\section[TcExpr]{Typecheck an expression}
\begin{code}
-module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where
+module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho,
+ tcMonoExpr, tcExpr, tcSyntaxOp
+ ) where
#include "HsVersions.h"
#ifdef GHCI /* Only if bootstrapped */
import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
-import HsSyn ( HsReify(..), ReifyFlavour(..) )
-import TcType ( isTauTy )
-import TcEnv ( bracketOK, tcMetaTy, checkWellStaged )
+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(..), HsLit(..), ArithSeqInfo(..), recBindFields )
-import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, mkHsLet, (<$>) )
+import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
+ HsMatchContext(..), HsRecordBinds, mkHsApp )
+import TcHsSyn ( hsLitType, (<$>) )
import TcRnMonad
-import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
- unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy )
+import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo,
+ tcSubExp, tcGen, tcSub,
+ unifyFunTys, zapToListTy, zapToTyConApp )
import BasicTypes ( isMarkedStrict )
-import Inst ( InstOrigin(..),
- newOverloadedLit, newMethodFromName, newIPDict,
- newDicts, newMethodWithGivenTy,
- instToId, tcInstCall, tcInstDataCon
- )
-import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupClass, tcLookupGlobal_maybe, tcLookup,
- tcLookupTyCon, tcLookupDataCon, tcLookupId, checkProcLevel
+import Inst ( tcOverloadedLit, newMethodFromName, newIPDict,
+ newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall )
+import TcBinds ( tcLocalBinds )
+import TcEnv ( tcLookup, tcLookupId,
+ tcLookupDataCon, tcLookupGlobalId
)
import TcArrows ( tcProc )
-import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig )
-import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
-import TcPat ( badFieldCon )
-import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, newTyVarTys, zonkTcType )
-import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
- tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
- isSigmaTy, mkFunTy, mkFunTys,
- mkTyConApp, mkClassPred,
- tyVarsOfTypes, isLinearPred,
- liftedTypeKind, openTypeKind,
+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 FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector )
-import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks, dataConWrapId )
+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, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
-import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import TyCon ( TyCon, FieldLabel, tyConStupidTheta, tyConArity, tyConDataCons )
+import Type ( substTheta, substTy )
+import Var ( tyVarKind )
import VarSet ( emptyVarSet, elemVarSet )
-import TysWiredIn ( boolTy )
-import PrelNames ( cCallableClassName, cReturnableClassName,
- enumFromName, enumFromThenName,
+import TysWiredIn ( boolTy, parrTyCon, tupleTyCon )
+import PrelNames ( enumFromName, enumFromThenName,
enumFromToName, enumFromThenToName,
- enumFromToPName, enumFromThenToPName,
- ioTyConName
+ enumFromToPName, enumFromThenToPName, negateName
)
-import ListSetOps ( minusList )
-import CmdLineOpts
+import DynFlags
+import StaticFlags ( opt_NoMethodSharing )
import HscTypes ( TyThing(..) )
-
+import SrcLoc ( Located(..), unLoc, getLoc )
import Util
+import ListSetOps ( assocMaybe )
+import Maybes ( catMaybes )
import Outputable
import FastString
\end{code}
\begin{code}
-- tcCheckSigma does type *checking*; it's passed the expected type of the result
-tcCheckSigma :: RenamedHsExpr -- Expession to type check
+tcCheckSigma :: LHsExpr Name -- Expession to type check
-> TcSigmaType -- Expected type (could be a polytpye)
- -> TcM TcExpr -- Generalised expr with expected type
+ -> TcM (LHsExpr TcId) -- Generalised expr with expected type
tcCheckSigma expr expected_ty
- = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
+ = -- traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
tc_expr' expr expected_ty
tc_expr' expr sigma_ty
= tcGen sigma_ty emptyVarSet (
\ rho_ty -> tcCheckRho expr rho_ty
) `thenM` \ (gen_fn, expr') ->
- returnM (gen_fn <$> expr')
+ returnM (L (getLoc expr') (gen_fn <$> unLoc expr'))
tc_expr' expr rho_ty -- Monomorphic case
= tcCheckRho expr rho_ty
so we must create a hole to pass in as the expected tyvar.
\begin{code}
-tcCheckRho :: RenamedHsExpr -> TcRhoType -> TcM TcExpr
+tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty)
-tcInferRho :: RenamedHsExpr -> TcM (TcExpr, TcRhoType)
-tcInferRho (HsVar name) = tcId name
-tcInferRho expr = newHole `thenM` \ hole ->
- tcMonoExpr expr (Infer hole) `thenM` \ expr' ->
- readMutVar hole `thenM` \ rho_ty ->
- returnM (expr', 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 <$> expr') }
+tcSyntaxOp orig other ty = pprPanic "tcSyntaxOp" (ppr other)
\end{code}
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{The TAUT rules for variables}TcExpr
%* *
%************************************************************************
\begin{code}
-tcMonoExpr :: RenamedHsExpr -- Expession to type check
+tcMonoExpr :: LHsExpr Name -- Expession to type check
-> Expected TcRhoType -- Expected type (could be a type variable)
-- Definitely no foralls at the top
-- Can be a 'hole'.
- -> TcM TcExpr
+ -> TcM (LHsExpr TcId)
+
+tcMonoExpr (L loc expr) res_ty
+ = setSrcSpan loc (do { expr' <- tcExpr expr res_ty
+ ; return (L loc expr') })
-tcMonoExpr (HsVar name) res_ty
- = tcId name `thenM` \ (expr', id_ty) ->
- tcSubExp res_ty id_ty `thenM` \ co_fn ->
- returnM (co_fn <$> 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 <$> expr') }
-tcMonoExpr (HsIPVar ip) res_ty
+tcExpr (HsIPVar ip) res_ty
= -- Implicit parameters must have a *tau-type* not a
-- type scheme. We enforce this by creating a fresh
-- type variable as its type. (Because res_ty may not
-- be a tau-type.)
- newTyVarTy openTypeKind `thenM` \ ip_ty ->
- newIPDict (IPOcc ip) ip ip_ty `thenM` \ (ip', inst) ->
+ newTyFlexiVarTy argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
+ newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
extendLIE inst `thenM_`
tcSubExp res_ty ip_ty `thenM` \ co_fn ->
returnM (co_fn <$> HsIPVar ip')
%************************************************************************
\begin{code}
-tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = addErrCtxt (exprSigCtxt in_expr) $
+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 <$> expr')
+ returnM (co_fn <$> ExprWithTySigOut expr' poly_ty)
-tcMonoExpr (HsType ty) res_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)
%************************************************************************
\begin{code}
-tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty
-tcMonoExpr (HsOverLit lit) res_ty = zapExpectedType res_ty `thenM` \ res_ty' ->
- newOverloadedLit (LiteralOrigin lit) lit res_ty'
-tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
- returnM (HsPar expr')
-tcMonoExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
- returnM (HsSCC lbl expr')
-
-tcMonoExpr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
+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')
-tcMonoExpr (NegApp expr neg_name) res_ty
- = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
- -- ToDo: use tcSyntaxName
-tcMonoExpr (HsLam match) res_ty
+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')
-tcMonoExpr (HsApp e1 e2) res_ty
+tcExpr (HsApp e1 e2) res_ty
= tcApp e1 [e2] res_ty
\end{code}
-- or just
-- op e
-tcMonoExpr in_expr@(SectionL arg1 op) res_ty
+tcExpr in_expr@(SectionL arg1 op) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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 ->
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcMonoExpr in_expr@(SectionR op arg2) res_ty
+tcExpr in_expr@(SectionR op arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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 ->
-- equivalent to (op e1) e2:
-tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty
+tcExpr in_expr@(OpApp arg1 op fix arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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 (OpApp arg1' op' fix arg2')
+ returnM (co_fn <$> OpApp arg1' op' fix arg2')
\end{code}
\begin{code}
-tcMonoExpr (HsLet binds expr) res_ty
- = tcBindsAndThen
- HsLet
- binds -- Bindings to check
- (tcMonoExpr expr res_ty)
+tcExpr (HsLet binds expr) res_ty
+ = do { (binds', expr') <- tcLocalBinds binds $
+ tcMonoExpr expr res_ty
+ ; return (HsLet binds' expr') }
-tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
- = addSrcLoc src_loc $
- addErrCtxt (caseCtxt in_expr) $
-
- -- Typecheck the case alternatives first.
+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
-
- tcMatchesCase matches res_ty `thenM` \ (scrut_ty, matches') ->
-
- addErrCtxt (caseScrutCtxt scrut) (
- tcCheckRho scrut scrut_ty
- ) `thenM` \ scrut' ->
-
- returnM (HsCase scrut' matches' src_loc)
-
-tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
- = addSrcLoc src_loc $
- addErrCtxt (predCtxt pred) (
- tcCheckRho pred boolTy ) `thenM` \ pred' ->
-
- zapExpectedType res_ty `thenM` \ res_ty' ->
+ --
+ -- 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' src_loc)
+ returnM (HsIf pred' b1' b2')
-tcMonoExpr (HsDo do_or_lc stmts method_names _ src_loc) res_ty
- = addSrcLoc src_loc $
- zapExpectedType res_ty `thenM` \ res_ty' ->
- -- All comprehensions yield a monotype
- tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') ->
- returnM (HsDo do_or_lc stmts' methods' res_ty' src_loc)
+tcExpr (HsDo do_or_lc stmts body _) res_ty
+ = tcDoStmts do_or_lc stmts body res_ty
-tcMonoExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
+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')
= addErrCtxt (listCtxt expr) $
tcCheckRho expr elt_ty
-tcMonoExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
- = zapToPArrTy res_ty `thenM` \ elt_ty ->
- mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
- returnM (ExplicitPArr elt_ty exprs')
+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
-
-tcMonoExpr (ExplicitTuple exprs boxity) res_ty
- = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
- tcCheckRhos exprs arg_tys `thenM` \ exprs' ->
- returnM (ExplicitTuple exprs' boxity)
-
-tcMonoExpr (HsProc pat cmd loc) res_ty
- = addSrcLoc loc $
- tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
- returnM (HsProc pat' cmd' loc)
-\end{code}
-
-
-%************************************************************************
-%* *
- Foreign calls
-%* *
-%************************************************************************
+ = addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty)
-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.
+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) }
-\begin{code}
-tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty
-
- = getDOpts `thenM` \ dflags ->
-
- checkTc (not (is_casm && dopt_HscLang dflags /= HscC))
- (vcat [text "_casm_ is only supported when compiling via C (-fvia-C).",
- text "Either compile with -fvia-C, or, better, rewrite your code",
- text "to use the foreign function interface. _casm_s are deprecated",
- text "and support for them may one day disappear."])
- `thenM_`
-
- -- Get the callable and returnable classes.
- tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
- tcLookupClass cReturnableClassName `thenM` \ cReturnableClass ->
- tcLookupTyCon ioTyConName `thenM` \ ioTyCon ->
- let
- new_arg_dict (arg, arg_ty)
- = newDicts (CCallOrigin (unpackFS lbl) (Just arg))
- [mkClassPred cCallableClass [arg_ty]] `thenM` \ arg_dicts ->
- returnM arg_dicts -- Actually a singleton bag
-
- result_origin = CCallOrigin (unpackFS lbl) Nothing {- Not an arg -}
- in
+tcExpr (HsProc pat cmd) res_ty
+ = tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
+ returnM (HsProc pat' cmd')
- -- Arguments
- let tv_idxs | null args = []
- | otherwise = [1..length args]
- in
- newTyVarTys (length tv_idxs) openTypeKind `thenM` \ arg_tys ->
- tcCheckRhos args arg_tys `thenM` \ args' ->
+tcExpr e@(HsArrApp _ _ _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
- -- The argument types can be unlifted or lifted; the result
- -- type must, however, be lifted since it's an argument to the IO
- -- type constructor.
- newTyVarTy liftedTypeKind `thenM` \ result_ty ->
- let
- io_result_ty = mkTyConApp ioTyCon [result_ty]
- in
- zapExpectedTo res_ty io_result_ty `thenM_`
-
- -- Construct the extra insts, which encode the
- -- constraints on the argument and result types.
- mappM new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenM` \ ccarg_dicts_s ->
- newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenM` \ ccres_dict ->
- extendLIEs (ccres_dict ++ concat ccarg_dicts_s) `thenM_`
- returnM (HsCCall lbl args' may_gc is_casm io_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}
-
%************************************************************************
%* *
Record construction and update
%************************************************************************
\begin{code}
-tcMonoExpr expr@(RecordCon con_name rbinds) res_ty
- = addErrCtxt (recordConCtxt expr) $
- tcId con_name `thenM` \ (con_expr, con_tau) ->
- let
- (_, record_ty) = tcSplitFunTys con_tau
- (tycon, ty_args) = tcSplitTyConApp record_ty
- in
- ASSERT( isAlgTyCon tycon )
- zapExpectedTo res_ty record_ty `thenM_`
+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
- -- Check that the record bindings match the constructor
- -- con_name is syntactically constrained to be a data constructor
- tcLookupDataCon con_name `thenM` \ data_con ->
- let
- bad_fields = badFields rbinds data_con
- in
- if notNull bad_fields then
- mappM (addErrTc . badFieldCon data_con) bad_fields `thenM_`
- failM -- Fail now, because tcRecordBinds will crash on a bad field
- else
+ ; let (arg_tys, record_ty) = tcSplitFunTys con_tau
+ flds_w_tys = zipEqual "tcExpr RecordCon" (dataConFieldLabels data_con) arg_tys
+
+ -- Make the result type line up
+ ; zapExpectedTo res_ty record_ty
-- Typecheck the record bindings
- tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' ->
+ ; rbinds' <- tcRecordBinds data_con flds_w_tys rbinds
-- Check for missing fields
- checkMissingFields data_con rbinds `thenM_`
+ ; checkMissingFields data_con rbinds
- returnM (RecordConOut data_con con_expr rbinds')
+ ; returnM (RecordCon (L loc (dataConWrapId data_con)) con_expr rbinds') }
-- The main complication with RecordUpd is that we need to explicitly
-- handle the *non-updated* fields. Consider:
--
-- All this is done in STEP 4 below.
-tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty
+tcExpr expr@(RecordUpd record_expr rbinds _ _) res_ty
= addErrCtxt (recordUpdCtxt expr) $
-- STEP 0
-- Check that the field names are really field names
ASSERT( notNull rbinds )
let
- field_names = recBindFields rbinds
+ field_names = map fst rbinds
in
- mappM tcLookupGlobal_maybe field_names `thenM` \ maybe_sel_ids ->
+ mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids ->
+ -- The renamer has already checked that they
+ -- are all in scope
let
- bad_guys = [ addErrTc (notSelector field_name)
- | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids,
- not (is_selector maybe_sel_id)
+ 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
]
- is_selector (Just (AnId sel_id)) = isRecordSelector sel_id -- Excludes class ops
- is_selector other = False
in
checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_`
-- 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)
- (Just (AnId sel_id) : _) = maybe_sel_ids
- field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if
- tycon = fieldLabelTyCon field_lbl -- it's not a field label
- data_cons = tyConDataCons tycon
- tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
+ sel_id : _ = sel_ids
+ (tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
+ data_cons = tyConDataCons tycon -- it's not a field label
in
- tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
+
+ -- 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 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
- zapExpectedTo res_ty result_record_ty `thenM_`
- tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' ->
+ (badFieldsUpd rbinds) `thenM_`
-- STEP 4
-- Use the un-updated fields to find a vector of booleans saying
-- WARNING: this code assumes that all data_cons in a common tycon
-- have FieldLabels abstracted over the same tyvars.
let
- upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds')
- con_field_lbls_s = map dataConFieldLabels data_cons
+ upd_field_lbls = recBindFields rbinds
-- 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
-
- non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
- common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
+ -- 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 ->
- mk_inst_ty (tyvar, result_inst_ty)
- | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
- | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+ -- 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
- mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys ->
+ zapExpectedTo res_ty result_record_ty `thenM_`
+ tcRecordBinds con1 inst_fld_tys rbinds `thenM` \ rbinds' ->
-- STEP 5
-- Typecheck the expression to be updated
let
- record_ty = mkTyConApp tycon inst_tys
+ 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
tcCheckRho record_expr record_ty `thenM` \ record_expr' ->
-- do pattern matching over the data cons.
--
-- What dictionaries do we need?
- -- We just take the context of the type constructor
+ -- 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 (tyConTheta tycon)
+ theta' = substTheta inst_env (tyConStupidTheta tycon)
in
newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
extendLIEs dicts `thenM_`
-- Phew!
- returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds')
+ returnM (RecordUpd record_expr' rbinds' record_ty result_record_ty)
\end{code}
%************************************************************************
\begin{code}
-tcMonoExpr (ArithSeqIn seq@(From expr)) res_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 (ArithSeqOut (HsVar enum_from) (From expr'))
+ returnM (ArithSeq (HsVar enum_from) (From expr'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+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' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromThenName `thenM` \ enum_from_then ->
- returnM (ArithSeqOut (HsVar enum_from_then) (FromThen expr1' expr2'))
+ returnM (ArithSeq (HsVar enum_from_then) (FromThen expr1' expr2'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+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' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromToName `thenM` \ enum_from_to ->
- returnM (ArithSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (ArithSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+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' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromThenToName `thenM` \ eft ->
- returnM (ArithSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (ArithSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+tcExpr in_expr@(PArrSeq _ seq@(FromTo expr1 expr2)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- zapToPArrTy res_ty `thenM` \ elt_ty ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromToPName `thenM` \ enum_from_to ->
- returnM (PArrSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (PArrSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+tcExpr in_expr@(PArrSeq _ seq@(FromThenTo expr1 expr2 expr3)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- zapToPArrTy res_ty `thenM` \ elt_ty ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromThenToPName `thenM` \ eft ->
- returnM (PArrSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (PArrSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
-tcMonoExpr (PArrSeqIn _) _
+tcExpr (PArrSeq _ _) _
= panic "TcExpr.tcMonoExpr: Infinite parallel array!"
-- the parser shouldn't have generated it and the renamer shouldn't have
-- let it through
\begin{code}
#ifdef GHCI /* Only if bootstrapped */
-- Rename excludes these cases otherwise
-
-tcMonoExpr (HsSplice n expr loc) res_ty = addSrcLoc loc (tcSpliceExpr n expr res_ty)
-tcMonoExpr (HsBracket brack loc) res_ty = addSrcLoc loc (tcBracket brack res_ty)
-
-tcMonoExpr (HsReify (Reify flavour name)) res_ty
- = addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $
- tcMetaTy tycon_name `thenM` \ reify_ty ->
- zapExpectedTo res_ty reify_ty `thenM_`
- returnM (HsReify (ReifyOut flavour name))
- where
- tycon_name = case flavour of
- ReifyDecl -> DsMeta.decQTyConName
- ReifyType -> DsMeta.typeQTyConName
- ReifyFixity -> pprPanic "tcMonoExpr: cant do reifyFixity yet" (ppr name)
+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}
%************************************************************************
\begin{code}
-tcMonoExpr other _ = pprPanic "tcMonoExpr" (ppr other)
+tcExpr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
\begin{code}
-tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
+tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args
-> Expected TcRhoType -- Expected result type of application
- -> TcM TcExpr -- Translated fun and args
+ -> TcM (HsExpr TcId) -- Translated fun and args
-tcApp (HsApp e1 e2) args res_ty
+tcApp (L _ (HsApp e1 e2)) args res_ty
= tcApp e1 (e2:args) res_ty -- Accumulate the arguments
tcApp fun args res_ty
- = -- First type-check the function
- tcInferRho fun `thenM` \ (fun', fun_ty) ->
-
- addErrCtxt (wrongArgsCtxt "too many" fun args) (
- traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_`
- split_fun_ty fun_ty (length args)
- ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
-
- -- Unify with expected result before (was: after) type-checking the args
- -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty).
- -- This is when we might detect a too-few args situation.
- -- (One can think of cases when the opposite order would give
- -- a better error message.)
- -- [March 2003: I'm experimenting with putting this first. Here's an
- -- example where it actually makes a real difference
- -- class C t a b | t a -> b
- -- instance C Char a Bool
- --
- -- data P t a = forall b. (C t a b) => MkP b
- -- data Q t = MkQ (forall a. P t a)
-
- -- f1, f2 :: Q Char;
- -- f1 = MkQ (MkP True)
- -- f2 = MkQ (MkP True :: forall a. P Char a)
- --
- -- With the change, f1 will type-check, because the 'Char' info from
- -- the signature is propagated into MkQ's argument. With the check
- -- in the other order, the extra signature in f2 is reqd.]
-
- addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
- (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
-
- -- Now typecheck the args
- mappM (tcArg fun)
- (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
-
- returnM (co_fn <$> foldl HsApp fun' args')
-
+ = do { let n_args = length args
+ ; (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
+
+ -- Extract its argument types
+ ; (expected_arg_tys, actual_res_ty)
+ <- do { traceTc (text "tcApp" <+> (ppr fun $$ 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)
+-- 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 ~(Check expected_res_ty) actual_res_ty tidy_env
+checkArgsCtxt fun args (Infer _) actual_res_ty tidy_env
+ = return (tidy_env, ptext SLIT("Urk infer"))
+
+checkArgsCtxt fun args (Check expected_res_ty) actual_res_ty tidy_env
= zonkTcType expected_res_ty `thenM` \ exp_ty' ->
zonkTcType actual_res_ty `thenM` \ act_ty' ->
let
in
returnM (env2, message)
-
-split_fun_ty :: TcRhoType -- The type of the function
- -> Int -- Number of arguments
- -> TcM ([TcType], -- Function argument types
- TcType) -- Function result types
-
-split_fun_ty fun_ty 0
- = returnM ([], fun_ty)
-
-split_fun_ty fun_ty n
- = -- Expect the function to have type A->B
- unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) ->
- split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) ->
- returnM (arg_ty:arg_tys, final_res_ty)
-\end{code}
-
-\begin{code}
-tcArg :: RenamedHsExpr -- The function (for error messages)
- -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type
- -> TcM TcExpr -- Resulting argument and LIE
-
-tcArg the_fun (arg, expected_arg_ty, arg_no)
- = addErrCtxt (funAppCtxt the_fun arg arg_no) $
- tcCheckSigma arg expected_arg_ty
+----------------
+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
+ 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}
b) perhaps fewer separated lambdas
\begin{code}
-tcId :: Name -> TcM (TcExpr, TcRhoType)
-tcId name -- Look up the Id and instantiate its type
- = -- First check whether it's a DataCon
- -- Reason: we must not forget to chuck in the
- -- constraints from their "silly context"
- tcLookup name `thenM` \ maybe_thing ->
- case maybe_thing of {
- AGlobal (ADataCon data_con) -> inst_data_con data_con
- ; AGlobal (AnId id) -> loop (HsVar id) (idType id)
+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 proc_level -> tc_local_id id th_level proc_level
- ; other -> pprPanic "tcId" (ppr name)
+ ; ATcId id th_level -> tc_local_id id th_level
+
+ ; other -> failWithTc (ppr other <+> ptext SLIT("used where a value identifer was expected"))
}
where
#ifndef GHCI
- tc_local_id id th_bind_lvl proc_lvl -- Non-TH case
- = checkProcLevel id proc_lvl `thenM_`
- loop (HsVar id) (idType id)
+ tc_local_id id th_bind_lvl -- Non-TH case
+ = instantiate id
#else /* GHCI and TH is on */
- tc_local_id id th_bind_lvl proc_lvl -- TH case
- = checkProcLevel id proc_lvl `thenM_`
-
- -- Check for cross-stage lifting
+ tc_local_id id th_bind_lvl -- TH case
+ = -- Check for cross-stage lifting
getStage `thenM` \ use_stage ->
case use_stage of
Brack use_lvl ps_var lie_var
| use_lvl > th_bind_lvl
- -> -- E.g. \x -> [| h x |]
- -- We must behave as if the reference to x was
-
- -- h $(lift x)
- -- We use 'x' itself as the splice proxy, used by
- -- the desugarer to stitch it all back together.
- -- 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 ((name, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_`
-
- returnM (HsVar id, id_ty))
+ -> 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 $(lift x)
+ -- We use 'x' itself as the splice proxy, used by
+ -- the desugarer to stitch it all back together.
+ -- If 'x' occurs many times we may get many identical
+ -- bindings of the same splice proxy, but that doesn't
+ -- matter, although it's a mite untidy.
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((id_name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
+
+ returnM (HsVar id, [], id_ty))
other ->
checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
- loop (HsVar id) (idType id)
+ instantiate id
#endif /* GHCI */
- loop (HsVar fun_id) fun_ty
+ instantiate :: TcId -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ instantiate fun_id = loop (HsVar fun_id) [] (idType fun_id)
+
+ loop (HsVar fun_id) tvs fun_ty
| want_method_inst fun_ty
- = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ = tcInstType fun_ty `thenM` \ (tyvars, theta, tau) ->
newMethodWithGivenTy orig fun_id
(mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
- loop (HsVar meth_id) tau
+ loop (HsVar meth_id) (tvs ++ tyvars) tau
- loop fun fun_ty
+ loop fun tvs fun_ty
| isSigmaTy fun_ty
- = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
- loop (inst_fn <$> fun) tau
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, new_tvs, tau) ->
+ loop (inst_fn <$> fun) (tvs ++ new_tvs) tau
| otherwise
- = returnM (fun, fun_ty)
+ = returnM (fun, tvs, fun_ty)
-- Hack Alert (want_method_inst)!
-- If f :: (%x :: T) => Int -> Int
| otherwise = case tcSplitSigmaTy fun_ty of
(_,[],_) -> False -- Not overloaded
(_,theta,_) -> not (any isLinearPred theta)
-
-
- -- We treat data constructors differently, because we have to generate
- -- constraints for their silly theta, which no longer appears in
- -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs
- -- It's dual to TcPat.tcConstructor
- inst_data_con data_con
- = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
- extendLIEs ex_dicts `thenM_`
- returnM (mkHsDictApp (mkHsTyApp (HsVar (dataConWrapId data_con)) ty_args)
- (map instToId ex_dicts),
- mkFunTys arg_tys result_ty)
-
- orig = OccurrenceOf name
\end{code}
%************************************************************************
\begin{code}
tcRecordBinds
- :: TyCon -- Type constructor for the record
- -> [TcType] -- Args of this type constructor
- -> RenamedRecordBinds
- -> TcM TcRecordBinds
-
-tcRecordBinds tycon ty_args rbinds
- = mappM do_bind rbinds
+ :: 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
- tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
-
- do_bind (field_lbl_name, rhs)
- = addErrCtxt (fieldCtxt field_lbl_name) $
- tcLookupId field_lbl_name `thenM` \ sel_id ->
- let
- field_lbl = recordSelectorFieldLabel sel_id
- field_ty = substTy tenv (fieldLabelType field_lbl)
- in
- ASSERT( isRecordSelector sel_id )
- -- This lookup and assertion will surely succeed, because
- -- we check that the fields are indeed record selectors
- -- before calling tcRecordBinds
- ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl )
- -- The caller of tcRecordBinds has already checked
- -- that all the fields come from the same type
-
- tcCheckSigma rhs field_ty `thenM` \ rhs' ->
-
- returnM (sel_id, rhs')
+ 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 = map fieldLabelName (dataConFieldLabels data_con)
+ field_names = dataConFieldLabels data_con
-checkMissingFields :: DataCon -> RenamedRecordBinds -> TcM ()
+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
missing_s_fields
= [ fl | (fl, str) <- field_info,
isMarkedStrict str,
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
missing_ns_fields
= [ fl | (fl, str) <- field_info,
not (isMarkedStrict str),
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
field_names_used = recBindFields rbinds
field_labels
field_strs
- field_strs = dropList ex_theta (dataConStrictMarks data_con)
- -- The 'drop' is because dataConStrictMarks
- -- includes the existential dictionaries
- (_, _, _, ex_theta, _, _) = dataConSig data_con
+ field_strs = dataConStrictMarks data_con
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcCheckRhos :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr]
+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 $$ ppr tys)
\end{code}
Overloaded literals.
\begin{code}
-tcLit :: HsLit -> Expected TcRhoType -> TcM TcExpr
-tcLit (HsLitLit s _) res_ty
- = zapExpectedType res_ty `thenM` \ res_ty' ->
- tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
- newDicts (LitLitOrigin (unpackFS s))
- [mkClassPred cCallableClass [res_ty']] `thenM` \ dicts ->
- extendLIEs dicts `thenM_`
- returnM (HsLit (HsLitLit s res_ty'))
-
+tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId)
tcLit lit res_ty
= zapExpectedTo res_ty (hsLitType lit) `thenM_`
returnM (HsLit lit)
caseScrutCtxt expr
= hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-exprSigCtxt expr
- = hang (ptext SLIT("When checking the type signature of the expression:"))
- 4 (ppr expr)
-
exprCtxt expr
= hang (ptext SLIT("In the expression:")) 4 (ppr expr)
appCtxt fun args
= ptext SLIT("In the application") <+> quotes (ppr the_app)
where
- the_app = foldl HsApp fun args -- Used in error messages
-
-lurkingRank2Err fun fun_ty
- = hang (hsep [ptext SLIT("Illegal use of"), quotes (ppr fun)])
- 4 (vcat [ptext SLIT("It is applied to too few arguments"),
- ptext SLIT("so that the result type has for-alls in it:") <+> ppr fun_ty])
+ the_app = foldl mkHsApp fun args -- Used in error messages
+nonVanillaUpd tycon
+ = vcat [ptext SLIT("Record update for the non-Haskell-98 data type") <+> quotes (ppr tycon)
+ <+> ptext SLIT("is not (yet) supported"),
+ ptext SLIT("Use pattern-matching instead")]
badFieldsUpd rbinds
= hang (ptext SLIT("No constructor has all these fields:"))
4 (pprQuotedList (recBindFields rbinds))
recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr
recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr
+naughtyRecordSel sel_id
+ = ptext SLIT("Cannot use record selector") <+> quotes (ppr sel_id) <+>
+ ptext SLIT("as a function due to escaped type variables") $$
+ ptext SLIT("Probably fix: use pattern-matching syntax instead")
+
notSelector field
= hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
= ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:")
<+> pprWithCommas ppr fields
-polySpliceErr :: Id -> SDoc
-polySpliceErr id
- = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
-
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
+ 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}
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