%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcExpr]{Typecheck an expression}
\begin{code}
-#include "HsVersions.h"
-
-module TcExpr ( tcExpr ) where
+module TcExpr ( tcApp, tcExpr, tcPolyExpr, tcId ) where
-import Ubiq
+#include "HsVersions.h"
-import HsSyn ( HsExpr(..), Qual(..), Stmt(..),
- HsBinds(..), Bind(..), MonoBinds(..),
- ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds,
- Match, Fake, InPat, OutPat, PolyType,
- irrefutablePat, collectPatBinders )
-import RnHsSyn ( RenamedHsExpr(..), RenamedQual(..),
- RenamedStmt(..), RenamedRecordBinds(..),
- RnName{-instance Outputable-}
+import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
+ HsBinds(..), MonoBinds(..), Stmt(..), StmtCtxt(..),
+ mkMonoBind, nullMonoBinds
)
-import TcHsSyn ( TcExpr(..), TcQual(..), TcStmt(..),
- TcIdOcc(..), TcRecordBinds(..),
- mkHsTyApp
+import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
+import TcHsSyn ( TcExpr, TcRecordBinds, mkHsConApp,
+ mkHsTyApp, mkHsLet
)
-import TcMonad hiding ( rnMtoTcM )
+import TcMonad
+import BasicTypes ( RecFlag(..) )
+
import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- LIE(..), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
- newMethod, newMethodWithGivenTy, newDicts )
+ LIE, emptyLIE, unitLIE, consLIE, plusLIE, plusLIEs,
+ lieToList, listToLIE,
+ newOverloadedLit, newMethod, newIPDict,
+ instOverloadedFun, newDicts, newClassDicts,
+ getIPsOfLIE, instToId, ipToId
+ )
import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
- tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars
+import TcEnv ( tcInstId,
+ tcLookupValue, tcLookupClassByKey,
+ tcLookupValueByKey,
+ tcExtendGlobalTyVars, tcLookupValueMaybe,
+ tcLookupTyCon, tcLookupDataCon
+ )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts )
+import TcMonoType ( tcHsSigType, checkSigTyVars, sigCtxt )
+import TcPat ( badFieldCon )
+import TcSimplify ( tcSimplify, tcSimplifyAndCheck, partitionPredsOfLIE )
+import TcType ( TcType, TcTauType,
+ tcInstTyVars,
+ tcInstTcType, tcSplitRhoTy,
+ newTyVarTy, newTyVarTy_OpenKind, zonkTcType )
+
+import Class ( Class )
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType
+ )
+import Id ( idType, recordSelectorFieldLabel,
+ isRecordSelector,
+ Id, mkVanillaId
)
-import TcMatches ( tcMatchesCase, tcMatch )
-import TcMonoType ( tcPolyType )
-import TcPat ( tcPat )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( TcType(..), TcMaybe(..),
- tcInstId, tcInstType, tcInstTheta, tcInstTyVars,
- newTyVarTy, zonkTcTyVars, zonkTcType )
-import TcKind ( TcKind )
-
-import Class ( Class(..), classSig )
-import FieldLabel ( fieldLabelName )
-import Id ( Id(..), GenId, idType, dataConFieldLabels, dataConSig )
-import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
-import GenSpecEtc ( checkSigTyVars, checkSigTyVarsGivenGlobals )
-import Name ( Name{-instance Eq-} )
+import DataCon ( dataConFieldLabels, dataConSig,
+ dataConStrictMarks, StrictnessMark(..)
+ )
+import Name ( Name, getName )
import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys,
- getTyVar_maybe, getFunTy_maybe, instantiateTy,
- splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy,
- isTauTy, mkFunTys, tyVarsOfType, getForAllTy_maybe,
- getAppDataTyCon, maybeAppDataTyCon
+ ipName_maybe,
+ splitFunTy_maybe, splitFunTys, isNotUsgTy,
+ mkTyConApp,
+ splitForAllTys, splitRhoTy,
+ isTauTy, tyVarsOfType, tyVarsOfTypes,
+ isForAllTy, splitAlgTyConApp, splitAlgTyConApp_maybe,
+ boxedTypeKind, mkArrowKind,
+ tidyOpenType
)
-import TyVar ( GenTyVar, TyVarSet(..), unionTyVarSets, mkTyVarSet )
+import Subst ( mkTopTyVarSubst, substClasses )
+import UsageSPUtils ( unannotTy )
+import VarSet ( emptyVarSet, unionVarSet, elemVarSet, mkVarSet )
+import TyCon ( tyConDataCons )
import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
floatPrimTy, addrPrimTy
)
-import TysWiredIn ( addrTy,
- boolTy, charTy, stringTy, mkListTy,
- mkTupleTy, mkPrimIoTy
- )
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
+import TysWiredIn ( boolTy, charTy, stringTy )
+import PrelInfo ( ioTyCon_NAME )
+import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy,
+ unifyUnboxedTupleTy )
+import Unique ( cCallableClassKey, cReturnableClassKey,
enumFromClassOpKey, enumFromThenClassOpKey,
enumFromToClassOpKey, enumFromThenToClassOpKey,
- monadClassKey, monadZeroClassKey
+ thenMClassOpKey, failMClassOpKey, returnMClassOpKey
)
---import Name ( Name ) -- Instance
-import Outputable ( interpp'SP )
-import PprType ( GenType, GenTyVar ) -- Instances
-import Maybes ( maybeToBool )
-import Pretty
+import Outputable
+import Maybes ( maybeToBool, mapMaybe )
+import ListSetOps ( minusList )
import Util
+import CmdLineOpts ( opt_WarnMissingFields )
+
\end{code}
+%************************************************************************
+%* *
+\subsection{Main wrappers}
+%* *
+%************************************************************************
+
\begin{code}
-tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcType -- Expected type (could be a polytpye)
+ -> TcM s (TcExpr, LIE)
+
+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}
+-- tcPolyExpr is like tcMonoExpr, except that the expected type
+-- can be a polymorphic one.
+tcPolyExpr :: RenamedHsExpr
+ -> TcType -- Expected type
+ -> TcM s (TcExpr, LIE, -- Generalised expr with expected type, and LIE
+ TcExpr, TcTauType, LIE) -- 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
+ tcInstTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) ->
+ let
+ (sig_theta, sig_tau) = splitRhoTy sig_rho
+ free_tyvars = tyVarsOfType expected_arg_ty
+ in
+ -- Type-check the arg and unify with expected type
+ tcMonoExpr arg sig_tau `thenTc` \ (arg', lie_arg) ->
+
+ -- Check that the sig_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 free_tyvars $
+ tcAddErrCtxtM (sigCtxt sig_msg sig_tyvars sig_theta sig_tau) $
+
+ checkSigTyVars sig_tyvars free_tyvars `thenTc` \ zonked_sig_tyvars ->
+
+ newDicts SignatureOrigin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) ->
+ -- ToDo: better origin
+ tcSimplifyAndCheck
+ (text "the type signature of an expression")
+ (mkVarSet 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 $
+ mkHsLet inst_binds $
+ arg'
+ in
+ returnTc ( generalised_arg, free_insts,
+ arg', sig_tau, lie_arg )
+ where
+ sig_msg = ptext SLIT("When checking an expression type signature")
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr (HsVar name)
- = tcId name `thenNF_Tc` \ (expr', lie, res_ty) ->
+tcMonoExpr :: RenamedHsExpr -- Expession to type check
+ -> TcTauType -- Expected type (could be a type variable)
+ -> TcM s (TcExpr, LIE)
+
+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)
+\end{code}
- returnTc (expr', lie, res_ty)
+\begin{code}
+tcMonoExpr (HsIPVar name) res_ty
+ -- ZZ What's the `id' used for here...
+ = let id = mkVanillaId name res_ty in
+ tcGetInstLoc (OccurrenceOf id) `thenNF_Tc` \ loc ->
+ newIPDict name res_ty loc `thenNF_Tc` \ ip ->
+ returnNF_Tc (HsIPVar (instToId ip), unitLIE ip)
\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)
+ newClassDicts (LitLitOrigin (_UNPK_ s))
+ [(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
+ = tcMatchLambda match res_ty `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 arg2)
- = tcApp op [arg1,arg2] `thenTc` \ (op', [arg1', arg2'], lie, res_ty) ->
- returnTc (OpApp arg1' op' 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 op_ty (mkFunTys [ty1, expr_ty] ty2) `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 (HsCCall 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 `thenNF_Tc` \ ioTyCon ->
let
new_arg_dict (arg, arg_ty)
- = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
- [(cCallableClass, arg_ty)] `thenNF_Tc` \ (arg_dicts, _) ->
+ = newClassDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
+ [(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) ->
+ let n_args = length args
+ tv_idxs | n_args == 0 = []
+ | otherwise = [1..n_args]
+ in
+ mapNF_Tc (\ _ -> newTyVarTy_OpenKind) tv_idxs `thenNF_Tc` \ arg_tys ->
+ tcMonoExprs args arg_tys `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 ->
+ newTyVarTy boxedTypeKind `thenNF_Tc` \ result_ty ->
+ let
+ io_result_ty = mkTyConApp ioTyCon [result_ty]
+ [ioDataCon] = tyConDataCons ioTyCon
+ 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, _) ->
-
- returnTc (CCall lbl args' may_gc is_asm result_ty,
- foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie,
- mkPrimIoTy result_ty)
+ mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
+ newClassDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
+ returnTc (HsCCall lbl args' may_gc is_asm io_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 lbl expr) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (HsSCC lbl expr', lie)
-tcExpr (HsLet binds expr)
+tcMonoExpr (HsLet binds expr) res_ty
= tcBindsAndThen
- HsLet -- The combiner
+ combiner
binds -- Bindings to check
- (tcExpr expr) -- Typechecker for the expression
-
-tcExpr in_expr@(HsCase expr matches src_loc)
- = tcAddSrcLoc src_loc $
- tcExpr expr `thenTc` \ (expr',lie1,expr_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ result_ty ->
-
- tcAddErrCtxt (caseCtxt in_expr) $
- tcMatchesCase (mkFunTy expr_ty result_ty) matches
- `thenTc` \ (matches',lie2) ->
-
- returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2, result_ty)
-
-tcExpr (HsIf pred b1 b2 src_loc)
+ tc_expr `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
+ where
+ tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
+ combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr
+
+tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (caseCtxt in_expr) $
+
+ -- 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
+ --
+ -- Not only that, but it's better to check the matches on their
+ -- own, so that we get the expected results for scoped type variables.
+ -- f x = case x of
+ -- (p::a, q::b) -> (q,p)
+ -- The above should work: the match (p,q) -> (q,p) is polymorphic as
+ -- claimed by the pattern signatures. But if we typechecked the
+ -- match with x in scope and x's type as the expected type, we'd be hosed.
+
+ tcMatchesCase matches res_ty `thenTc` \ (scrut_ty, matches', lie2) ->
+
+ tcAddErrCtxt (caseScrutCtxt scrut) (
+ tcMonoExpr scrut scrut_ty
+ ) `thenTc` \ (scrut',lie1) ->
+
+ returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
+
+tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
= tcAddSrcLoc src_loc $
- tcExpr pred `thenTc` \ (pred',lie1,predTy) ->
-
tcAddErrCtxt (predCtxt pred) (
- unifyTauTy predTy boolTy
- ) `thenTc_`
-
- tcExpr b1 `thenTc` \ (b1',lie2,result_ty) ->
- tcExpr b2 `thenTc` \ (b2',lie3,b2Ty) ->
-
- tcAddErrCtxt (branchCtxt b1 b2) $
- unifyTauTy result_ty b2Ty `thenTc_`
+ 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}
-tcExpr (ListComp expr quals)
- = tcListComp expr quals `thenTc` \ ((expr',quals'), lie, ty) ->
- returnTc (ListComp expr' quals', lie, ty)
+\begin{code}
+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 (HsDo stmts src_loc)
- = -- get the Monad and MonadZero classes
- -- create type consisting of a fresh monad tyvar
- tcAddSrcLoc src_loc $
- newTyVarTy monadKind `thenNF_Tc` \ m ->
- tcDoStmts False m stmts `thenTc` \ ((stmts',monad,mzero), lie, do_ty) ->
+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 boxed) res_ty
+ = (if boxed
+ then unifyTupleTy (length exprs) res_ty
+ else unifyUnboxedTupleTy (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' boxed, plusLIEs lies)
+
+tcMonoExpr expr@(RecordCon con_name rbinds) res_ty
+ = tcAddErrCtxt (recordConCtxt expr) $
+ tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+ let
+ (_, record_ty) = splitFunTys con_tau
+ in
+ ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty ) )
+ unifyTauTy res_ty record_ty `thenTc_`
- -- create dictionaries for monad and possibly monadzero
- (if monad then
- tcLookupClassByKey monadClassKey `thenNF_Tc` \ monadClass ->
- newDicts DoOrigin [(monadClass, m)]
+ -- Check that the record bindings match the constructor
+ -- con_name is syntactically constrained to be a data constructor
+ tcLookupDataCon con_name `thenTc` \ (data_con, _, _) ->
+ let
+ bad_fields = badFields rbinds data_con
+ in
+ if not (null bad_fields) then
+ mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_`
+ failTc -- Fail now, because tcRecordBinds will crash on a bad field
else
- returnNF_Tc (emptyLIE, [panic "TcExpr: MonadZero dictionary"])
- ) `thenNF_Tc` \ (m_lie, [m_id]) ->
- (if mzero then
- tcLookupClassByKey monadZeroClassKey `thenNF_Tc` \ monadZeroClass ->
- newDicts DoOrigin [(monadZeroClass, m)]
- else
- returnNF_Tc (emptyLIE, [panic "TcExpr: MonadZero dictionary"])
- ) `thenNF_Tc` \ (mz_lie, [mz_id]) ->
-
- returnTc (HsDoOut stmts' m_id mz_id src_loc,
- lie `plusLIE` m_lie `plusLIE` mz_lie,
- do_ty)
- where
- monadKind = mkArrowKind mkBoxedTypeKind mkBoxedTypeKind
-\end{code}
-\begin{code}
-tcExpr (ExplicitList [])
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty)
+ -- Typecheck the record bindings
+ tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+
+ let
+ missing_s_fields = missingStrictFields rbinds data_con
+ in
+ checkTcM (null missing_s_fields)
+ (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_`
+ returnNF_Tc ()) `thenNF_Tc_`
+ let
+ missing_fields = missingFields rbinds data_con
+ in
+ checkTcM (not (opt_WarnMissingFields && not (null missing_fields)))
+ (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_`
+ returnNF_Tc ()) `thenNF_Tc_`
+ returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie)
-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)
+-- The main complication with RecordUpd is that we need to explicitly
+-- handle the *non-updated* fields. Consider:
+--
+-- data T a b = MkT1 { fa :: a, fb :: b }
+-- | MkT2 { fa :: a, fc :: Int -> Int }
+-- | MkT3 { fd :: a }
+--
+-- upd :: T a b -> c -> T a c
+-- upd t x = t { fb = x}
+--
+-- The type signature on upd is correct (i.e. the result should not be (T a b))
+-- because upd should be equivalent to:
+--
+-- upd t x = case t of
+-- MkT1 p q -> MkT1 p x
+-- MkT2 a b -> MkT2 p b
+-- MkT3 d -> error ...
+--
+-- So we need to give a completely fresh type to the result record,
+-- and then constrain it by the fields that are *not* updated ("p" above).
+--
+-- Note that because MkT3 doesn't contain all the fields being updated,
+-- its RHS is simply an error, so it doesn't impose any type constraints
+--
+-- All this is done in STEP 4 below.
-tcExpr (ExplicitTuple exprs)
- = tcExprs exprs `thenTc` \ (exprs', lie, tys) ->
- returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys)
+tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty
+ = tcAddErrCtxt (recordUpdCtxt expr) $
-tcExpr (RecordCon (HsVar con) rbinds)
- = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+ -- STEP 0
+ -- Check that the field names are really field names
+ ASSERT( not (null rbinds) )
+ let
+ field_names = [field_name | (field_name, _, _) <- rbinds]
+ in
+ mapNF_Tc tcLookupValueMaybe field_names `thenNF_Tc` \ maybe_sel_ids ->
let
- (_, record_ty) = splitFunTy con_tau
+ bad_guys = [field_name | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids,
+ case maybe_sel_id of
+ Nothing -> True
+ Just sel_id -> not (isRecordSelector sel_id)
+ ]
in
- -- Con is syntactically constrained to be a data constructor
- ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) )
-
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ mapNF_Tc (addErrTc . notSelector) bad_guys `thenTc_`
+ if not (null bad_guys) then
+ failTc
+ else
+
+ -- STEP 1
+ -- Figure out the tycon and data cons from the first field name
+ let
+ (Just sel_id : _) = maybe_sel_ids
+ (_, tau) = ASSERT( isNotUsgTy (idType sel_id) )
+ 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, _) ->
- -- Check that the record bindings match the constructor
- tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
- checkTc (checkRecordFields rbinds con_id)
- (badFieldsCon con rbinds) `thenTc_`
+ -- 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) `thenTc_`
- returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty)
+ -- STEP 3
+ -- Typecheck the update bindings.
+ -- (Do this after checking for bad fields in case there's a field that
+ -- doesn't match the constructor.)
+ let
+ 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
+ -- Use the un-updated fields to find a vector of booleans saying
+ -- which type arguments must be the same in updatee and result.
+ --
+ -- WARNING: this code assumes that all data_cons in a common tycon
+ -- have FieldLabels abstracted over the same tyvars.
+ let
+ upd_field_lbls = [recordSelectorFieldLabel sel_id | (sel_id, _, _) <- rbinds']
+ con_field_lbls_s = map dataConFieldLabels data_cons
--- One small complication in RecordUpd is that we have to generate some
--- dictionaries for the data type context, since we are going to
--- do some construction.
---
--- What dictionaries do we need? For the moment we assume that all
--- data constructors have the same context, and grab it from the first
--- constructor. If they have varying contexts then we'd have to
--- union the ones that could participate in the update.
+ -- A constructor is only relevant to this process if
+ -- it contains all the fields that are being updated
+ relevant_field_lbls_s = filter is_relevant con_field_lbls_s
+ is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls
-tcExpr (RecordUpd record_expr rbinds)
- = ASSERT( not (null rbinds) )
- tcAddErrCtxt recordUpdCtxt $
+ non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
+ common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
- tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ mk_inst_ty (tyvar, result_inst_ty)
+ | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
+ | otherwise = newTyVarTy boxedTypeKind -- Fresh type
+ in
+ mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
- -- Check that the field names are plausible
- zonkTcType record_ty `thenNF_Tc` \ record_ty' ->
+ -- STEP 5
+ -- Typecheck the expression to be updated
let
- (tycon, inst_tys, data_cons) = _trace "TcExpr.getAppDataTyCon" $ getAppDataTyCon record_ty'
- -- The record binds are non-empty (syntax); so at least one field
- -- label will have been unified with record_ty by tcRecordBinds;
- -- field labels must be of data type; hencd the getAppDataTyCon must succeed.
- (tyvars, theta, _, _) = dataConSig (head data_cons)
+ record_ty = mkTyConApp tycon inst_tys
in
- tcInstTheta (zipEqual "tcExpr:RecordUpd" tyvars inst_tys) theta `thenNF_Tc` \ theta' ->
- newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
- checkTc (any (checkRecordFields rbinds) data_cons)
- (badFieldsUpd rbinds) `thenTc_`
+ tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
+
+ -- STEP 6
+ -- Figure out the LIE we need. We have to generate some
+ -- dictionaries for the data type context, since we are going to
+ -- do some construction.
+ --
+ -- What dictionaries do we need? For the moment we assume that all
+ -- data constructors have the same context, and grab it from the first
+ -- constructor. If they have varying contexts then we'd have to
+ -- union the ones that could participate in the update.
+ let
+ (tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
+ inst_env = mkTopTyVarSubst tyvars result_inst_tys
+ theta' = substClasses inst_env theta
+ in
+ newClassDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
- returnTc (RecordUpdOut record_expr' dicts rbinds',
- con_lie `plusLIE` record_lie `plusLIE` rbinds_lie,
- record_ty)
+ -- Phew!
+ returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds',
+ 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 ->
+ tcLookupValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
+ 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_`
-
- tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
+ 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) ->
+ tcLookupValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
+ 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_`
-
- tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
+ 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) ->
+ tcLookupValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
+ 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_`
-
- tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
+ 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) ->
+ tcLookupValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie4, eft_id) ->
+ 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) ->
- tcPolyType poly_ty `thenTc` \ sigma_sig ->
-
- -- Check the tau-type part
- tcSetErrCtxt (exprSigCtxt in_expr) $
- tcInstType [] sigma_sig `thenNF_Tc` \ sigma_sig' ->
- let
- (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
- in
- unifyTauTy tau_ty sig_tau' `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) $
+ tcHsSigType poly_ty `thenTc` \ 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}
+
+Implicit Parameter bindings.
+
+\begin{code}
+tcMonoExpr (HsWith expr binds) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ tcIPBinds binds `thenTc` \ (binds', types, lie2) ->
+ partitionPredsOfLIE isBound lie `thenTc` \ (ips, lie', dict_binds) ->
+ pprTrace "tcMonoExpr With" (ppr (ips, lie', dict_binds)) $
+ let expr'' = if nullMonoBinds dict_binds
+ then expr'
+ else HsLet (mkMonoBind (revBinds dict_binds) [] NonRecursive)
+ expr'
+ in
+ tcCheckIPBinds binds' types ips `thenTc_`
+ returnTc (HsWith expr'' binds', lie' `plusLIE` lie2)
+ where isBound p
+ = case ipName_maybe p of
+ Just n -> n `elem` names
+ Nothing -> False
+ names = map fst binds
+ -- revBinds is used because tcSimplify outputs the bindings
+ -- out-of-order. it's not a problem elsewhere because these
+ -- bindings are normally used in a recursive let
+ -- ZZ probably need to find a better solution
+ revBinds (b1 `AndMonoBinds` b2) =
+ (revBinds b2) `AndMonoBinds` (revBinds b1)
+ revBinds b = b
+
+tcIPBinds ((name, expr) : binds)
+ = newTyVarTy_OpenKind `thenTc` \ ty ->
+ tcGetSrcLoc `thenTc` \ loc ->
+ let id = ipToId name ty loc in
+ tcMonoExpr expr ty `thenTc` \ (expr', lie) ->
+ zonkTcType ty `thenTc` \ ty' ->
+ tcIPBinds binds `thenTc` \ (binds', types, lie2) ->
+ returnTc ((id, expr') : binds', ty : types, lie `plusLIE` lie2)
+tcIPBinds [] = returnTc ([], [], emptyLIE)
+
+tcCheckIPBinds binds types ips
+ = foldrTc tcCheckIPBind (getIPsOfLIE ips) (zip binds types)
+
+-- ZZ how do we use the loc?
+tcCheckIPBind bt@((v, _), t1) ((n, t2) : ips) | getName v == n
+ = unifyTauTy t1 t2 `thenTc_`
+ tcCheckIPBind bt ips `thenTc` \ ips' ->
+ returnTc ips'
+tcCheckIPBind bt (ip : ips)
+ = tcCheckIPBind bt ips `thenTc` \ ips' ->
+ returnTc (ip : ips')
+tcCheckIPBind bt []
+ = returnTc []
+\end{code}
+
+Typecheck expression which in most cases will be an Id.
+
+\begin{code}
+tcExpr_id :: RenamedHsExpr
+ -> TcM s (TcExpr,
+ LIE,
+ TcType)
+tcExpr_id id_expr
+ = case id_expr of
+ HsVar name -> tcId name `thenNF_Tc` \ stuff ->
+ returnTc stuff
+ other -> newTyVarTy_OpenKind `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
- -> TcM s (TcExpr s, [TcExpr s], -- Translated fun and args
- LIE s,
- TcType s) -- Type of the application
-tcApp fun args
+tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
+ -> TcType -- Expected result type of application
+ -> TcM s (TcExpr, [TcExpr], -- Translated fun and args
+ LIE)
+
+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 tidy_env
+ = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' ->
+ zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' ->
+ let
+ (env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
+ (env2, act_ty'') = tidyOpenType env1 act_ty'
+ (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 (env2, 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 -- The type of the function
+ -> Int -- Number of arguments
+ -> TcM s ([TcType], -- Function argument types
+ TcType) -- 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
- -> 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)
- let
- (expected_tyvars, expected_theta, expected_tau) = splitSigmaTy expected_arg_ty
- in
- ASSERT( null expected_theta ) -- And expected_tyvars are all DontBind things
+tcArg :: RenamedHsExpr -- The function (for error messages)
+ -> (RenamedHsExpr, TcType, Int) -- Actual argument and expected arg type
+ -> TcM s (TcExpr, LIE) -- Resulting argument and LIE
- -- Type-check the arg and unify with expected type
- tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy expected_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) $
- tcGetGlobalTyVars `thenNF_Tc` \ env_tyvars ->
- zonkTcTyVars (tyVarsOfType expected_arg_ty) `thenNF_Tc` \ free_tyvars ->
- checkSigTyVarsGivenGlobals
- (env_tyvars `unionTyVarSets` free_tyvars)
- expected_tyvars expected_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 expected_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 expected_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts)
- )
- where
-
- mk_binds [] = EmptyBinds
- mk_binds ((inst,rhs):inst_binds)
- = (SingleBind (NonRecBind (VarMonoBind inst rhs))) `ThenBinds`
- mk_binds inst_binds
+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}
%* *
%************************************************************************
+Between the renamer and the first invocation of the UsageSP inference,
+identifiers read from interface files will have usage information in
+their types, whereas other identifiers will not. The unannotTy here
+in @tcId@ prevents this information from pointlessly propagating
+further prior to the first usage inference.
+
\begin{code}
-tcId :: RnName -> NF_TcM s (TcExpr s, LIE s, TcType s)
+tcId :: Name -> NF_TcM s (TcExpr, LIE, TcType)
tcId name
= -- Look up the Id and instantiate its type
- tcLookupLocalValue name `thenNF_Tc` \ maybe_local ->
-
- (case maybe_local of
- Just tc_id -> let
- (tyvars, rho) = splitForAllTy (idType tc_id)
- in
- tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys', tenv) ->
- let
- rho' = instantiateTy tenv rho
- in
- returnNF_Tc (TcId tc_id, arg_tys', rho')
-
- Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
- let
- (tyvars, rho) = splitForAllTy (idType id)
- in
- tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys, tenv) ->
- tcInstType tenv rho `thenNF_Tc` \ rho' ->
- returnNF_Tc (RealId id, arg_tys, rho')
-
- ) `thenNF_Tc` \ (tc_id_occ, arg_tys, rho) ->
-
- -- Is it overloaded?
- case splitRhoTy rho of
- ([], tau) -> -- Not overloaded, so just make a type application
- returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau)
-
- (theta, tau) -> -- Overloaded, so make a Method inst
- newMethodWithGivenTy (OccurrenceOf tc_id_occ)
- tc_id_occ arg_tys rho `thenNF_Tc` \ (lie, meth_id) ->
- returnNF_Tc (HsVar meth_id, lie, tau)
-\end{code}
+ tcLookupValueMaybe name `thenNF_Tc` \ maybe_local ->
+ case maybe_local of
+ Just tc_id -> instantiate_it (OccurrenceOf tc_id) (HsVar tc_id) (unannotTy (idType tc_id))
+ Nothing -> tcLookupValue name `thenNF_Tc` \ id ->
+ tcInstId id `thenNF_Tc` \ (tyvars, theta, tau) ->
+ instantiate_it2 (OccurrenceOf id) (HsVar id) tyvars theta tau
+
+ where
+ -- The instantiate_it loop runs round instantiating the Id.
+ -- It has to be a loop because we are now prepared to entertain
+ -- types like
+ -- f:: forall a. Eq a => forall b. Baz b => tau
+ -- We want to instantiate this to
+ -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
+ instantiate_it orig fun ty
+ = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) ->
+ tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
+ instantiate_it2 orig fun tyvars theta tau
+
+ instantiate_it2 orig fun tyvars theta tau
+ = if null theta then -- Is it overloaded?
+ returnNF_Tc (mkHsTyApp fun arg_tys, emptyLIE, tau)
+ else
+ -- Yes, it's overloaded
+ instOverloadedFun orig fun arg_tys theta tau `thenNF_Tc` \ (fun', lie1) ->
+ instantiate_it orig fun' tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
+ returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
+
+ where
+ arg_tys = mkTyVarTys tyvars
+\end{code}
%************************************************************************
%* *
-\subsection{@tcQuals@ typchecks list comprehension qualifiers}
+\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
%* *
%************************************************************************
\begin{code}
-tcListComp expr []
- = tcExpr expr `thenTc` \ (expr', lie, ty) ->
- returnTc ((expr',[]), lie, mkListTy ty)
-
-tcListComp expr (qual@(FilterQual filter) : quals)
- = tcAddErrCtxt (qualCtxt qual) (
- tcExpr filter `thenTc` \ (filter', filter_lie, filter_ty) ->
- unifyTauTy boolTy filter_ty `thenTc_`
- returnTc (FilterQual filter', filter_lie)
- ) `thenTc` \ (qual', qual_lie) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), rest_lie, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- qual_lie `plusLIE` rest_lie,
- res_ty)
-
-tcListComp expr (qual@(GeneratorQual pat rhs) : quals)
- = newMonoIds binder_names mkBoxedTypeKind (\ ids ->
-
- tcAddErrCtxt (qualCtxt qual) (
- tcPat pat `thenTc` \ (pat', lie_pat, pat_ty) ->
- tcExpr rhs `thenTc` \ (rhs', lie_rhs, rhs_ty) ->
- -- 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
-
- unifyTauTy (mkListTy pat_ty) rhs_ty `thenTc_`
- returnTc (GeneratorQual pat' rhs',
- lie_pat `plusLIE` lie_rhs)
- ) `thenTc` \ (qual', lie_qual) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), lie_rest, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- lie_qual `plusLIE` lie_rest,
- res_ty)
- )
- where
- binder_names = collectPatBinders pat
+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) )
+ tcAddSrcLoc src_loc $
-tcListComp expr (LetQual binds : quals)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (tcListComp expr quals)
- where
- combine binds' (expr',quals') = (expr', LetQual binds' : quals')
+ newTyVarTy (mkArrowKind boxedTypeKind boxedTypeKind) `thenNF_Tc` \ m ->
+ newTyVarTy boxedTypeKind `thenNF_Tc` \ elt_ty ->
+ unifyTauTy res_ty (mkAppTy m elt_ty) `thenTc_`
+
+ -- If it's a comprehension we're dealing with,
+ -- force it to be a list comprehension.
+ -- (as of Haskell 98, monad comprehensions are no more.)
+ (case do_or_lc of
+ ListComp -> unifyListTy res_ty `thenTc_` returnTc ()
+ _ -> returnTc ()) `thenTc_`
+
+ tcStmts do_or_lc (mkAppTy m) stmts elt_ty `thenTc` \ (stmts', stmts_lie) ->
+
+ -- 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,
+ -- not only for typechecker efficiency, but also because otherwise during
+ -- simplification we end up with silly stuff like
+ -- then = case d of (t,r) -> t
+ -- then = then
+ -- where the second "then" sees that it already exists in the "available" stuff.
+ --
+ tcLookupValueByKey returnMClassOpKey `thenNF_Tc` \ return_sel_id ->
+ tcLookupValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id ->
+ tcLookupValueByKey failMClassOpKey `thenNF_Tc` \ fail_sel_id ->
+ newMethod DoOrigin return_sel_id [m] `thenNF_Tc` \ (return_lie, return_id) ->
+ newMethod DoOrigin then_sel_id [m] `thenNF_Tc` \ (then_lie, then_id) ->
+ newMethod DoOrigin fail_sel_id [m] `thenNF_Tc` \ (fail_lie, fail_id) ->
+ let
+ monad_lie = then_lie `plusLIE` return_lie `plusLIE` fail_lie
+ in
+ returnTc (HsDoOut do_or_lc stmts' return_id then_id fail_id res_ty src_loc,
+ stmts_lie `plusLIE` monad_lie)
\end{code}
%************************************************************************
%* *
-\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
+\subsection{Record bindings}
%* *
%************************************************************************
-\begin{code}
-tcDoStmts :: Bool -- True => require a monad
- -> TcType s -- m
- -> [RenamedStmt]
- -> TcM s (([TcStmt s],
- Bool, -- True => Monad
- Bool), -- True => MonadZero
- LIE s,
- TcType s)
-
-tcDoStmts monad m [stmt@(ExprStmt exp src_loc)]
- = tcAddSrcLoc src_loc $
- tcSetErrCtxt (stmtCtxt stmt) $
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- (if monad then
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy (mkAppTy m a) exp_ty
- else
- returnTc ()
- ) `thenTc_`
- returnTc (([ExprStmt exp' src_loc], monad, False), exp_lie, exp_ty)
-
-tcDoStmts _ m (stmt@(ExprStmt exp src_loc) : stmts)
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy (mkAppTy m a) exp_ty `thenTc_`
- returnTc (ExprStmt exp' src_loc, exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- tcDoStmts True m stmts `thenTc` \ ((stmts', _, mzero), stmts_lie, stmts_ty) ->
- returnTc ((stmt':stmts', True, mzero),
- stmt_lie `plusLIE` stmts_lie,
- stmts_ty)
-
-tcDoStmts _ m (stmt@(BindStmt pat exp src_loc) : stmts)
- = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) ->
-
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- -- See comments with tcListComp on GeneratorQual
-
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy a pat_ty `thenTc_`
- unifyTauTy (mkAppTy m a) exp_ty `thenTc_`
- returnTc (BindStmt pat' exp' src_loc, pat_lie `plusLIE` exp_lie, irrefutablePat pat')
- )) `thenTc` \ (stmt', stmt_lie, failure_free) ->
- tcDoStmts True m stmts `thenTc` \ ((stmts', _, mzero), stmts_lie, stmts_ty) ->
- returnTc ((stmt':stmts', True, mzero || not failure_free),
- stmt_lie `plusLIE` stmts_lie,
- stmts_ty)
-
-tcDoStmts monad m (LetStmt binds : stmts)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (tcDoStmts monad m stmts)
- where
- combine binds' (stmts', monad, mzero) = ((LetStmt binds' : stmts'), monad, mzero)
-
-\end{code}
-
Game plan for record bindings
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For each binding
\begin{code}
tcRecordBinds
- :: TcType s -- Expected type of whole record
+ :: TcType -- Expected type of whole record
-> RenamedRecordBinds
- -> TcM s (TcRecordBinds s, LIE s)
+ -> TcM s (TcRecordBinds, LIE)
tcRecordBinds expected_record_ty rbinds
= mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) ->
returnTc (rbinds', plusLIEs lies)
where
do_bind (field_label, rhs, pun_flag)
- = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
+ = tcLookupValue field_label `thenNF_Tc` \ sel_id ->
+ ASSERT( isRecordSelector sel_id )
+ -- This lookup and assertion will surely succeed, because
+ -- we check that the fields are indeed record selectors
+ -- before calling tcRecordBinds
+
tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
-- 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) ->
- returnTc ((RealId sel_id, rhs', pun_flag), lie)
+ tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) ->
+ returnTc ((sel_id, rhs', pun_flag), lie)
+
+badFields rbinds data_con
+ = [field_name | (field_name, _, _) <- rbinds,
+ not (field_name `elem` field_names)
+ ]
+ where
+ field_names = map fieldLabelName (dataConFieldLabels data_con)
+
+missingStrictFields rbinds data_con
+ = [ fn | fn <- strict_field_names,
+ not (fn `elem` field_names_used)
+ ]
+ where
+ field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
+ strict_field_names = mapMaybe isStrict field_info
+
+ isStrict (fl, MarkedStrict) = Just (fieldLabelName fl)
+ isStrict _ = Nothing
-checkRecordFields :: RenamedRecordBinds -> Id -> Bool -- True iff all the fields in
- -- RecordBinds are field of the
- -- specified constructor
-checkRecordFields rbinds data_con
- = all ok rbinds
- where
- data_con_fields = dataConFieldLabels data_con
+ field_info = zip (dataConFieldLabels data_con)
+ (dataConStrictMarks data_con)
- ok (field_name, _, _) = any (match (getName field_name)) data_con_fields
+missingFields rbinds data_con
+ = [ fn | fn <- non_strict_field_names, not (fn `elem` field_names_used) ]
+ where
+ field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
+
+ -- missing strict fields have already been flagged as
+ -- being so, so leave them out here.
+ non_strict_field_names = mapMaybe isn'tStrict field_info
+
+ isn'tStrict (fl, MarkedStrict) = Nothing
+ isn'tStrict (fl, _) = Just (fieldLabelName fl)
+
+ field_info = zip (dataConFieldLabels data_con)
+ (dataConStrictMarks data_con)
- match field_name field_label = field_name == fieldLabelName field_label
\end{code}
%************************************************************************
%* *
-\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] -> TcM s ([TcExpr], LIE)
-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 -> Pretty -> Pretty
-pp_nest_hang label stuff = ppNest 2 (ppHang (ppStr label) 4 stuff)
+pp_nest_hang :: String -> SDoc -> SDoc
+pp_nest_hang lbl stuff = nest 2 (hang (text lbl) 4 stuff)
\end{code}
Boring and alphabetical:
\begin{code}
-arithSeqCtxt expr sty
- = ppHang (ppStr "In an arithmetic sequence:") 4 (ppr sty expr)
-
-branchCtxt b1 b2 sty
- = ppSep [ppStr "In the branches of a conditional:",
- pp_nest_hang "`then' branch:" (ppr sty b1),
- pp_nest_hang "`else' branch:" (ppr sty b2)]
+arithSeqCtxt expr
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-caseCtxt expr sty
- = ppHang (ppStr "In a case expression:") 4 (ppr sty expr)
+caseCtxt expr
+ = hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
-exprSigCtxt expr sty
- = ppHang (ppStr "In an expression with a type signature:")
- 4 (ppr sty expr)
+caseScrutCtxt expr
+ = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-listCtxt expr sty
- = ppHang (ppStr "In a list expression:") 4 (ppr sty expr)
+exprSigCtxt expr
+ = hang (ptext SLIT("In an expression with a type signature:"))
+ 4 (ppr expr)
-predCtxt expr sty
- = ppHang (ppStr "In a predicate expression:") 4 (ppr sty expr)
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
-sectionRAppCtxt expr sty
- = ppHang (ppStr "In a right section:") 4 (ppr sty expr)
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-sectionLAppCtxt expr sty
- = ppHang (ppStr "In a left section:") 4 (ppr sty expr)
+sectionRAppCtxt expr
+ = hang (ptext SLIT("In the right section:")) 4 (ppr expr)
-funAppCtxt fun arg_no arg sty
- = ppHang (ppCat [ ppStr "In the", speakNth arg_no, ppStr "argument of", ppr sty fun])
- 4 (ppCat [ppStr "namely", ppr sty arg])
+sectionLAppCtxt expr
+ = hang (ptext SLIT("In the left section:")) 4 (ppr expr)
-qualCtxt qual sty
- = ppHang (ppStr "In a list-comprehension qualifer:")
- 4 (ppr sty qual)
+funAppCtxt fun arg arg_no
+ = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
+ quotes (ppr fun) <> text ", namely"])
+ 4 (quotes (ppr arg))
-stmtCtxt stmt sty
- = ppHang (ppStr "In a do statement:")
- 4 (ppr sty stmt)
+wrongArgsCtxt too_many_or_few fun args
+ = hang (ptext SLIT("Probable cause:") <+> quotes (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
- = ppHang (ppStr "Too many arguments in an application of the function")
- 4 (ppr sty f)
+appCtxt fun args
+ = ptext SLIT("In the application") <+> quotes (ppr the_app)
+ where
+ the_app = foldl HsApp fun args -- Used in error messages
-lurkingRank2Err fun fun_ty sty
- = ppHang (ppCat [ppStr "Illegal use of", ppr sty fun])
- 4 (ppAboves [ppStr "It is applied to too few arguments,",
- ppStr "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
- = ppHang (ppStr "In a polymorphic function argument:")
- 4 (ppSep [ppBeside (ppr sty arg) (ppStr " ::"),
- ppr sty expected_arg_ty])
+rank2ArgCtxt arg expected_arg_ty
+ = ptext SLIT("In a polymorphic function argument:") <+> ppr arg
-badFieldsUpd rbinds sty
- = ppHang (ppStr "No constructor has all these fields:")
- 4 (interpp'SP sty fields)
+badFieldsUpd rbinds
+ = hang (ptext SLIT("No constructor has all these fields:"))
+ 4 (pprQuotedList fields)
where
fields = [field | (field, _, _) <- rbinds]
-recordUpdCtxt sty = ppStr "In a record update construct"
+recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr
+recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr
+
+notSelector field
+ = hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
-badFieldsCon con rbinds sty
- = ppHang (ppBesides [ppStr "Inconsistent constructor:", ppr sty con])
- 4 (ppBesides [ppStr "and fields:", interpp'SP sty fields])
+illegalCcallTyErr isArg ty
+ = hang (hsep [ptext SLIT("Unacceptable"), arg_or_res, ptext SLIT("type in _ccall_ or _casm_:")])
+ 4 (hsep [ppr ty])
where
- fields = [field | (field, _, _) <- rbinds]
+ arg_or_res
+ | isArg = ptext SLIT("argument")
+ | otherwise = ptext SLIT("result")
+
+
+missingStrictFieldCon :: Name -> Name -> SDoc
+missingStrictFieldCon con field
+ = hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
+ ptext SLIT("does not have the required strict field"), quotes (ppr field)]
+
+missingFieldCon :: Name -> Name -> SDoc
+missingFieldCon con field
+ = hsep [ptext SLIT("Field") <+> quotes (ppr field),
+ ptext SLIT("is not initialised")]
\end{code}
projects / ghc-hetmet.git / blobdiff