%
-% (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
-
-IMP_Ubiq()
+module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho,
+ tcMonoExpr, tcExpr, tcSyntaxOp
+ ) where
-import HsSyn ( HsExpr(..), Qualifier(..), Stmt(..),
- HsBinds(..), Bind(..), MonoBinds(..),
- ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds,
- Match, Fake, InPat, OutPat, PolyType,
- failureFreePat, collectPatBinders )
-import RnHsSyn ( RenamedHsExpr(..), RenamedQual(..),
- RenamedStmt(..), RenamedRecordBinds(..),
- RnName{-instance Outputable-}
- )
-import TcHsSyn ( TcExpr(..), TcQual(..), TcStmt(..),
- TcIdOcc(..), TcRecordBinds(..),
- mkHsTyApp
- )
+#include "HsVersions.h"
-import TcMonad hiding ( rnMtoTcM )
-import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- LIE(..), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
- newMethod, newMethodWithGivenTy, newDicts )
-import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
- tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars
+#ifdef GHCI /* Only if bootstrapped */
+import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
+import HsSyn ( nlHsVar )
+import Id ( Id )
+import Name ( isExternalName )
+import TcType ( isTauTy )
+import TcEnv ( checkWellStaged )
+import HsSyn ( nlHsApp )
+import qualified DsMeta
+#endif
+
+import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
+ HsMatchContext(..), HsRecordBinds, mkHsApp )
+import TcHsSyn ( hsLitType, (<$>) )
+import TcRnMonad
+import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo,
+ tcSubExp, tcGen, tcSub,
+ unifyFunTys, zapToListTy, zapToTyConApp )
+import BasicTypes ( isMarkedStrict )
+import Inst ( tcOverloadedLit, newMethodFromName, newIPDict,
+ newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall )
+import TcBinds ( tcLocalBinds )
+import TcEnv ( tcLookup, tcLookupId,
+ tcLookupDataCon, tcLookupGlobalId
)
-import TcMatches ( tcMatchesCase, tcMatch )
-import TcMonoType ( tcPolyType )
-import TcPat ( tcPat )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( TcType(..), TcMaybe(..),
- tcInstId, tcInstType, tcInstSigTyVars,
- tcInstSigType, tcInstTcType, tcInstTheta,
- newTyVarTy, zonkTcTyVars, zonkTcType )
-import TcKind ( TcKind )
-
-import Class ( Class(..), classSig )
-import FieldLabel ( fieldLabelName )
-import Id ( idType, dataConFieldLabels, dataConSig, Id(..), GenId )
-import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
-import GenSpecEtc ( checkSigTyVars, checkSigTyVarsGivenGlobals )
-import Name ( Name{-instance Eq-} )
-import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy,
- getTyVar_maybe, getFunTy_maybe, instantiateTy,
- splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy,
- isTauTy, mkFunTys, tyVarsOfType, getForAllTy_maybe,
- getAppDataTyCon, maybeAppDataTyCon
+import TcArrows ( tcProc )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) )
+import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
+import TcPat ( badFieldCon, refineTyVars )
+import TcMType ( tcInstTyVars, tcInstType, newTyFlexiVarTy, zonkTcType )
+import TcType ( TcTyVar, TcType, TcSigmaType, TcRhoType,
+ tcSplitFunTys, mkTyVarTys,
+ isSigmaTy, mkFunTy, mkTyConApp, tyVarsOfTypes, isLinearPred,
+ tcSplitSigmaTy, tidyOpenType
)
-import TyVar ( GenTyVar, TyVarSet(..), unionTyVarSets, mkTyVarSet )
-import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy
+import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
+
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector, isNaughtyRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks,
+ dataConWrapId, isVanillaDataCon, dataConTyVars, dataConOrigArgTys )
+import Name ( Name )
+import TyCon ( TyCon, FieldLabel, tyConStupidTheta, tyConArity, tyConDataCons )
+import Type ( substTheta, substTy )
+import Var ( tyVarKind )
+import VarSet ( emptyVarSet, elemVarSet )
+import TysWiredIn ( boolTy, parrTyCon, tupleTyCon )
+import PrelNames ( enumFromName, enumFromThenName,
+ enumFromToName, enumFromThenToName,
+ enumFromToPName, enumFromThenToPName, negateName
)
-import TysWiredIn ( addrTy,
- boolTy, charTy, stringTy, mkListTy,
- mkTupleTy, mkPrimIoTy
- )
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
- enumFromClassOpKey, enumFromThenClassOpKey,
- enumFromToClassOpKey, enumFromThenToClassOpKey,
- thenMClassOpKey, zeroClassOpKey
- )
---import Name ( Name ) -- Instance
-import Outputable ( interpp'SP )
-import PprType ( GenType, GenTyVar ) -- Instances
-import Maybes ( maybeToBool )
-import Pretty
+import DynFlags
+import StaticFlags ( opt_NoMethodSharing )
+import HscTypes ( TyThing(..) )
+import SrcLoc ( Located(..), unLoc, getLoc )
import Util
-\end{code}
-
-\begin{code}
-tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)
+import ListSetOps ( assocMaybe )
+import Maybes ( catMaybes )
+import Outputable
+import FastString
\end{code}
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{Main wrappers}
%* *
%************************************************************************
\begin{code}
-tcExpr (HsVar name)
- = tcId name `thenNF_Tc` \ (expr', lie, res_ty) ->
+-- tcCheckSigma does type *checking*; it's passed the expected type of the result
+tcCheckSigma :: LHsExpr Name -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM (LHsExpr TcId) -- Generalised expr with expected type
+
+tcCheckSigma expr expected_ty
+ = -- traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
+ tc_expr' expr expected_ty
+
+tc_expr' expr sigma_ty
+ | isSigmaTy sigma_ty
+ = tcGen sigma_ty emptyVarSet (
+ \ rho_ty -> tcCheckRho expr rho_ty
+ ) `thenM` \ (gen_fn, expr') ->
+ returnM (L (getLoc expr') (gen_fn <$> unLoc expr'))
+
+tc_expr' expr rho_ty -- Monomorphic case
+ = tcCheckRho expr rho_ty
+\end{code}
- -- 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_`
+Typecheck expression which in most cases will be an Id.
+The expression can return a higher-ranked type, such as
+ (forall a. a->a) -> Int
+so we must create a hole to pass in as the expected tyvar.
- returnTc (expr', lie, res_ty)
+\begin{code}
+tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
+tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty)
+
+tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType)
+tcInferRho (L loc (HsVar name)) = setSrcSpan loc $ do
+ { (e,_,ty) <- tcId (OccurrenceOf name) name
+ ; return (L loc e, ty) }
+tcInferRho expr = tcInfer (tcMonoExpr expr)
+
+tcSyntaxOp :: InstOrigin -> HsExpr Name -> TcType -> TcM (HsExpr TcId)
+-- Typecheck a syntax operator, checking that it has the specified type
+-- The operator is always a variable at this stage (i.e. renamer output)
+tcSyntaxOp orig (HsVar op) ty = do { (expr', _, id_ty) <- tcId orig op
+ ; co_fn <- tcSub ty id_ty
+ ; returnM (co_fn <$> expr') }
+tcSyntaxOp orig other ty = pprPanic "tcSyntaxOp" (ppr other)
\end{code}
+
+
%************************************************************************
%* *
-\subsection{Literals}
+\subsection{The TAUT rules for variables}TcExpr
%* *
%************************************************************************
-Overloaded literals.
-
\begin{code}
-tcExpr (HsLit (HsInt i))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ 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 ->
-
- newOverloadedLit (LiteralOrigin (HsFrac f))
- (OverloadedFractional f)
- ty `thenNF_Tc` \ (lie, over_lit_id) ->
-
- returnTc (HsVar over_lit_id, lie, ty)
-
-tcExpr (HsLit lit@(HsLitLit s))
- = 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)
+tcMonoExpr :: LHsExpr Name -- Expession to type check
+ -> Expected TcRhoType -- Expected type (could be a type variable)
+ -- Definitely no foralls at the top
+ -- Can be a 'hole'.
+ -> TcM (LHsExpr TcId)
+
+tcMonoExpr (L loc expr) res_ty
+ = setSrcSpan loc (do { expr' <- tcExpr expr res_ty
+ ; return (L loc expr') })
+
+tcExpr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
+tcExpr (HsVar name) res_ty
+ = do { (expr', _, id_ty) <- tcId (OccurrenceOf name) name
+ ; co_fn <- tcSubExp res_ty id_ty
+ ; returnM (co_fn <$> expr') }
+
+tcExpr (HsIPVar ip) res_ty
+ = -- Implicit parameters must have a *tau-type* not a
+ -- type scheme. We enforce this by creating a fresh
+ -- type variable as its type. (Because res_ty may not
+ -- be a tau-type.)
+ newTyFlexiVarTy argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
+ newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
+ extendLIE inst `thenM_`
+ tcSubExp res_ty ip_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> HsIPVar ip')
\end{code}
-Primitive literals:
-
-\begin{code}
-tcExpr (HsLit lit@(HsCharPrim c))
- = returnTc (HsLitOut lit charPrimTy, emptyLIE, charPrimTy)
-
-tcExpr (HsLit lit@(HsStringPrim s))
- = returnTc (HsLitOut lit addrPrimTy, emptyLIE, addrPrimTy)
-
-tcExpr (HsLit lit@(HsIntPrim i))
- = returnTc (HsLitOut lit intPrimTy, emptyLIE, intPrimTy)
-
-tcExpr (HsLit lit@(HsFloatPrim f))
- = returnTc (HsLitOut lit floatPrimTy, emptyLIE, floatPrimTy)
-
-tcExpr (HsLit lit@(HsDoublePrim d))
- = returnTc (HsLitOut lit doublePrimTy, emptyLIE, doublePrimTy)
-\end{code}
-Unoverloaded literals:
+%************************************************************************
+%* *
+\subsection{Expressions type signatures}
+%* *
+%************************************************************************
\begin{code}
-tcExpr (HsLit lit@(HsChar c))
- = returnTc (HsLitOut lit charTy, emptyLIE, charTy)
-
-tcExpr (HsLit lit@(HsString str))
- = returnTc (HsLitOut lit stringTy, emptyLIE, stringTy)
+tcExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = addErrCtxt (exprCtxt in_expr) $
+ tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
+ tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') ->
+ returnM (co_fn <$> ExprWithTySigOut expr' poly_ty)
+
+tcExpr (HsType ty) res_ty
+ = failWithTc (text "Can't handle type argument:" <+> ppr ty)
+ -- This is the syntax for type applications that I was planning
+ -- but there are difficulties (e.g. what order for type args)
+ -- so it's not enabled yet.
+ -- Can't eliminate it altogether from the parser, because the
+ -- same parser parses *patterns*.
\end{code}
+
%************************************************************************
%* *
\subsection{Other expression forms}
%************************************************************************
\begin{code}
-tcExpr (HsPar expr) -- preserve parens so printing needn't guess where they go
- = tcExpr expr
-
-tcExpr (NegApp expr neg) = tcExpr (HsApp neg expr)
-
-tcExpr (HsLam match)
- = tcMatch match `thenTc` \ (match',lie,ty) ->
- returnTc (HsLam match', lie, ty)
-
-tcExpr (HsApp e1 e2) = 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)
-
--- 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)
+tcExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsPar expr')
+tcExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsSCC lbl expr')
+tcExpr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
+ returnM (HsCoreAnn lbl expr')
+
+tcExpr (HsLit lit) res_ty = tcLit lit res_ty
+
+tcExpr (HsOverLit lit) res_ty
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ -- Overloaded literals must have liftedTypeKind, because
+ -- we're instantiating an overloaded function here,
+ -- whereas res_ty might be openTypeKind. This was a bug in 6.2.2
+ tcOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit' ->
+ returnM (HsOverLit lit')
+
+tcExpr (NegApp expr neg_expr) res_ty
+ = do { res_ty' <- zapExpectedType res_ty liftedTypeKind
+ ; neg_expr' <- tcSyntaxOp (OccurrenceOf negateName) neg_expr
+ (mkFunTy res_ty' res_ty')
+ ; expr' <- tcCheckRho expr res_ty'
+ ; return (NegApp expr' neg_expr') }
+
+tcExpr (HsLam match) res_ty
+ = tcMatchLambda match res_ty `thenM` \ match' ->
+ returnM (HsLam match')
+
+tcExpr (HsApp e1 e2) res_ty
+ = tcApp e1 [e2] res_ty
\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) ->
-
- -- Check that res_ty is a function type
- -- Without this check we barf in the desugarer on
- -- f op = (3 `op`)
- -- 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_`
-
- returnTc (SectionL arg' op', lie, res_ty)
+tcExpr in_expr@(SectionL arg1 op) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn ->
+ returnM (co_fn <$> SectionL arg1' op')
-- 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) ->
+tcExpr in_expr@(SectionR op arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn ->
+ returnM (co_fn <$> SectionR op' arg2')
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
- tcAddErrCtxt (sectionRAppCtxt in_expr) $
- unifyTauTy op_ty (mkFunTys [ty1, expr_ty] ty2) `thenTc_`
+-- equivalent to (op e1) e2:
- returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2)
+tcExpr in_expr@(OpApp arg1 op fix arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
+ tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty op_res_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> OpApp arg1' op' fix arg2')
\end{code}
-The interesting thing about @ccall@ is that it is just a template
-which we instantiate by filling in details about the types of its
-argument and result (ie minimal typechecking is performed). So, the
-basic story is that we allocate a load of type variables (to hold the
-arg/result types); unify them with the args/result; and store them for
-later use.
-
\begin{code}
-tcExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty)
- = -- Get the callable and returnable classes.
- tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass ->
-
- let
- new_arg_dict (arg, arg_ty)
- = newDicts (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
+tcExpr (HsLet binds expr) res_ty
+ = do { (binds', expr') <- tcLocalBinds binds $
+ tcMonoExpr expr res_ty
+ ; return (HsLet binds' expr') }
+
+tcExpr in_expr@(HsCase scrut matches) exp_ty
+ = -- We used to typecheck the case alternatives first.
+ -- The case patterns tend to give good type info to use
+ -- when typechecking the scrutinee. For example
+ -- case (map f) of
+ -- (x:xs) -> ...
+ -- will report that map is applied to too few arguments
+ --
+ -- But now, in the GADT world, we need to typecheck the scrutinee
+ -- first, to get type info that may be refined in the case alternatives
+ addErrCtxt (caseScrutCtxt scrut)
+ (tcInferRho scrut) `thenM` \ (scrut', scrut_ty) ->
+
+ addErrCtxt (caseCtxt in_expr) $
+ tcMatchesCase match_ctxt scrut_ty matches exp_ty `thenM` \ matches' ->
+ returnM (HsCase scrut' matches')
+ where
+ match_ctxt = MC { mc_what = CaseAlt,
+ mc_body = tcMonoExpr }
+
+tcExpr (HsIf pred b1 b2) res_ty
+ = addErrCtxt (predCtxt pred)
+ (tcCheckRho pred boolTy) `thenM` \ pred' ->
+
+ zapExpectedType res_ty openTypeKind `thenM` \ res_ty' ->
+ -- C.f. the call to zapToType in TcMatches.tcMatches
+
+ tcCheckRho b1 res_ty' `thenM` \ b1' ->
+ tcCheckRho b2 res_ty' `thenM` \ b2' ->
+ returnM (HsIf pred' b1' b2')
+
+tcExpr (HsDo do_or_lc stmts body _) res_ty
+ = tcDoStmts do_or_lc stmts body res_ty
+
+tcExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
+ = zapToListTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitList elt_ty exprs')
+ where
+ tc_elt elt_ty expr
+ = addErrCtxt (listCtxt expr) $
+ tcCheckRho expr elt_ty
+
+tcExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+ = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty
+ ; exprs' <- mappM (tc_elt elt_ty) exprs
+ ; return (ExplicitPArr elt_ty exprs') }
+ where
+ tc_elt elt_ty expr
+ = addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty)
- -- Arguments
- tcExprs args `thenTc` \ (args', args_lie, arg_tys) ->
+tcExpr (ExplicitTuple exprs boxity) res_ty
+ = do { arg_tys <- zapToTyConApp (tupleTyCon boxity (length exprs)) res_ty
+ ; exprs' <- tcCheckRhos exprs arg_tys
+ ; return (ExplicitTuple exprs' boxity) }
- -- The argument types can be unboxed or boxed; the result
- -- type must, however, be boxed since it's an argument to the PrimIO
- -- type constructor.
- newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ result_ty ->
+tcExpr (HsProc pat cmd) res_ty
+ = tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
+ returnM (HsProc pat' cmd')
- -- 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, _) ->
+tcExpr e@(HsArrApp _ _ _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
- returnTc (CCall lbl args' may_gc is_asm result_ty,
- foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie,
- mkPrimIoTy result_ty)
+tcExpr e@(HsArrForm _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
\end{code}
-\begin{code}
-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)
-
-tcExpr (HsLet binds expr)
- = tcBindsAndThen
- HsLet -- The 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)
- = 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_`
+%************************************************************************
+%* *
+ Record construction and update
+%* *
+%************************************************************************
- returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty)
+\begin{code}
+tcExpr expr@(RecordCon (L loc con_name) _ rbinds) res_ty
+ = addErrCtxt (recordConCtxt expr) $
+ do { (con_expr, _, con_tau) <- setSrcSpan loc $
+ tcId (OccurrenceOf con_name) con_name
+ ; data_con <- tcLookupDataCon con_name
-tcExpr (ListComp expr quals)
- = tcListComp expr quals `thenTc` \ ((expr',quals'), lie, ty) ->
- returnTc (ListComp expr' quals', lie, ty)
-\end{code}
+ ; let (arg_tys, record_ty) = tcSplitFunTys con_tau
+ flds_w_tys = zipEqual "tcExpr RecordCon" (dataConFieldLabels data_con) arg_tys
-\begin{code}
-tcExpr expr@(HsDo stmts src_loc)
- = tcDoStmts stmts src_loc
-\end{code}
+ -- Make the result type line up
+ ; zapExpectedTo res_ty record_ty
-\begin{code}
-tcExpr (ExplicitList [])
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty)
+ -- Typecheck the record bindings
+ ; rbinds' <- tcRecordBinds data_con flds_w_tys rbinds
+
+ -- Check for missing fields
+ ; checkMissingFields data_con rbinds
+ ; returnM (RecordCon (L loc (dataConWrapId data_con)) con_expr rbinds') }
-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)
+tcExpr expr@(RecordUpd record_expr rbinds _ _) res_ty
+ = addErrCtxt (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( notNull rbinds )
+ let
+ field_names = map fst rbinds
+ in
+ mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids ->
+ -- The renamer has already checked that they
+ -- are all in scope
let
- (_, record_ty) = splitFunTy con_tau
+ bad_guys = [ setSrcSpan loc $ addErrTc (notSelector field_name)
+ | (L loc field_name, sel_id) <- field_names `zip` sel_ids,
+ not (isRecordSelector sel_id) -- Excludes class ops
+ ]
+ in
+ checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_`
+
+ -- STEP 1
+ -- Figure out the tycon and data cons from the first field name
+ let
+ -- It's OK to use the non-tc splitters here (for a selector)
+ sel_id : _ = sel_ids
+ (tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
+ data_cons = tyConDataCons tycon -- it's not a field label
in
- -- Con is syntactically constrained to be a data constructor
- ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) )
-
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
-
- -- Check that the record bindings match the constructor
- tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
- checkTc (checkRecordFields rbinds con_id)
- (badFieldsCon con rbinds) `thenTc_`
-
- returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty)
-
--- 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.
-tcExpr (RecordUpd record_expr rbinds)
- = ASSERT( not (null rbinds) )
- tcAddErrCtxt recordUpdCtxt $
+ -- Check that all data cons are vanilla. Doing record updates on GADTs
+ -- and/or existentials is more than my tiny brain can cope with today
+ -- [I think we might be able to manage if none of the selectors is naughty,
+ -- but that's for another day.]
+ checkTc (all isVanillaDataCon data_cons)
+ (nonVanillaUpd tycon) `thenM_`
+
+ -- STEP 2
+ -- Check that at least one constructor has all the named fields
+ -- i.e. has an empty set of bad fields returned by badFields
+ checkTc (any (null . badFields rbinds) data_cons)
+ (badFieldsUpd rbinds) `thenM_`
+
+ -- 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 = recBindFields rbinds
+
+ -- A constructor is only relevant to this process if
+ -- it contains *all* the fields that are being updated
+ relevant_cons = filter is_relevant data_cons
+ is_relevant con = all (`elem` dataConFieldLabels con) upd_field_lbls
+ con1 = head relevant_cons -- A representative constructor
+ con1_tyvars = dataConTyVars con1
+ con1_fld_tys = dataConFieldLabels con1 `zip` dataConOrigArgTys con1
+ common_tyvars = tyVarsOfTypes [ty | (fld,ty) <- con1_fld_tys
+ , not (fld `elem` upd_field_lbls) ]
+
+ is_common_tv tv = tv `elemVarSet` common_tyvars
+
+ mk_inst_ty tv result_inst_ty
+ | is_common_tv tv = returnM result_inst_ty -- Same as result type
+ | otherwise = newTyFlexiVarTy (tyVarKind tv) -- Fresh type, of correct kind
+ in
+ tcInstTyVars con1_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
+ zipWithM mk_inst_ty con1_tyvars result_inst_tys `thenM` \ inst_tys ->
- tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ -- 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
+ inst_fld_tys = [(fld, substTy inst_env ty) | (fld, ty) <- con1_fld_tys]
+ in
+ zapExpectedTo res_ty result_record_ty `thenM_`
+ tcRecordBinds con1 inst_fld_tys rbinds `thenM` \ rbinds' ->
- -- 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 = ASSERT( length inst_tys == tyConArity tycon )
+ mkTyConApp tycon inst_tys
+ -- This is one place where the isVanilla check is important
+ -- So that inst_tys matches the tycon
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_`
-
- returnTc (RecordUpdOut record_expr' dicts rbinds',
- con_lie `plusLIE` record_lie `plusLIE` rbinds_lie,
- record_ty)
-
-tcExpr (ArithSeqIn seq@(From expr))
- = tcExpr expr `thenTc` \ (expr', lie1, ty) ->
-
- tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [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 ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `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 ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `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 ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie4, eft_id) ->
-
- returnTc (ArithSeqOut (HsVar eft_id)
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4,
- mkListTy ty1)
+ tcCheckRho record_expr record_ty `thenM` \ record_expr' ->
+
+ -- 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 pattern matching over the data cons.
+ --
+ -- What dictionaries do we need?
+ -- We just take the context of the first data constructor
+ -- This isn't right, but I just can't bear to union up all the relevant ones
+ let
+ theta' = substTheta inst_env (tyConStupidTheta tycon)
+ in
+ newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
+
+ -- Phew!
+ returnM (RecordUpd record_expr' rbinds' record_ty result_record_ty)
\end{code}
+
%************************************************************************
%* *
-\subsection{Expressions type signatures}
+ Arithmetic sequences e.g. [a,b..]
+ and their parallel-array counterparts e.g. [: a,b.. :]
+
%* *
%************************************************************************
\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) $
- tcInstSigType 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)
+tcExpr (ArithSeq _ seq@(From expr)) res_ty
+ = zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr elt_ty `thenM` \ expr' ->
+
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromName `thenM` \ enum_from ->
+
+ returnM (ArithSeq (HsVar enum_from) (From expr'))
+
+tcExpr in_expr@(ArithSeq _ seq@(FromThen expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenName `thenM` \ enum_from_then ->
+
+ returnM (ArithSeq (HsVar enum_from_then) (FromThen expr1' expr2'))
+
+
+tcExpr in_expr@(ArithSeq _ seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromToName `thenM` \ enum_from_to ->
+
+ returnM (ArithSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
+
+tcExpr in_expr@(ArithSeq _ seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenToName `thenM` \ eft ->
+
+ returnM (ArithSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+tcExpr in_expr@(PArrSeq _ seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromToPName `thenM` \ enum_from_to ->
+
+ returnM (PArrSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
+
+tcExpr in_expr@(PArrSeq _ seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromThenToPName `thenM` \ eft ->
+
+ returnM (PArrSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+tcExpr (PArrSeq _ _) _
+ = panic "TcExpr.tcMonoExpr: Infinite parallel array!"
+ -- the parser shouldn't have generated it and the renamer shouldn't have
+ -- let it through
\end{code}
+
%************************************************************************
%* *
-\subsection{@tcApp@ typchecks an application}
+ Template Haskell
%* *
%************************************************************************
\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
- = -- 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) ->
-
- tcApp_help fun 1 fun_ty args `thenTc` \ (args', lie_args, res_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_`
-
- returnTc (fun', args', lie_fun `plusLIE` lie_args, res_ty)
-
-
-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
-
-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) ->
-
- -- 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) ->
+#ifdef GHCI /* Only if bootstrapped */
+ -- Rename excludes these cases otherwise
+tcExpr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty
+tcExpr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty
+ ; return (unLoc e) }
+#endif /* GHCI */
+\end{code}
- -- Done
- returnTc (arg':args', lie_arg `plusLIE` lie_args, res_ty)
-\end{code}
+%************************************************************************
+%* *
+ Catch-all
+%* *
+%************************************************************************
\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)
-
- -- 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.
- let
- (expected_tyvars, expected_theta, expected_tau) = splitSigmaTy expected_arg_ty
- in
- ASSERT( null expected_theta ) -- And expected_tyvars are all DontBind things
- tcInstSigTyVars expected_tyvars `thenNF_Tc` \ (sig_tyvars, sig_tyvar_tys, _) ->
- unifyTauTyLists (mkTyVarTys expected_tyvars) sig_tyvar_tys `thenTc_`
-
- -- 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) $
- checkSigTyVarsGivenGlobals
- (tyVarsOfType expected_arg_ty)
- 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
+tcExpr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
+
%************************************************************************
%* *
-\subsection{@tcId@ typchecks an identifier occurrence}
+\subsection{@tcApp@ typchecks an application}
%* *
%************************************************************************
\begin{code}
-tcId :: RnName -> NF_TcM s (TcExpr s, LIE s, TcType s)
-tcId name
- = -- Look up the Id and instantiate its type
- tcLookupLocalValue name `thenNF_Tc` \ maybe_local ->
+tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args
+ -> Expected TcRhoType -- Expected result type of application
+ -> TcM (HsExpr TcId) -- Translated fun and args
+
+tcApp (L _ (HsApp e1 e2)) args res_ty
+ = tcApp e1 (e2:args) res_ty -- Accumulate the arguments
+
+tcApp fun args res_ty
+ = do { let n_args = length args
+ ; (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
+
+ -- Extract its argument types
+ ; (expected_arg_tys, actual_res_ty)
+ <- do { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau))
+ ; let msg = sep [ptext SLIT("The function") <+> quotes (ppr fun),
+ ptext SLIT("is applied to")
+ <+> speakN n_args <+> ptext SLIT("arguments")]
+ ; unifyFunTys msg n_args fun_tau }
+
+ ; case res_ty of
+ Check _ -> do -- Connect to result type first
+ -- See Note [Push result type in]
+ { co_fn <- tcResult fun args res_ty actual_res_ty
+ ; the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; traceTc (text "tcApp: check" <+> vcat [ppr fun <+> ppr args,
+ ppr the_app', ppr actual_res_ty])
+ ; returnM (co_fn <$> the_app') }
+
+ Infer _ -> do -- Type check args first, then
+ -- refine result type, then do tcResult
+ { the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; subst <- refineTyVars fun_tvs
+ ; let actual_res_ty' = substTy subst actual_res_ty
+ ; co_fn <- tcResult fun args res_ty actual_res_ty'
+ ; traceTc (text "tcApp: infer" <+> vcat [ppr fun <+> ppr args, ppr the_app',
+ ppr actual_res_ty, ppr actual_res_ty'])
+ ; returnM (co_fn <$> the_app') }
+ }
+
+-- Note [Push result type in]
+--
+-- Unify with expected result before (was: after) type-checking the args
+-- so that the info from res_ty (was: args) percolates to args (was actual_res_ty).
+-- This is when we might detect a too-few args situation.
+-- (One can think of cases when the opposite order would give
+-- a better error message.)
+-- [March 2003: I'm experimenting with putting this first. Here's an
+-- example where it actually makes a real difference
+-- class C t a b | t a -> b
+-- instance C Char a Bool
+--
+-- data P t a = forall b. (C t a b) => MkP b
+-- data Q t = MkQ (forall a. P t a)
- case maybe_local of
- Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id)
+-- f1, f2 :: Q Char;
+-- f1 = MkQ (MkP True)
+-- f2 = MkQ (MkP True :: forall a. P Char a)
+--
+-- With the change, f1 will type-check, because the 'Char' info from
+-- the signature is propagated into MkQ's argument. With the check
+-- in the other order, the extra signature in f2 is reqd.]
+
+----------------
+tcFun :: LHsExpr Name -> TcM (LHsExpr TcId, [TcTyVar], TcRhoType)
+-- Instantiate the function, returning the type variables used
+-- If the function isn't simple, infer its type, and return no
+-- type variables
+tcFun (L loc (HsVar f)) = setSrcSpan loc $ do
+ { (fun', tvs, fun_tau) <- tcId (OccurrenceOf f) f
+ ; return (L loc fun', tvs, fun_tau) }
+tcFun fun = do { (fun', fun_tau) <- tcInfer (tcMonoExpr fun)
+ ; return (fun', [], fun_tau) }
+
+----------------
+tcArgs :: LHsExpr Name -- The function (for error messages)
+ -> LHsExpr TcId -- The function (to build into result)
+ -> [LHsExpr Name] -> [TcSigmaType] -- Actual arguments and expected arg types
+ -> TcM (HsExpr TcId) -- Resulting application
+
+tcArgs fun fun' args expected_arg_tys
+ = do { args' <- mappM (tcArg fun) (zip3 args expected_arg_tys [1..])
+ ; return (unLoc (foldl mkHsApp fun' args')) }
+
+tcArg :: LHsExpr Name -- The function (for error messages)
+ -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (LHsExpr TcId) -- Resulting argument
+tcArg fun (arg, ty, arg_no) = addErrCtxt (funAppCtxt fun arg arg_no)
+ (tcCheckSigma arg ty)
+
+----------------
+tcResult fun args res_ty actual_res_ty
+ = addErrCtxtM (checkArgsCtxt fun args res_ty actual_res_ty)
+ (tcSubExp res_ty actual_res_ty)
+
+----------------
+-- If an error happens we try to figure out whether the
+-- function has been given too many or too few arguments,
+-- and say so.
+-- The ~(Check...) is because in the Infer case the tcSubExp
+-- definitely won't fail, so we can be certain we're in the Check branch
+checkArgsCtxt fun args (Infer _) actual_res_ty tidy_env
+ = return (tidy_env, ptext SLIT("Urk infer"))
+
+checkArgsCtxt fun args (Check expected_res_ty) actual_res_ty tidy_env
+ = zonkTcType expected_res_ty `thenM` \ exp_ty' ->
+ zonkTcType actual_res_ty `thenM` \ act_ty' ->
+ let
+ (env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
+ (env2, act_ty'') = tidyOpenType env1 act_ty'
+ (exp_args, _) = tcSplitFunTys exp_ty''
+ (act_args, _) = tcSplitFunTys act_ty''
- Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
- tcInstType [] (idType id) `thenNF_Tc` \ inst_ty ->
- let
- (tyvars, rho) = splitForAllTy inst_ty
- in
- instantiate_it2 (RealId id) tyvars rho
+ len_act_args = length act_args
+ len_exp_args = length exp_args
+ message | len_exp_args < len_act_args = wrongArgsCtxt "too few" fun args
+ | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args
+ | otherwise = appCtxt fun args
+ in
+ returnM (env2, message)
+
+----------------
+unifyInfixTy :: LHsExpr Name -> HsExpr Name -> TcType
+ -> TcM ([TcType], TcType)
+-- This wrapper just prepares the error message for unifyFunTys
+unifyInfixTy op expr op_ty
+ = unifyFunTys msg 2 op_ty
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 tc_id_occ ty
- = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) ->
- instantiate_it2 tc_id_occ tyvars rho
-
- instantiate_it2 tc_id_occ tyvars rho
- | null theta -- Is it overloaded?
- = returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau)
-
- | otherwise -- 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) ->
- returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
-
- where
- (theta, tau) = splitRhoTy rho
- arg_tys = mkTyVarTys tyvars
+ msg = sep [herald <+> quotes (ppr expr),
+ ptext SLIT("requires") <+> quotes (ppr op)
+ <+> ptext SLIT("to take two arguments")]
+ herald = case expr of
+ OpApp _ _ _ _ -> ptext SLIT("The infix expression")
+ other -> ptext SLIT("The operator section")
\end{code}
+
%************************************************************************
%* *
-\subsection{@tcQuals@ typechecks list-comprehension qualifiers}
+\subsection{@tcId@ typchecks an identifier occurrence}
%* *
%************************************************************************
+tcId instantiates an occurrence of an Id.
+The instantiate_it loop runs round instantiating the Id.
+It has to be a loop because we are now prepared to entertain
+types like
+ f:: forall a. Eq a => forall b. Baz b => tau
+We want to instantiate this to
+ f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
+
+The -fno-method-sharing flag controls what happens so far as the LIE
+is concerned. The default case is that for an overloaded function we
+generate a "method" Id, and add the Method Inst to the LIE. So you get
+something like
+ f :: Num a => a -> a
+ f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x
+If you specify -fno-method-sharing, the dictionary application
+isn't shared, so we get
+ f :: Num a => a -> a
+ f = /\a (d:Num a) (x:a) -> (+) a d x x
+This gets a bit less sharing, but
+ a) it's better for RULEs involving overloaded functions
+ b) perhaps fewer separated lambdas
+
\begin{code}
-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)
- )
+tcId :: InstOrigin -> Name -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ -- Return the type variables at which the function
+ -- is instantiated, as well as the translated variable and its type
+
+tcId orig id_name -- Look up the Id and instantiate its type
+ = tcLookup id_name `thenM` \ thing ->
+ case thing of {
+ AGlobal (ADataCon con) -- Similar, but instantiate the stupid theta too
+ -> do { (expr, tvs, tau) <- instantiate (dataConWrapId con)
+ ; tcInstStupidTheta con (mkTyVarTys tvs)
+ -- Remember to chuck in the constraints from the "silly context"
+ ; return (expr, tvs, tau) }
+
+ ; AGlobal (AnId id) | isNaughtyRecordSelector id
+ -> failWithTc (naughtyRecordSel id)
+ ; AGlobal (AnId id) -> instantiate id
+ -- A global cannot possibly be ill-staged
+ -- nor does it need the 'lifting' treatment
+
+ ; ATcId id th_level -> tc_local_id id th_level
+
+ ; other -> failWithTc (ppr other <+> ptext SLIT("used where a value identifer was expected"))
+ }
where
- binder_names = collectPatBinders pat
-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')
+#ifndef GHCI
+ tc_local_id id th_bind_lvl -- Non-TH case
+ = instantiate id
+
+#else /* GHCI and TH is on */
+ tc_local_id id th_bind_lvl -- TH case
+ = -- Check for cross-stage lifting
+ getStage `thenM` \ use_stage ->
+ case use_stage of
+ Brack use_lvl ps_var lie_var
+ | use_lvl > th_bind_lvl
+ -> if isExternalName id_name then
+ -- Top-level identifiers in this module,
+ -- (which have External Names)
+ -- are just like the imported case:
+ -- no need for the 'lifting' treatment
+ -- E.g. this is fine:
+ -- f x = x
+ -- g y = [| f 3 |]
+ -- But we do need to put f into the keep-alive
+ -- set, because after desugaring the code will
+ -- only mention f's *name*, not f itself.
+ keepAliveTc id_name `thenM_`
+ instantiate id
+
+ else -- Nested identifiers, such as 'x' in
+ -- E.g. \x -> [| h x |]
+ -- We must behave as if the reference to x was
+ -- h $(lift x)
+ -- We use 'x' itself as the splice proxy, used by
+ -- the desugarer to stitch it all back together.
+ -- If 'x' occurs many times we may get many identical
+ -- bindings of the same splice proxy, but that doesn't
+ -- matter, although it's a mite untidy.
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((id_name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
+
+ returnM (HsVar id, [], id_ty))
+
+ other ->
+ checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
+ instantiate id
+#endif /* GHCI */
+
+ instantiate :: TcId -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ instantiate fun_id = loop (HsVar fun_id) [] (idType fun_id)
+
+ loop (HsVar fun_id) tvs fun_ty
+ | want_method_inst fun_ty
+ = tcInstType fun_ty `thenM` \ (tyvars, theta, tau) ->
+ newMethodWithGivenTy orig fun_id
+ (mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
+ loop (HsVar meth_id) (tvs ++ tyvars) tau
+
+ loop fun tvs fun_ty
+ | isSigmaTy fun_ty
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, new_tvs, tau) ->
+ loop (inst_fn <$> fun) (tvs ++ new_tvs) tau
+
+ | otherwise
+ = returnM (fun, tvs, fun_ty)
+
+ -- Hack Alert (want_method_inst)!
+ -- If f :: (%x :: T) => Int -> Int
+ -- Then if we have two separate calls, (f 3, f 4), we cannot
+ -- make a method constraint that then gets shared, thus:
+ -- let m = f %x in (m 3, m 4)
+ -- because that loses the linearity of the constraint.
+ -- The simplest thing to do is never to construct a method constraint
+ -- in the first place that has a linear implicit parameter in it.
+ want_method_inst fun_ty
+ | opt_NoMethodSharing = False
+ | otherwise = case tcSplitSigmaTy fun_ty of
+ (_,[],_) -> False -- Not overloaded
+ (_,theta,_) -> not (any isLinearPred theta)
\end{code}
-
%************************************************************************
%* *
-\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
+\subsection{Record bindings}
%* *
%************************************************************************
-\begin{code}
-tcDoStmts stmts src_loc
- = -- get the Monad and MonadZero classes
- -- create type consisting of a fresh monad tyvar
- tcAddSrcLoc src_loc $
- newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m ->
-
-
- -- Build the then and zero methods in case we need them
- tcLookupGlobalValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id ->
- tcLookupGlobalValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id ->
- newMethod DoOrigin
- (RealId then_sel_id) [m] `thenNF_Tc` \ (m_lie, then_id) ->
- newMethod DoOrigin
- (RealId zero_sel_id) [m] `thenNF_Tc` \ (mz_lie, zero_id) ->
-
- let
- get_m_arg ty
- = newTyVarTy mkTypeKind `thenNF_Tc` \ arg_ty ->
- unifyTauTy (mkAppTy m arg_ty) ty `thenTc_`
- returnTc arg_ty
-
- go [stmt@(ExprStmt exp src_loc)]
- = tcAddSrcLoc src_loc $
- tcSetErrCtxt (stmtCtxt stmt) $
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- returnTc ([ExprStmt exp' src_loc], exp_lie, exp_ty)
-
- go (stmt@(ExprStmt exp src_loc) : stmts)
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- get_m_arg exp_ty `thenTc` \ a ->
- returnTc (a, exp', exp_lie)
- )) `thenTc` \ (a, exp', exp_lie) ->
- go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) ->
- get_m_arg stmts_ty `thenTc` \ b ->
- returnTc (ExprStmtOut exp' src_loc a b : stmts',
- exp_lie `plusLIE` stmts_lie `plusLIE` m_lie,
- stmts_ty)
-
- go (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
-
- get_m_arg exp_ty `thenTc` \ a ->
- unifyTauTy a pat_ty `thenTc_`
- returnTc (a, pat', exp', pat_lie `plusLIE` exp_lie)
- )) `thenTc` \ (a, pat', exp', stmt_lie) ->
- go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) ->
- get_m_arg stmts_ty `thenTc` \ b ->
- returnTc (BindStmtOut pat' exp' src_loc a b : stmts',
- stmt_lie `plusLIE` stmts_lie `plusLIE` m_lie `plusLIE`
- (if failureFreePat pat' then emptyLIE else mz_lie),
- stmts_ty)
-
- go (LetStmt binds : stmts)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (go stmts)
- where
- combine binds' stmts' = LetStmt binds' : stmts'
- in
-
- go stmts `thenTc` \ (stmts', final_lie, final_ty) ->
- returnTc (HsDoOut stmts' then_id zero_id src_loc,
- final_lie,
- final_ty)
-\end{code}
-
Game plan for record bindings
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-For each binding
- field = value
-1. look up "field", to find its selector Id, which must have type
- forall a1..an. T a1 .. an -> tau
- where tau is the type of the field.
+1. Find the TyCon for the bindings, from the first field label.
+
+2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty.
-2. Instantiate this type
+For each binding field = value
-3. Unify the (T a1 .. an) part with the "expected result type", which
- is passed in. This checks that all the field labels come from the
- same type.
+3. Instantiate the field type (from the field label) using the type
+ envt from step 2.
-4. Type check the value using tcArg, passing tau as the expected
- argument type.
+4 Type check the value using tcArg, passing the field type as
+ the expected argument type.
This extends OK when the field types are universally quantified.
-Actually, to save excessive creation of fresh type variables,
-we
\begin{code}
tcRecordBinds
- :: TcType s -- Expected type of whole record
- -> RenamedRecordBinds
- -> TcM s (TcRecordBinds s, LIE s)
+ :: DataCon
+ -> [(FieldLabel,TcType)] -- Expected type for each field
+ -> HsRecordBinds Name
+ -> TcM (HsRecordBinds TcId)
+
+tcRecordBinds data_con flds_w_tys rbinds
+ = do { mb_binds <- mappM do_bind rbinds
+ ; return (catMaybes mb_binds) }
+ where
+ do_bind (L loc field_lbl, rhs)
+ | Just field_ty <- assocMaybe flds_w_tys field_lbl
+ = addErrCtxt (fieldCtxt field_lbl) $
+ do { rhs' <- tcCheckSigma rhs field_ty
+ ; sel_id <- tcLookupId field_lbl
+ ; ASSERT( isRecordSelector sel_id )
+ return (Just (L loc sel_id, rhs')) }
+ | otherwise
+ = do { addErrTc (badFieldCon data_con field_lbl)
+ ; return Nothing }
+
+badFields rbinds data_con
+ = filter (not . (`elem` field_names)) (recBindFields rbinds)
+ where
+ field_names = dataConFieldLabels data_con
+
+checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM ()
+checkMissingFields data_con rbinds
+ | null field_labels -- Not declared as a record;
+ -- But C{} is still valid if no strict fields
+ = if any isMarkedStrict field_strs then
+ -- Illegal if any arg is strict
+ addErrTc (missingStrictFields data_con [])
+ else
+ returnM ()
+
+ | otherwise -- A record
+ = checkM (null missing_s_fields)
+ (addErrTc (missingStrictFields data_con missing_s_fields)) `thenM_`
+
+ doptM Opt_WarnMissingFields `thenM` \ warn ->
+ checkM (not (warn && notNull missing_ns_fields))
+ (warnTc True (missingFields data_con missing_ns_fields))
-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 ->
- tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
-
- -- Record selectors all have type
- -- forall a1..an. T a1 .. an -> tau
- ASSERT( maybeToBool (getFunTy_maybe tau) )
- let
- -- Selector must have type RecordType -> FieldType
- Just (record_ty, field_ty) = getFunTy_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)
-
-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
-
- ok (field_name, _, _) = any (match (getName field_name)) data_con_fields
-
- match field_name field_label = field_name == fieldLabelName field_label
+ missing_s_fields
+ = [ fl | (fl, str) <- field_info,
+ isMarkedStrict str,
+ not (fl `elem` field_names_used)
+ ]
+ missing_ns_fields
+ = [ fl | (fl, str) <- field_info,
+ not (isMarkedStrict str),
+ not (fl `elem` field_names_used)
+ ]
+
+ field_names_used = recBindFields rbinds
+ field_labels = dataConFieldLabels data_con
+
+ field_info = zipEqual "missingFields"
+ field_labels
+ field_strs
+
+ field_strs = dataConStrictMarks data_con
\end{code}
%************************************************************************
%* *
-\subsection{@tcExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions}
%* *
%************************************************************************
\begin{code}
-tcExprs :: [RenamedHsExpr] -> TcM s ([TcExpr s], LIE s, [TcType 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)
+tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId]
+
+tcCheckRhos [] [] = returnM []
+tcCheckRhos (expr:exprs) (ty:tys)
+ = tcCheckRho expr ty `thenM` \ expr' ->
+ tcCheckRhos exprs tys `thenM` \ exprs' ->
+ returnM (expr':exprs')
+tcCheckRhos exprs tys = pprPanic "tcCheckRhos" (ppr exprs $$ ppr tys)
\end{code}
-% =================================================
+%************************************************************************
+%* *
+\subsection{Literals}
+%* *
+%************************************************************************
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
+Overloaded literals.
-Mini-utils:
\begin{code}
-pp_nest_hang :: String -> Pretty -> Pretty
-pp_nest_hang label stuff = ppNest 2 (ppHang (ppStr label) 4 stuff)
+tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId)
+tcLit lit res_ty
+ = zapExpectedTo res_ty (hsLitType lit) `thenM_`
+ returnM (HsLit lit)
\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)]
-
-caseCtxt expr sty
- = ppHang (ppStr "In a case expression:") 4 (ppr sty expr)
-exprSigCtxt expr sty
- = ppHang (ppStr "In an expression with a type signature:")
- 4 (ppr sty expr)
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
-listCtxt expr sty
- = ppHang (ppStr "In a list expression:") 4 (ppr sty expr)
+Boring and alphabetical:
+\begin{code}
+arithSeqCtxt expr
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-predCtxt expr sty
- = ppHang (ppStr "In a predicate expression:") 4 (ppr sty expr)
+parrSeqCtxt expr
+ = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
-sectionRAppCtxt expr sty
- = ppHang (ppStr "In a right section:") 4 (ppr sty expr)
+caseCtxt expr
+ = hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
-sectionLAppCtxt expr sty
- = ppHang (ppStr "In a left section:") 4 (ppr sty expr)
+caseScrutCtxt expr
+ = hang (ptext SLIT("In the scrutinee of a case expression:")) 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])
+exprCtxt expr
+ = hang (ptext SLIT("In the expression:")) 4 (ppr expr)
-qualCtxt qual sty
- = ppHang (ppStr "In a list-comprehension qualifer:")
- 4 (ppr sty qual)
+fieldCtxt field_name
+ = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record")
-stmtCtxt stmt sty
- = ppHang (ppStr "In a do statement:")
- 4 (ppr sty stmt)
+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))
-tooManyArgsCtxt f sty
- = ppHang (ppStr "Too many arguments in an application of the function")
- 4 (ppr sty f)
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
-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"])
+parrCtxt expr
+ = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr)
-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])
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-badFieldsUpd rbinds sty
- = ppHang (ppStr "No constructor has all these fields:")
- 4 (interpp'SP sty fields)
+appCtxt fun args
+ = ptext SLIT("In the application") <+> quotes (ppr the_app)
where
- fields = [field | (field, _, _) <- rbinds]
-
-recordUpdCtxt sty = ppStr "In a record update construct"
-
-badFieldsCon con rbinds sty
- = ppHang (ppBesides [ppStr "Inconsistent constructor:", ppr sty con])
- 4 (ppBesides [ppStr "and fields:", interpp'SP sty fields])
+ the_app = foldl mkHsApp fun args -- Used in error messages
+
+nonVanillaUpd tycon
+ = vcat [ptext SLIT("Record update for the non-Haskell-98 data type") <+> quotes (ppr tycon)
+ <+> ptext SLIT("is not (yet) supported"),
+ ptext SLIT("Use pattern-matching instead")]
+badFieldsUpd rbinds
+ = hang (ptext SLIT("No constructor has all these fields:"))
+ 4 (pprQuotedList (recBindFields rbinds))
+
+recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr
+recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr
+
+naughtyRecordSel sel_id
+ = ptext SLIT("Cannot use record selector") <+> quotes (ppr sel_id) <+>
+ ptext SLIT("as a function due to escaped type variables") $$
+ ptext SLIT("Probably fix: use pattern-matching syntax instead")
+
+notSelector field
+ = hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
+
+missingStrictFields :: DataCon -> [FieldLabel] -> SDoc
+missingStrictFields con fields
+ = header <> rest
where
- fields = [field | (field, _, _) <- rbinds]
+ rest | null fields = empty -- Happens for non-record constructors
+ -- with strict fields
+ | otherwise = colon <+> pprWithCommas ppr fields
+
+ header = ptext SLIT("Constructor") <+> quotes (ppr con) <+>
+ ptext SLIT("does not have the required strict field(s)")
+
+missingFields :: DataCon -> [FieldLabel] -> SDoc
+missingFields con fields
+ = ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:")
+ <+> pprWithCommas ppr fields
+
+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 mkHsApp fun args -- Used in error messages
+
+#ifdef GHCI
+polySpliceErr :: Id -> SDoc
+polySpliceErr id
+ = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
+#endif
\end{code}
projects / ghc-hetmet.git / blobdiff