\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 ( nlHsVar )
import Id ( Id )
import Name ( isExternalName )
import TcType ( isTauTy )
#endif
import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
- HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar )
+ HsMatchContext(..), HsRecordBinds, mkHsApp )
import TcHsSyn ( hsLitType, (<$>) )
import TcRnMonad
-import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
+import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo,
+ tcSubExp, tcGen, tcSub,
unifyFunTys, zapToListTy, zapToTyConApp )
import BasicTypes ( isMarkedStrict )
-import Inst ( InstOrigin(..),
- newOverloadedLit, newMethodFromName, newIPDict,
+import Inst ( tcOverloadedLit, newMethodFromName, newIPDict,
newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall )
-import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookup, tcLookupId, checkProcLevel,
+import TcBinds ( tcLocalBinds )
+import TcEnv ( tcLookup, tcLookupId,
tcLookupDataCon, tcLookupGlobalId
)
import TcArrows ( tcProc )
import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
import TcPat ( badFieldCon, refineTyVars )
import TcMType ( tcInstTyVars, tcInstType, newTyFlexiVarTy, zonkTcType )
-import TcType ( Type, TcTyVar, TcType, TcSigmaType, TcRhoType,
- tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
+import TcType ( TcTyVar, TcType, TcSigmaType, TcRhoType,
+ tcSplitFunTys, mkTyVarTys,
isSigmaTy, mkFunTy, mkTyConApp, tyVarsOfTypes, isLinearPred,
tcSplitSigmaTy, tidyOpenType
)
import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
-import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
-import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector, isNaughtyRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks,
+ dataConWrapId, isVanillaDataCon, dataConTyVars, dataConOrigArgTys )
import Name ( Name )
-import TyCon ( TyCon, FieldLabel, tyConTyVars, tyConStupidTheta,
- tyConDataCons, tyConFields )
-import Type ( zipTopTvSubst, substTheta, substTy )
+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
+ 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
-
-#ifdef DEBUG
-import TyCon ( isAlgTyCon )
-#endif
\end{code}
%************************************************************************
-> 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
tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType)
tcInferRho (L loc (HsVar name)) = setSrcSpan loc $ do
- { (e,_,ty) <- tcId name; return (L loc e, ty)}
+ { (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 <$> expr') }
+tcSyntaxOp orig other ty = pprPanic "tcSyntaxOp" (ppr other)
\end{code}
-> TcM (LHsExpr TcId)
tcMonoExpr (L loc expr) res_ty
- = setSrcSpan loc (do { expr' <- tc_expr expr res_ty
+ = setSrcSpan loc (do { expr' <- tcExpr expr res_ty
; return (L loc expr') })
-tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
-tc_expr (HsVar name) res_ty
- = do { (expr', _, id_ty) <- tcId name
+tcExpr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
+tcExpr (HsVar name) res_ty
+ = do { (expr', _, id_ty) <- tcId (OccurrenceOf name) name
; co_fn <- tcSubExp res_ty id_ty
; returnM (co_fn <$> expr') }
-tc_expr (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
%************************************************************************
\begin{code}
-tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty
+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)
-tc_expr (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}
-tc_expr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+tcExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
returnM (HsPar expr')
-tc_expr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+tcExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
returnM (HsSCC lbl expr')
-tc_expr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
+tcExpr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
returnM (HsCoreAnn lbl expr')
-tc_expr (HsLit lit) res_ty = tcLit lit res_ty
+tcExpr (HsLit lit) res_ty = tcLit lit res_ty
-tc_expr (HsOverLit 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
- newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr ->
- returnM (unLoc lit_expr) -- ToDo: nasty unLoc
+ tcOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit' ->
+ returnM (HsOverLit lit')
-tc_expr (NegApp expr neg_name) res_ty
- = tc_expr (HsApp (nlHsVar neg_name) expr) res_ty
- -- ToDo: use tcSyntaxName
+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') }
-tc_expr (HsLam match) res_ty
+tcExpr (HsLam match) res_ty
= tcMatchLambda match res_ty `thenM` \ match' ->
returnM (HsLam match')
-tc_expr (HsApp e1 e2) res_ty
+tcExpr (HsApp e1 e2) res_ty
= tcApp e1 [e2] res_ty
\end{code}
-- or just
-- op e
-tc_expr in_expr@(SectionL arg1 op) res_ty
+tcExpr in_expr@(SectionL arg1 op) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- unifyFunTys 2 op_ty {- 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
-tc_expr in_expr@(SectionR op arg2) res_ty
+tcExpr in_expr@(SectionR op arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- unifyFunTys 2 op_ty {- 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:
-tc_expr 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) ->
- unifyFunTys 2 op_ty {- 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}
-tc_expr (HsLet binds (L loc expr)) res_ty
- = tcBindsAndThen
- glue
- binds -- Bindings to check
- (setSrcSpan loc $ tc_expr expr res_ty)
- where
- glue bind expr = HsLet [bind] (L loc expr)
+tcExpr (HsLet binds expr) res_ty
+ = do { (binds', expr') <- tcLocalBinds binds $
+ tcMonoExpr expr res_ty
+ ; return (HsLet binds' expr') }
-tc_expr in_expr@(HsCase scrut matches) exp_ty
+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
match_ctxt = MC { mc_what = CaseAlt,
mc_body = tcMonoExpr }
-tc_expr (HsIf pred b1 b2) res_ty
- = addErrCtxt (predCtxt pred) (
- tcCheckRho pred boolTy ) `thenM` \ pred' ->
+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 b2 res_ty' `thenM` \ b2' ->
returnM (HsIf pred' b1' b2')
-tc_expr (HsDo do_or_lc stmts method_names _) res_ty
- = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
- -- All comprehensions yield a monotype of kind *
- tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') ->
- returnM (HsDo do_or_lc stmts' methods' res_ty')
+tcExpr (HsDo do_or_lc stmts body _) res_ty
+ = tcDoStmts do_or_lc stmts body res_ty
-tc_expr 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
-tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+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') }
tc_elt elt_ty expr
= addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty)
-tc_expr (ExplicitTuple exprs boxity) res_ty
+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) }
-tc_expr (HsProc pat cmd) res_ty
+tcExpr (HsProc pat cmd) res_ty
= tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
returnM (HsProc pat' cmd')
-tc_expr e@(HsArrApp _ _ _ _ _) _
+tcExpr e@(HsArrApp _ _ _ _ _) _
= failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
ptext SLIT("was found where an expression was expected")])
-tc_expr e@(HsArrForm _ _ _) _
+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}
-tc_expr expr@(RecordCon con@(L loc con_name) rbinds) res_ty
- = addErrCtxt (recordConCtxt expr) $
- addLocM tcId con `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 (L loc 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.
-tc_expr expr@(RecordUpd record_expr rbinds) res_ty
+tcExpr expr@(RecordUpd record_expr rbinds _ _) res_ty
= addErrCtxt (recordUpdCtxt expr) $
-- STEP 0
sel_id : _ = sel_ids
(tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
data_cons = tyConDataCons tycon -- it's not a field label
- tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars 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
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' ->
-
-- 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.
-- have FieldLabels abstracted over the same tyvars.
let
upd_field_lbls = recBindFields rbinds
- con_field_lbls_s = map dataConFieldLabels data_cons
-- 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 [ty | (fld,ty,_) <- tyConFields tycon,
- fld `elem` non_upd_field_lbls]
-
- mk_inst_ty tyvar result_inst_ty
- | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
--- gaw 2004 FIX?
- | otherwise = newTyFlexiVarTy liftedTypeKind -- Fresh type
+ -- 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 ->
+
+ -- 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
- zipWithM mk_inst_ty 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 (tyConStupidTheta tycon)
in
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}
-tc_expr (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 (nlHsVar enum_from) (From expr'))
+ returnM (ArithSeq (HsVar enum_from) (From expr'))
-tc_expr 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 (nlHsVar enum_from_then) (FromThen expr1' expr2'))
+ returnM (ArithSeq (HsVar enum_from_then) (FromThen expr1' expr2'))
-tc_expr 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 (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (ArithSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
-tc_expr 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 (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (ArithSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
-tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+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' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromToPName `thenM` \ enum_from_to ->
- returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (PArrSeq (HsVar enum_from_to) (FromTo expr1' expr2'))
-tc_expr 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) $
zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromThenToPName `thenM` \ eft ->
- returnM (PArrSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (PArrSeq (HsVar eft) (FromThenTo expr1' expr2' expr3'))
-tc_expr (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
-tc_expr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty
-tc_expr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty
+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}
-tc_expr other _ = pprPanic "tcMonoExpr" (ppr other)
+tcExpr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
= tcApp e1 (e2:args) res_ty -- Accumulate the arguments
tcApp fun args res_ty
- = do { (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
+ = 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)
- <- addErrCtxt (wrongArgsCtxt "too many" fun args) $ do
- { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau))
- ; unifyFunTys (length args) fun_tau }
-
+ <- do { traceTc (text "tcApp" <+> (ppr fun $$ 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
-- 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 f
+ { (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) }
| 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
+ 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 (HsExpr TcId, [TcTyVar], TcRhoType)
+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 id_name -- Look up the Id and instantiate 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
-- 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
- -> do { checkProcLevel id proc_level
- ; tc_local_id id th_level }
+ ; ATcId id th_level -> tc_local_id id th_level
- ; other -> pprPanic "tcId" (ppr id_name $$ ppr thing)
+ ; other -> failWithTc (ppr other <+> ptext SLIT("used where a value identifer was expected"))
}
where
| otherwise = case tcSplitSigmaTy fun_ty of
(_,[],_) -> False -- Not overloaded
(_,theta,_) -> not (any isLinearPred theta)
-
- orig = OccurrenceOf id_name
\end{code}
%************************************************************************
\begin{code}
tcRecordBinds
- :: TyCon -- Type constructor for the record
- -> [TcType] -- Args of this type constructor
+ :: DataCon
+ -> [(FieldLabel,TcType)] -- Expected type for each field
-> HsRecordBinds Name
-> TcM (HsRecordBinds TcId)
-tcRecordBinds tycon ty_args rbinds
- = mappM do_bind rbinds
+tcRecordBinds data_con flds_w_tys rbinds
+ = do { mb_binds <- mappM do_bind rbinds
+ ; return (catMaybes mb_binds) }
where
- tenv = zipTopTvSubst (tyConTyVars tycon) ty_args
-
do_bind (L loc field_lbl, rhs)
+ | Just field_ty <- assocMaybe flds_w_tys field_lbl
= addErrCtxt (fieldCtxt field_lbl) $
- let
- field_ty = tyConFieldType tycon field_lbl
- field_ty' = substTy tenv field_ty
- in
- tcCheckSigma rhs field_ty' `thenM` \ rhs' ->
- tcLookupId field_lbl `thenM` \ sel_id ->
- ASSERT( isRecordSelector sel_id )
- returnM (L loc sel_id, rhs')
-
-tyConFieldType :: TyCon -> FieldLabel -> Type
-tyConFieldType tycon field_lbl
- = case [ty | (f,ty,_) <- tyConFields tycon, f == field_lbl] of
- (ty:other) -> ASSERT( null other) ty
- -- This lookup and assertion will surely succeed, because
- -- we check that the fields are indeed record selectors
- -- before calling tcRecordBinds
+ 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)
= tcCheckRho expr ty `thenM` \ expr' ->
tcCheckRhos exprs tys `thenM` \ exprs' ->
returnM (expr':exprs')
+tcCheckRhos exprs tys = pprPanic "tcCheckRhos" (ppr exprs $$ ppr tys)
\end{code}
where
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")]
projects / ghc-hetmet.git / blobdiff