import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
import HsSyn ( HsReify(..), ReifyFlavour(..) )
import TcType ( isTauTy )
-import TcEnv ( bracketOK, tcMetaTy, tcLookupGlobal,
- wellStaged, metaLevel )
+import TcEnv ( bracketOK, tcMetaTy, checkWellStaged, metaLevel )
import TcSimplify ( tcSimplifyBracket )
import Name ( isExternalName )
import qualified DsMeta
tidyOpenType
)
import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector, isDataConWrapId_maybe )
-import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks )
+import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks, dataConWrapId )
import Name ( Name )
-import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
+import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons, isClassTyCon )
import Subst ( mkTopTyVarSubst, substTheta, substTy )
import VarSet ( emptyVarSet, elemVarSet )
import TysWiredIn ( boolTy )
let
bad_guys = [ addErrTc (notSelector field_name)
| (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids,
- case maybe_sel_id of
- Just (AnId sel_id) -> not (isRecordSelector sel_id)
- other -> True
+ not (is_selector maybe_sel_id)
]
+ 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_`
let
-- It's OK to use the non-tc splitters here (for a selector)
(Just (AnId sel_id) : _) = maybe_sel_ids
-
- (_, _, tau) = tcSplitSigmaTy (idType sel_id) -- Selectors can be overloaded
- -- when the data type has a context
- data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector
- tycon = tcTyConAppTyCon data_ty
+ 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
in
-- 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 $
- getStage `thenM` \ level ->
- case bracketOK level of {
- Nothing -> failWithTc (illegalBracket level) ;
- Just next_level ->
-
- -- Typecheck expr to make sure it is valid,
- -- but throw away the results. We'll type check
- -- it again when we actually use it.
- newMutVar [] `thenM` \ pending_splices ->
- getLIEVar `thenM` \ lie_var ->
-
- setStage (Brack next_level pending_splices lie_var) (
- getLIE (tcBracket brack)
- ) `thenM` \ (meta_ty, lie) ->
- tcSimplifyBracket lie `thenM_`
-
- unifyTauTy res_ty meta_ty `thenM_`
-
- -- Return the original expression, not the type-decorated one
- readMutVar pending_splices `thenM` \ pendings ->
- returnM (HsBracketOut brack pendings)
- }
+tcMonoExpr (HsBracket brack loc) res_ty = addSrcLoc loc (tcBracket brack)
tcMonoExpr (HsReify (Reify flavour name)) res_ty
= addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $
\begin{code}
tcId :: Name -> TcM (TcExpr, TcType)
tcId name -- Look up the Id and instantiate its type
- = tcLookupIdLvl name `thenM` \ (id, bind_lvl) ->
+ = -- First check whether it's a DataCon
+ -- Reason: we must not forget to chuck in the
+ -- constraints from their "silly context"
+ tcLookupGlobal_maybe name `thenM` \ maybe_thing ->
+ case maybe_thing of {
+ Just (ADataCon data_con) -> inst_data_con data_con ;
+ other ->
+
+ -- OK, so now look for ordinary Ids
+ tcLookupIdLvl name `thenM` \ (id, bind_lvl) ->
+#ifndef GHCI
+ loop (HsVar id) (idType id) -- Non-TH case
+
+#else /* GHCI is on */
-- Check for cross-stage lifting
-#ifdef GHCI
getStage `thenM` \ use_stage ->
case use_stage of
Brack use_lvl ps_var lie_var
| use_lvl > bind_lvl && not (isExternalName name)
-> -- 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
- -- NB: isExernalName is true of top level things,
- -- and false of nested bindings
+ -- 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.
+ --
+ -- NB: During type-checking, isExernalName is true of
+ -- top level things, and false of nested bindings
+ -- Top-level things don't need lifting.
let
id_ty = idType id
returnM (HsVar id, id_ty))
other ->
- let
- use_lvl = metaLevel use_stage
- in
- checkTc (wellStaged bind_lvl use_lvl)
- (badStageErr id bind_lvl use_lvl) `thenM_`
+ checkWellStaged (quotes (ppr id)) bind_lvl use_stage `thenM_`
+ loop (HsVar id) (idType id)
#endif
- -- This is the bit that handles the no-Template-Haskell case
- case isDataConWrapId_maybe id of
- Nothing -> loop (HsVar id) (idType id)
- Just data_con -> inst_data_con id data_con
+ }
where
orig = OccurrenceOf name
| otherwise
= returnM (fun, fun_ty)
- want_method_inst fun_ty
- | opt_NoMethodSharing = False
- | otherwise = case tcSplitSigmaTy fun_ty of
- (_,[],_) -> False -- Not overloaded
- (_,theta,_) -> not (any isLinearPred theta)
- -- This is a slight hack.
+ -- 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:
-- 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)
+
-- We treat data constructors differently, because we have to generate
-- constraints for their silly theta, which no longer appears in
-- the type of dataConWrapId. It's dual to TcPat.tcConstructor
- inst_data_con id data_con
+ 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 id) ty_args) (map instToId ex_dicts),
+ returnM (mkHsDictApp (mkHsTyApp (HsVar (dataConWrapId data_con)) ty_args)
+ (map instToId ex_dicts),
mkFunTys arg_tys result_ty)
\end{code}
arithSeqCtxt expr
= hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-
-badStageErr id bind_lvl use_lvl
- = ptext SLIT("Stage error:") <+> quotes (ppr id) <+>
- hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
- ptext SLIT("but used at stage") <+> ppr use_lvl]
-
parrSeqCtxt expr
= hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
predCtxt expr
= hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-illegalBracket level
- = ptext SLIT("Illegal bracket at level") <+> ppr level
-
appCtxt fun args
= ptext SLIT("In the application") <+> quotes (ppr the_app)
where
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:")
projects / ghc-hetmet.git / blobdiff