\section[TcExpr]{Typecheck an expression}
\begin{code}
-#include "HsVersions.h"
-
-module TcExpr ( tcExpr, tcStmt, tcId ) where
+module TcExpr ( tcExpr, tcPolyExpr, 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 TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcStmt),
- TcIdOcc(..), SYN_IE(TcRecordBinds),
+import RnHsSyn ( RenamedHsExpr,
+ RenamedStmt, RenamedRecordBinds
+ )
+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, tcMatch )
+import TcMatches ( tcMatchesCase, tcMatchExpected )
+import TcGRHSs ( tcStmt )
import TcMonoType ( tcHsType )
-import TcPat ( tcPat )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( SYN_IE(TcType), TcMaybe(..),
- tcInstId, tcInstType, tcInstSigTcType, tcInstTyVars,
+import TcPat ( tcPat, badFieldsCon )
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( TcType, TcTauType, TcMaybe(..),
+ tcInstType, tcInstSigTcType, tcInstTyVars,
tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy,
- newTyVarTy, newTyVarTys, zonkTcTyVars, zonkTcType )
+ newTyVarTy, newTyVarTys, zonkTcType )
import TcKind ( TcKind )
-import Class ( SYN_IE(Class), classSig )
+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,
+ isForAllTy, 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}
+%************************************************************************
+%* *
+\subsection{Main wrappers}
+%* *
+%************************************************************************
+
+\begin{code}
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcType s -- Expected type (could be a polytpye)
+ -> TcM s (TcExpr s, LIE s)
+
+tcExpr expr ty | isForAllTy ty = -- Polymorphic case
+ tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) ->
+ returnTc (expr', lie)
+
+ | otherwise = -- Monomorphic case
+ tcMonoExpr expr ty
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{@tcPolyExpr@ typchecks an application}
+%* *
+%************************************************************************
+
\begin{code}
-tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)
+-- tcPolyExpr is like tcMonoExpr, except that the expected type
+-- can be a polymorphic one.
+tcPolyExpr :: RenamedHsExpr
+ -> TcType s -- Expected type
+ -> TcM s (TcExpr s, LIE s, -- Generalised expr with expected type, and LIE
+ TcExpr s, TcTauType s, LIE s) -- Same thing, but instantiated; tau-type returned
+
+tcPolyExpr arg expected_arg_ty
+ = -- Ha! The argument type of the function is a for-all type,
+ -- An example of rank-2 polymorphism.
+
+ -- To ensure that the forall'd type variables don't get unified with each
+ -- other or any other types, we make fresh copy of the alleged type
+ tcInstSigTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) ->
+ let
+ (sig_theta, sig_tau) = splitRhoTy sig_rho
+ in
+ -- Type-check the arg and unify with expected type
+ tcExtendGlobalTyVars sig_tyvars (
+ tcMonoExpr arg sig_tau
+ ) `thenTc` \ (arg', lie_arg) ->
+
+ -- Check that the arg_tyvars havn't been constrained
+ -- The interesting bit here is that we must include the free variables
+ -- of the expected arg ty. Here's an example:
+ -- runST (newVar True)
+ -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool))
+ -- for (newVar True), with s fresh. Then we unify with the runST's arg type
+ -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool.
+ -- So now s' isn't unconstrained because it's linked to a.
+ -- Conclusion: include the free vars of the expected arg type in the
+ -- list of "free vars" for the signature check.
+
+ 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
+
+ tcSimplifyAndCheck
+ (text "tcPolyExpr")
+ (mkTyVarSet zonked_sig_tyvars)
+ sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) ->
+
+ let
+ -- 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.
+ generalised_arg = TyLam zonked_sig_tyvars $
+ DictLam dict_ids $
+ HsLet (MonoBind inst_binds [] Recursive)
+ arg'
+ in
+ returnTc ( generalised_arg, free_insts,
+ arg', sig_tau, lie_arg )
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr (HsVar name)
- = tcId name `thenNF_Tc` \ (expr', lie, res_ty) ->
+tcMonoExpr :: RenamedHsExpr -- Expession to type check
+ -> TcTauType s -- Expected type (could be a type variable)
+ -> TcM s (TcExpr s, LIE s)
+
+tcMonoExpr (HsVar name) res_ty
+ = tcId name `thenNF_Tc` \ (expr', lie, id_ty) ->
+ 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
-- applied to something.
- checkTc (isTauTy res_ty)
- (lurkingRank2Err name res_ty) `thenTc_`
+ checkTc (isTauTy id_ty)
+ (lurkingRank2Err name id_ty) `thenTc_`
- returnTc (expr', lie, res_ty)
+ returnTc (expr', lie)
\end{code}
%************************************************************************
Overloaded literals.
\begin{code}
-tcExpr (HsLit (HsInt i))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
-
- newOverloadedLit (LiteralOrigin (HsInt i))
+tcMonoExpr (HsLit (HsInt i)) res_ty
+ = newOverloadedLit (LiteralOrigin (HsInt i))
(OverloadedIntegral i)
- ty `thenNF_Tc` \ (lie, over_lit_id) ->
-
- returnTc (HsVar over_lit_id, lie, ty)
-
-tcExpr (HsLit (HsFrac f))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
+ res_ty `thenNF_Tc` \ stuff ->
+ returnTc stuff
- newOverloadedLit (LiteralOrigin (HsFrac f))
+tcMonoExpr (HsLit (HsFrac f)) res_ty
+ = newOverloadedLit (LiteralOrigin (HsFrac f))
(OverloadedFractional f)
- ty `thenNF_Tc` \ (lie, over_lit_id) ->
+ res_ty `thenNF_Tc` \ stuff ->
+ returnTc stuff
- returnTc (HsVar over_lit_id, lie, ty)
-tcExpr (HsLit lit@(HsLitLit s))
+tcMonoExpr (HsLit lit@(HsLitLit s)) res_ty
= tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
newDicts (LitLitOrigin (_UNPK_ s))
- [(cCallableClass, ty)] `thenNF_Tc` \ (dicts, _) ->
- returnTc (HsLitOut lit ty, dicts, ty)
+ [(cCallableClass, [res_ty])] `thenNF_Tc` \ (dicts, _) ->
+ returnTc (HsLitOut lit res_ty, dicts)
\end{code}
Primitive literals:
\begin{code}
-tcExpr (HsLit lit@(HsCharPrim c))
- = returnTc (HsLitOut lit charPrimTy, emptyLIE, charPrimTy)
+tcMonoExpr (HsLit lit@(HsCharPrim c)) res_ty
+ = unifyTauTy res_ty charPrimTy `thenTc_`
+ returnTc (HsLitOut lit charPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsStringPrim s))
- = returnTc (HsLitOut lit addrPrimTy, emptyLIE, addrPrimTy)
+tcMonoExpr (HsLit lit@(HsStringPrim s)) res_ty
+ = unifyTauTy res_ty addrPrimTy `thenTc_`
+ returnTc (HsLitOut lit addrPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsIntPrim i))
- = returnTc (HsLitOut lit intPrimTy, emptyLIE, intPrimTy)
+tcMonoExpr (HsLit lit@(HsIntPrim i)) res_ty
+ = unifyTauTy res_ty intPrimTy `thenTc_`
+ returnTc (HsLitOut lit intPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsFloatPrim f))
- = returnTc (HsLitOut lit floatPrimTy, emptyLIE, floatPrimTy)
+tcMonoExpr (HsLit lit@(HsFloatPrim f)) res_ty
+ = unifyTauTy res_ty floatPrimTy `thenTc_`
+ returnTc (HsLitOut lit floatPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsDoublePrim d))
- = returnTc (HsLitOut lit doublePrimTy, emptyLIE, doublePrimTy)
+tcMonoExpr (HsLit lit@(HsDoublePrim d)) res_ty
+ = unifyTauTy res_ty doublePrimTy `thenTc_`
+ returnTc (HsLitOut lit doublePrimTy, emptyLIE)
\end{code}
Unoverloaded literals:
\begin{code}
-tcExpr (HsLit lit@(HsChar c))
- = returnTc (HsLitOut lit charTy, emptyLIE, charTy)
+tcMonoExpr (HsLit lit@(HsChar c)) res_ty
+ = unifyTauTy res_ty charTy `thenTc_`
+ returnTc (HsLitOut lit charTy, emptyLIE)
-tcExpr (HsLit lit@(HsString str))
- = returnTc (HsLitOut lit stringTy, emptyLIE, stringTy)
+tcMonoExpr (HsLit lit@(HsString str)) res_ty
+ = unifyTauTy res_ty stringTy `thenTc_`
+ returnTc (HsLitOut lit stringTy, emptyLIE)
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr (HsPar expr) -- preserve parens so printing needn't guess where they go
- = tcExpr expr
+tcMonoExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go
+ = tcMonoExpr expr res_ty
-tcExpr (NegApp expr neg) = tcExpr (HsApp neg expr)
+-- 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 (HsLam match)
- = tcMatch match `thenTc` \ (match',lie,ty) ->
- returnTc (HsLam match', lie, ty)
+tcMonoExpr (NegApp (HsLit (HsInt i)) neg) res_ty
+ = tcMonoExpr (HsLit (HsInt (-i))) res_ty
-tcExpr (HsApp e1 e2) = accum e1 [e2]
+tcMonoExpr (NegApp expr neg) res_ty
+ = tcMonoExpr (HsApp neg expr) res_ty
+
+tcMonoExpr (HsLam match) res_ty
+ = tcMatchExpected [] res_ty match `thenTc` \ (match',lie) ->
+ returnTc (HsLam match', lie)
+
+tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2]
where
accum (HsApp e1 e2) args = accum e1 (e2:args)
accum fun args
- = tcApp fun args `thenTc` \ (fun', args', lie, res_ty) ->
- returnTc (foldl HsApp fun' args', lie, res_ty)
+ = tcApp fun args res_ty `thenTc` \ (fun', args', lie) ->
+ returnTc (foldl HsApp fun' args', lie)
-- equivalent to (op e1) e2:
-tcExpr (OpApp arg1 op fix arg2)
- = tcApp op [arg1,arg2] `thenTc` \ (op', [arg1', arg2'], lie, res_ty) ->
- returnTc (OpApp arg1' op' fix arg2', lie, res_ty)
+tcMonoExpr (OpApp arg1 op fix arg2) res_ty
+ = tcApp op [arg1,arg2] res_ty `thenTc` \ (op', [arg1', arg2'], lie) ->
+ returnTc (OpApp arg1' op' fix arg2', lie)
\end{code}
Note that the operators in sections are expected to be binary, and
-- or just
-- op e
-tcExpr in_expr@(SectionL arg op)
- = tcApp op [arg] `thenTc` \ (op', [arg'], lie, res_ty) ->
+tcMonoExpr in_expr@(SectionL arg op) res_ty
+ = tcApp op [arg] res_ty `thenTc` \ (op', [arg'], lie) ->
-- Check that res_ty is a function type
-- Without this check we barf in the desugarer on
-- because it tries to desugar to
-- f op = \r -> 3 op r
-- so (3 `op`) had better be a function!
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
tcAddErrCtxt (sectionLAppCtxt in_expr) $
- unifyTauTy (mkFunTy ty1 ty2) res_ty `thenTc_`
+ unifyFunTy res_ty `thenTc_`
- returnTc (SectionL arg' op', lie, res_ty)
+ returnTc (SectionL arg' op', lie)
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcExpr in_expr@(SectionR op expr)
- = tcExpr op `thenTc` \ (op', lie1, op_ty) ->
- tcExpr expr `thenTc` \ (expr',lie2, expr_ty) ->
-
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
+tcMonoExpr in_expr@(SectionR op expr) res_ty
+ = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
tcAddErrCtxt (sectionRAppCtxt in_expr) $
- unifyTauTy (mkFunTys [ty1, expr_ty] ty2) op_ty `thenTc_`
-
- returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2)
+ split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcMonoExpr expr arg2_ty `thenTc` \ (expr',lie2) ->
+ unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_`
+ returnTc (SectionR op' expr', lie1 `plusLIE` lie2)
\end{code}
The interesting thing about @ccall@ is that it is just a template
later use.
\begin{code}
-tcExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty)
+tcMonoExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty
= -- 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 -}
in
-- Arguments
- tcExprs args `thenTc` \ (args', args_lie, arg_tys) ->
+ mapNF_Tc (\ _ -> newTyVarTy mkTypeKind) [1..(length args)] `thenNF_Tc` \ ty_vars ->
+ tcMonoExprs 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 ->
+ let
+ io_result_ty = mkTyConApp ioTyCon [result_ty]
+ in
+ 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 arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) ->
+ mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args ty_vars) `thenNF_Tc` \ ccarg_dicts_s ->
+ 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),
+ case tyConDataCons ioTyCon of { [ioDataCon] ->
+ 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,
- mkPrimIoTy result_ty)
+ foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie)
+ }
\end{code}
\begin{code}
-tcExpr (HsSCC label expr)
- = tcExpr expr `thenTc` \ (expr', lie, expr_ty) ->
- -- No unification. Give SCC the type of expr
- returnTc (HsSCC label expr', lie, expr_ty)
+tcMonoExpr (HsSCC label expr) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (HsSCC label expr', lie)
-tcExpr (HsLet binds expr)
+tcMonoExpr (HsLet binds expr) res_ty
= tcBindsAndThen
combiner
binds -- Bindings to check
- (tc_expr expr) `thenTc` \ ((expr', ty), lie) ->
- returnTc (expr', lie, ty)
+ tc_expr `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
where
- tc_expr expr = tcExpr expr `thenTc` \ (expr', lie, ty) ->
- returnTc ((expr',ty), lie)
- combiner bind (expr, ty) = (HsLet bind expr, ty)
-
-tcExpr in_expr@(HsCase expr matches src_loc)
- = tcAddSrcLoc src_loc $
- tcExpr expr `thenTc` \ (expr',lie1,expr_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ result_ty ->
+ tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
+ combiner is_rec bind expr = HsLet (MonoBind bind [] is_rec) expr
- tcAddErrCtxt (caseCtxt in_expr) $
- tcMatchesCase (mkFunTy expr_ty result_ty) matches
- `thenTc` \ (matches',lie2) ->
+tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (caseCtxt in_expr) $
- returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2, result_ty)
+ -- 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
-tcExpr (HsIf pred b1 b2 src_loc)
- = tcAddSrcLoc src_loc $
- tcExpr pred `thenTc` \ (pred',lie1,predTy) ->
+ tcMatchesCase res_ty matches `thenTc` \ (scrut_ty, matches', lie2) ->
- tcAddErrCtxt (predCtxt pred) (
- unifyTauTy boolTy predTy
- ) `thenTc_`
+ tcAddErrCtxt (caseScrutCtxt scrut) (
+ tcMonoExpr scrut scrut_ty
+ ) `thenTc` \ (scrut',lie1) ->
- tcExpr b1 `thenTc` \ (b1',lie2,result_ty) ->
- tcExpr b2 `thenTc` \ (b2',lie3,b2Ty) ->
+ returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
- tcAddErrCtxt (branchCtxt b1 b2) $
- unifyTauTy result_ty b2Ty `thenTc_`
+tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (predCtxt pred) (
+ tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
- returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty)
+ 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}
\begin{code}
-tcExpr expr@(HsDo do_or_lc stmts src_loc)
- = tcDoStmts do_or_lc stmts src_loc
+tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty
+ = tcDoStmts do_or_lc stmts src_loc res_ty
\end{code}
\begin{code}
-tcExpr (ExplicitList [])
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty)
-
-
-tcExpr in_expr@(ExplicitList exprs) -- Non-empty list
- = tcExprs exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) ->
- tcAddErrCtxt (listCtxt in_expr) $
- unifyTauTyList tys `thenTc_`
- returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty)
-
-tcExpr (ExplicitTuple exprs)
- = tcExprs exprs `thenTc` \ (exprs', lie, tys) ->
- returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys)
-
-tcExpr (RecordCon (HsVar con) rbinds)
- = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+tcMonoExpr in_expr@(ExplicitList exprs) res_ty -- Non-empty list
+ = unifyListTy res_ty `thenTc` \ elt_ty ->
+ mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) ->
+ returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies)
+ where
+ tc_elt elt_ty expr
+ = tcAddErrCtxt (listCtxt expr) $
+ tcMonoExpr expr elt_ty
+
+tcMonoExpr (ExplicitTuple exprs) res_ty
+ = unifyTupleTy (length exprs) res_ty `thenTc` \ arg_tys ->
+ mapAndUnzipTc (\ (expr, arg_ty) -> tcMonoExpr expr arg_ty)
+ (exprs `zip` arg_tys) -- we know they're of equal length.
+ `thenTc` \ (exprs', lies) ->
+ returnTc (ExplicitTuple exprs', plusLIEs lies)
+
+tcMonoExpr (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 ) )
+ 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_name 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, record_ty)
+ returnTc (RecordCon (RealId con_id) con_expr rbinds', con_lie `plusLIE` rbinds_lie)
-- The main complication with RecordUpd is that we need to explicitly
--
-- All this is done in STEP 4 below.
-tcExpr (RecordUpd record_expr rbinds)
+tcMonoExpr (RecordUpd record_expr rbinds) res_ty
= tcAddErrCtxt recordUpdCtxt $
-- STEP 1
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 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
- tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
- unifyTauTy (applyTyCon tycon inst_tys) record_ty `thenTc_`
-
+ let
+ record_ty = mkTyConApp tycon inst_tys
+ in
+ tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
-- STEP 6
-- Figure out the LIE we need. We have to generate some
-- 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) ->
-- Phew!
returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds',
- con_lie `plusLIE` record_lie `plusLIE` rbinds_lie,
- result_record_ty)
+ con_lie `plusLIE` record_lie `plusLIE` rbinds_lie)
-
-tcExpr (ArithSeqIn seq@(From expr))
- = tcExpr expr `thenTc` \ (expr', lie1, ty) ->
+tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
+ = unifyListTy res_ty `thenTc` \ elt_ty ->
+ tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) ->
tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
+ (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'),
- lie1 `plusLIE` lie2,
- mkListTy ty)
-
-tcExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
-
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1, ty2] `thenTc_`
+ lie1 `plusLIE` lie2)
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+ = tcAddErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenTc` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
+ (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
returnTc (ArithSeqOut (HsVar enum_from_then_id)
(FromThen expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3,
- mkListTy ty1)
-
-tcExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
-
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1,ty2] `thenTc_`
+ lie1 `plusLIE` lie2 `plusLIE` lie3)
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = tcAddErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenTc` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
+ (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
returnTc (ArithSeqOut (HsVar enum_from_to_id)
(FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3,
- mkListTy ty1)
-
-tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
- tcExpr expr3 `thenTc` \ (expr3',lie3,ty3) ->
-
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1,ty2,ty3] `thenTc_`
-
+ lie1 `plusLIE` lie2 `plusLIE` lie3)
+
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = tcAddErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenTc` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+ tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie4, eft_id) ->
+ (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie4, eft_id) ->
returnTc (ArithSeqOut (HsVar eft_id)
(FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4,
- mkListTy ty1)
+ lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4)
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr in_expr@(ExprWithTySig expr poly_ty)
- = tcExpr expr `thenTc` \ (texpr, lie, tau_ty) ->
- tcHsType poly_ty `thenTc` \ sigma_sig ->
-
- -- Check the tau-type part
- tcSetErrCtxt (exprSigCtxt in_expr) $
- tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' ->
- let
- (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
- in
- unifyTauTy sig_tau' tau_ty `thenTc_`
-
- -- Check the type variables of the signature
- checkSigTyVars sig_tyvars' sig_tau' `thenTc_`
-
- -- Check overloading constraints
- newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) ->
- tcSimplifyAndCheck
- (mkTyVarSet sig_tyvars')
- sig_dicts lie `thenTc_`
-
- -- If everything is ok, return the stuff unchanged, except for
- -- the effect of any substutions etc. We simply discard the
- -- result of the tcSimplifyAndCheck, except for any default
- -- resolution it may have done, which is recorded in the
- -- substitution.
- returnTc (texpr, lie, tau_ty)
+tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = tcSetErrCtxt (exprSigCtxt in_expr) $
+ tcHsType poly_ty `thenTc` \ sig_ty ->
+ tcInstSigType sig_ty `thenNF_Tc` \ sig_tc_ty ->
+
+ if not (isForAllTy sig_tc_ty) then
+ -- Easy case
+ unifyTauTy sig_tc_ty res_ty `thenTc_`
+ tcMonoExpr expr sig_tc_ty
+
+ else -- Signature is polymorphic
+ tcPolyExpr expr sig_tc_ty `thenTc` \ (_, _, expr, expr_ty, lie) ->
+
+ -- 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 expr_ty `thenTc_`
+
+ -- If everything is ok, return the stuff unchanged, except for
+ -- the effect of any substutions etc. We simply discard the
+ -- result of the tcSimplifyAndCheck (inside tcPolyExpr), except for any default
+ -- resolution it may have done, which is recorded in the
+ -- substitution.
+ returnTc (expr, lie)
+\end{code}
+
+Typecheck expression which in most cases will be an Id.
+
+\begin{code}
+tcExpr_id :: RenamedHsExpr
+ -> TcM s (TcExpr s,
+ LIE s,
+ TcType s)
+tcExpr_id id_expr
+ = case id_expr of
+ HsVar name -> tcId name `thenNF_Tc` \ stuff ->
+ returnTc stuff
+ other -> newTyVarTy mkTypeKind `thenNF_Tc` \ id_ty ->
+ tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
+ returnTc (id_expr', lie_id, id_ty)
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
+
tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
+ -> TcType s -- Expected result type of application
-> TcM s (TcExpr s, [TcExpr s], -- Translated fun and args
- LIE s,
- TcType s) -- Type of the application
+ LIE s)
-tcApp fun args
+tcApp fun args res_ty
= -- First type-check the function
- -- In the HsVar case we go straight to tcId to avoid hitting the
- -- rank-2 check, which we check later here anyway
- (case fun of
- HsVar name -> tcId name `thenNF_Tc` \ stuff -> returnTc stuff
- other -> tcExpr fun
- ) `thenTc` \ (fun', lie_fun, fun_ty) ->
+ tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) ->
- tcApp_help fun 1 fun_ty args `thenTc` \ (args', lie_args, res_ty) ->
+ tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
+ split_fun_ty fun_ty (length args)
+ ) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
- -- 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 res_ty)
- (lurkingRank2Err fun fun_ty) `thenTc_`
+ -- Unify with expected result before type-checking the args
+ -- 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_`
- returnTc (fun', args', lie_fun `plusLIE` lie_args, res_ty)
+ -- Now typecheck the args
+ 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_`
-tcApp_help :: RenamedHsExpr -> Int -- Function and arg position, used in error message(s)
- -> TcType s -- The type of the function
- -> [RenamedHsExpr] -- Arguments
- -> TcM s ([TcExpr s], -- Typechecked args
- LIE s,
- TcType s) -- Result type of the application
+ returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s)
-tcApp_help orig_fun arg_no fun_ty []
- = returnTc ([], emptyLIE, fun_ty)
-tcApp_help orig_fun arg_no fun_ty all_args@(arg:args)
- = -- Expect the function to have type A->B
- tcAddErrCtxt (tooManyArgsCtxt orig_fun) (
- unifyFunTy fun_ty
- ) `thenTc` \ (expected_arg_ty, result_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
+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
- -- Type check the argument
- tcAddErrCtxt (funAppCtxt orig_fun arg_no arg) (
- tcArg expected_arg_ty arg
- ) `thenTc` \ (arg', lie_arg) ->
- -- Do the other args
- tcApp_help orig_fun (arg_no+1) result_ty args `thenTc` \ (args', lie_args, res_ty) ->
+split_fun_ty :: TcType s -- The type of the function
+ -> Int -- Number of arguments
+ -> TcM s ([TcType s], -- Function argument types
+ TcType s) -- Function result types
- -- Done
- returnTc (arg':args', lie_arg `plusLIE` lie_args, res_ty)
+split_fun_ty fun_ty 0
+ = returnTc ([], fun_ty)
+split_fun_ty fun_ty n
+ = -- Expect the function to have type A->B
+ unifyFunTy fun_ty `thenTc` \ (arg_ty, res_ty) ->
+ split_fun_ty res_ty (n-1) `thenTc` \ (arg_tys, final_res_ty) ->
+ returnTc (arg_ty:arg_tys, final_res_ty)
\end{code}
\begin{code}
-tcArg :: TcType s -- Expected arg type
- -> RenamedHsExpr -- Actual argument
+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 expected_arg_ty arg
- | not (maybeToBool (getForAllTy_maybe expected_arg_ty))
- = -- The ordinary, non-rank-2 polymorphic case
- tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy expected_arg_ty actual_arg_ty `thenTc_`
- returnTc (arg', lie_arg)
-
- | otherwise
- = -- Ha! The argument type of the function is a for-all type,
- -- An example of rank-2 polymorphism.
-
- -- No need to instantiate the argument type... it's must be the result
- -- of instantiating a function involving rank-2 polymorphism, so there
- -- isn't any danger of using the same tyvars twice
- -- The argument type shouldn't be overloaded type (hence ASSERT)
-
- -- To ensure that the forall'd type variables don't get unified with each
- -- other or any other types, we make fresh *signature* type variables
- -- and unify them with the tyvars.
- tcInstSigTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) ->
- 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 `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy sig_tau actual_arg_ty `thenTc_`
-
- -- Check that the arg_tyvars havn't been constrained
- -- The interesting bit here is that we must include the free variables
- -- of the expected arg ty. Here's an example:
- -- runST (newVar True)
- -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool))
- -- for (newVar True), with s fresh. Then we unify with the runST's arg type
- -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool.
- -- So now s' isn't unconstrained because it's linked to a.
- -- 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_`
-
- -- 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) ->
-
- -- 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)
- )
- where
- mk_binds inst_binds = MonoBind inst_binds [] nonRecursive
+tcArg the_fun (arg, expected_arg_ty, arg_no)
+ = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
+ tcExpr arg expected_arg_ty
\end{code}
+
%************************************************************************
%* *
\subsection{@tcId@ typchecks an identifier occurrence}
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
%************************************************************************
\begin{code}
-tcDoStmts do_or_lc stmts src_loc
+tcDoStmts do_or_lc stmts src_loc res_ty
= -- get the Monad and MonadZero classes
-- create type consisting of a fresh monad tyvar
ASSERT( not (null stmts) )
let
tc_stmts [] = returnTc (([], error "tc_stmts"), emptyLIE)
- tc_stmts (stmt:stmts) = tcStmt tcExpr do_or_lc (mkAppTy m) combine_stmts stmt $
+ tc_stmts (stmt:stmts) = tcStmt do_or_lc (mkAppTy m) combine_stmts stmt $
tc_stmts stmts
combine_stmts stmt@(ReturnStmt _) (Just ty) ([], _) = ([stmt], ty)
combine_stmts stmt _ ([], _) = panic "Bad last stmt tcDoStmts"
combine_stmts stmt _ (stmts, ty) = (stmt:stmts, ty)
in
- tc_stmts stmts `thenTc` \ ((stmts', result_ty), final_lie) ->
+ tc_stmts stmts `thenTc` \ ((stmts', result_ty), final_lie) ->
+ 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,
failure_free (GuardStmt _ _) = False
failure_free other_stmt = True
in
- returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id result_ty src_loc,
- final_lie `plusLIE` monad_lie,
- result_ty)
-\end{code}
+ returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id res_ty src_loc,
+ final_lie `plusLIE` monad_lie)
-\begin{code}
-tcStmt :: (RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)) -- This is tcExpr
- -- The sole, disgusting, reason for this parameter
- -- is to get the effect of polymorphic recursion
- -- ToDo: rm when booting with Haskell 1.3
- -> DoOrListComp
- -> (TcType s -> TcType s) -- Relationship type of pat and rhs in pat <- rhs
- -> (TcStmt s -> Maybe (TcType s) -> thing -> thing)
- -> RenamedStmt
- -> TcM s (thing, LIE s)
- -> 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 } )
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- returnTc (ReturnStmt exp', exp_lie, m exp_ty)
- ) `thenTc` \ (stmt', stmt_lie, stmt_ty) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' (Just stmt_ty) thing',
- 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 } )
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- unifyTauTy boolTy exp_ty `thenTc_`
- returnTc (GuardStmt exp' src_loc, exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' Nothing thing',
- 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 } )
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- -- Check that exp has type (m tau) for some tau (doesn't matter what)
- newTyVarTy mkTypeKind `thenNF_Tc` \ tau ->
- unifyTauTy (m tau) exp_ty `thenTc_`
- returnTc (ExprStmt exp' src_loc, exp_lie, exp_ty)
- )) `thenTc` \ (stmt', stmt_lie, stmt_ty) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' (Just stmt_ty) thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine stmt@(BindStmt pat exp src_loc) do_next
- = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) ->
- tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- unifyTauTy (m pat_ty) exp_ty `thenTc_`
-
- -- NB: the environment has been extended with the new binders
- -- which the rhs can't "see", but the renamer should have made
- -- sure that everything is distinct by now, so there's no problem.
- -- Putting the tcExpr before the newMonoIds messes up the nesting
- -- of error contexts, so I didn't bother
-
- returnTc (BindStmt pat' exp' src_loc, pat_lie `plusLIE` exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' Nothing thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine (LetStmt binds) do_next
- = tcBindsAndThen -- No error context, but a binding group is
- combine' -- rather a large thing for an error context anyway
- binds
- do_next
- where
- combine' binds' thing' = combine (LetStmt binds') Nothing thing'
\end{code}
+
%************************************************************************
%* *
\subsection{Record bindings}
-- 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 field_ty rhs `thenTc` \ (rhs', lie) ->
+ tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) ->
returnTc ((RealId sel_id, rhs', pun_flag), lie)
badFields rbinds data_con
%************************************************************************
%* *
-\subsection{@tcExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions}
%* *
%************************************************************************
\begin{code}
-tcExprs :: [RenamedHsExpr] -> TcM s ([TcExpr s], LIE s, [TcType s])
+tcMonoExprs :: [RenamedHsExpr] -> [TcType s] -> TcM s ([TcExpr s], LIE s)
-tcExprs [] = returnTc ([], emptyLIE, [])
-tcExprs (expr:exprs)
- = tcExpr expr `thenTc` \ (expr', lie1, ty) ->
- tcExprs exprs `thenTc` \ (exprs', lie2, tys) ->
- returnTc (expr':exprs', lie1 `plusLIE` lie2, ty:tys)
+tcMonoExprs [] [] = returnTc ([], emptyLIE)
+tcMonoExprs (expr:exprs) (ty:tys)
+ = tcMonoExpr expr ty `thenTc` \ (expr', lie1) ->
+ tcMonoExprs exprs tys `thenTc` \ (exprs', lie2) ->
+ returnTc (expr':exprs', lie1 `plusLIE` lie2)
\end{code}
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 a 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 a list expression:")) 4 (ppr sty expr)
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
-predCtxt expr sty
- = hang (ptext SLIT("In a 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 a 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 a 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 (pprParendExpr sty arg)
-
-stmtCtxt ListComp stmt sty
- = hang (ptext SLIT("In a list-comprehension qualifer:"))
- 4 (ppr sty stmt)
-
-stmtCtxt DoStmt stmt sty
- = hang (ptext SLIT("In a do statement:"))
- 4 (ppr sty stmt)
+ quotes (ppr fun) <> text ", namely"])
+ 4 (quotes (ppr arg))
+
+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")
-
-badFieldsCon con fields sty
- = hsep [ptext SLIT("Constructor"), ppr sty con,
- ptext SLIT("does not have field(s)"), interpp'SP sty fields]
+recordUpdCtxt = ptext SLIT("In a record update construct")
-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