_nest_hang "`else' branch:" (ppr sty b2)]
+caseCtxt expr
+ = hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
-caseCtxt expr sty
- = hang (ptext SLIT("In the case expression")) 4 (ppr sty expr)
+caseScrutCtxt expr
+ = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-exprSigCtxt expr sty
+exprSigCtxt expr
= hang (ptext SLIT("In an expression with a type signature:"))
- 4 (ppr sty expr)
+ 4 (ppr expr)
-listCtxt expr sty
- = hang (ptext SLIT("In the list element")) 4 (ppr sty expr)
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
-predCtxt expr sty
- = hang (ptext SLIT("In the predicate expression")) 4 (ppr sty expr)
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-sectionRAppCtxt expr sty
- = hang (ptext SLIT("In the right section")) 4 (ppr sty expr)
+sectionRAppCtxt expr
+ = hang (ptext SLIT("In the right section:")) 4 (ppr expr)
-sectionLAppCtxt expr sty
- = hang (ptext SLIT("In the left section")) 4 (ppr sty expr)
+sectionLAppCtxt expr
+ = hang (ptext SLIT("In the left section:")) 4 (ppr expr)
-funAppCtxt fun arg_no arg sty
+funAppCtxt fun arg arg_no
= hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
- ppr sty fun <> text ", namely"])
- 4 (ppr sty arg)
-
-stmtCtxt ListComp stmt sty
- = hang (ptext SLIT("In a pattern guard/list-comprehension qualifier:"))
- 4 (ppr sty stmt)
+ quotes (ppr fun) <> text ", namely"])
+ 4 (quotes (ppr arg))
-stmtCtxt DoStmt stmt sty
- = hang (ptext SLIT("In a do statement:"))
- 4 (ppr sty stmt)
+stmtCtxt do_or_lc stmt
+ = hang (ptext SLIT("In a") <+> whatever <> colon)
+ 4 (ppr stmt)
+ where
+ whatever = case do_or_lc of
+ ListComp -> ptext SLIT("list-comprehension qualifier")
+ DoStmt -> ptext SLIT("do statement")
+ Guard -> ptext SLIT("guard")
+
+wrongArgsCtxt too_many_or_few fun args
+ = hang (ptext SLIT("Probable cause:") <+> ppr fun
+ <+> ptext SLIT("is applied to") <+> text too_many_or_few
+ <+> ptext SLIT("arguments in the call"))
+ 4 (parens (ppr the_app))
+ where
+ the_app = foldl HsApp fun args -- Used in error messages
-tooManyArgsCtxt f sty
- = hang (ptext SLIT("Too many arguments in an application of the function"))
- 4 (ppr sty f)
+appCtxt fun args
+ = ptext SLIT("In the application") <+> (ppr the_app)
+ where
+ the_app = foldl HsApp fun args -- Used in error messages
-lurkingRank2Err fun fun_ty sty
- = hang (hsep [ptext SLIT("Illegal use of"), ppr sty fun])
- 4 (vcat [text "It is applied to too few arguments,",
- ptext SLIT("so that the result type has for-alls in it")])
+lurkingRank2Err fun fun_ty
+ = hang (hsep [ptext SLIT("Illegal use of"), quotes (ppr fun)])
+ 4 (vcat [ptext SLIT("It is applied to too few arguments"),
+ ptext SLIT("so that the result type has for-alls in it")])
-rank2ArgCtxt arg expected_arg_ty sty
- = hang (ptext SLIT("In a polymorphic function argument:"))
- 4 (sep [(<>) (ppr sty arg) (ptext SLIT(" ::")),
- ppr sty expected_arg_ty])
+rank2ArgCtxt arg expected_arg_ty
+ = ptext SLIT("In a polymorphic function argument:") <+> ppr arg
-badFieldsUpd rbinds sty
+badFieldsUpd rbinds
= hang (ptext SLIT("No constructor has all these fields:"))
- 4 (interpp'SP sty fields)
+ 4 (pprQuotedList fields)
where
fields = [field | (field, _, _) <- rbinds]
-recordUpdCtxt sty = ptext SLIT("In a record update construct")
+recordUpdCtxt = ptext SLIT("In a record update construct")
-badFieldsCon con fields sty
- = hsep [ptext SLIT("Constructor"), ppr sty con,
- ptext SLIT("does not have field(s)"), interpp'SP sty fields]
+badFieldsCon con fields
+ = hsep [ptext SLIT("Constructor"), ppr con,
+ ptext SLIT("does not have field(s):"), pprQuotedList fields]
-notSelector field sty
- = hsep [ppr sty field, ptext SLIT("is not a record selector")]
+notSelector field
+ = hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
\end{code}
projects / ghc-hetmet.git / blobdiff