{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 TcSplice: Template Haskell splices -} {-# LANGUAGE CPP #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE MagicHash #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE InstanceSigs #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RecordWildCards #-} {-# LANGUAGE MultiWayIf #-} {-# LANGUAGE TypeFamilies #-} {-# OPTIONS_GHC -fno-warn-orphans #-} module TcSplice( tcSpliceExpr, tcTypedBracket, tcUntypedBracket, -- runQuasiQuoteExpr, runQuasiQuotePat, -- runQuasiQuoteDecl, runQuasiQuoteType, runAnnotation, runMetaE, runMetaP, runMetaT, runMetaD, runQuasi, tcTopSpliceExpr, lookupThName_maybe, defaultRunMeta, runMeta', runRemoteModFinalizers, finishTH ) where #include "HsVersions.h" import GhcPrelude import HsSyn import Annotations import Finder import Name import TcRnMonad import TcType import Outputable import TcExpr import SrcLoc import THNames import TcUnify import TcEnv import FileCleanup ( newTempName, TempFileLifetime(..) ) import Control.Monad import GHCi.Message import GHCi.RemoteTypes import GHCi import HscMain -- These imports are the reason that TcSplice -- is very high up the module hierarchy import FV import RnSplice( traceSplice, SpliceInfo(..) ) import RdrName import HscTypes import Convert import RnExpr import RnEnv import RnUtils ( HsDocContext(..) ) import RnFixity ( lookupFixityRn_help ) import RnTypes import TcHsSyn import TcSimplify import Type import NameSet import TcMType import TcHsType import TcIface import TyCoRep import FamInst import FamInstEnv import InstEnv import Inst import NameEnv import PrelNames import TysWiredIn import OccName import Hooks import Var import Module import LoadIface import Class import TyCon import CoAxiom import PatSyn import ConLike import DataCon import TcEvidence( TcEvBinds(..) ) import Id import IdInfo import DsExpr import DsMonad import GHC.Serialized import ErrUtils import Util import Unique import VarSet import Data.List ( find ) import Data.Maybe import FastString import BasicTypes hiding( SuccessFlag(..) ) import Maybes( MaybeErr(..) ) import DynFlags import Panic import Lexeme import qualified EnumSet import Plugins import Bag import qualified Language.Haskell.TH as TH -- THSyntax gives access to internal functions and data types import qualified Language.Haskell.TH.Syntax as TH -- Because GHC.Desugar might not be in the base library of the bootstrapping compiler import GHC.Desugar ( AnnotationWrapper(..) ) import Control.Exception import Data.Binary import Data.Binary.Get import qualified Data.ByteString as B import qualified Data.ByteString.Lazy as LB import Data.Dynamic ( fromDynamic, toDyn ) import qualified Data.Map as Map import Data.Typeable ( typeOf, Typeable, TypeRep, typeRep ) import Data.Data (Data) import Data.Proxy ( Proxy (..) ) import GHC.Exts ( unsafeCoerce# ) {- ************************************************************************ * * \subsection{Main interface + stubs for the non-GHCI case * * ************************************************************************ -} tcTypedBracket :: HsExpr GhcRn -> HsBracket GhcRn -> ExpRhoType -> TcM (HsExpr GhcTcId) tcUntypedBracket :: HsExpr GhcRn -> HsBracket GhcRn -> [PendingRnSplice] -> ExpRhoType -> TcM (HsExpr GhcTcId) tcSpliceExpr :: HsSplice GhcRn -> ExpRhoType -> TcM (HsExpr GhcTcId) -- None of these functions add constraints to the LIE -- runQuasiQuoteExpr :: HsQuasiQuote RdrName -> RnM (LHsExpr RdrName) -- runQuasiQuotePat :: HsQuasiQuote RdrName -> RnM (LPat RdrName) -- runQuasiQuoteType :: HsQuasiQuote RdrName -> RnM (LHsType RdrName) -- runQuasiQuoteDecl :: HsQuasiQuote RdrName -> RnM [LHsDecl RdrName] runAnnotation :: CoreAnnTarget -> LHsExpr GhcRn -> TcM Annotation {- ************************************************************************ * * \subsection{Quoting an expression} * * ************************************************************************ -} -- See Note [How brackets and nested splices are handled] -- tcTypedBracket :: HsBracket Name -> TcRhoType -> TcM (HsExpr TcId) tcTypedBracket rn_expr brack@(TExpBr _ expr) res_ty = addErrCtxt (quotationCtxtDoc brack) $ do { cur_stage <- getStage ; ps_ref <- newMutVar [] ; lie_var <- getConstraintVar -- Any constraints arising from nested splices -- should get thrown into the constraint set -- from outside the bracket -- Typecheck expr to make sure it is valid, -- Throw away the typechecked expression but return its type. -- We'll typecheck it again when we splice it in somewhere ; (_tc_expr, expr_ty) <- setStage (Brack cur_stage (TcPending ps_ref lie_var)) $ tcInferRhoNC expr -- NC for no context; tcBracket does that ; meta_ty <- tcTExpTy expr_ty ; ps' <- readMutVar ps_ref ; texpco <- tcLookupId unsafeTExpCoerceName ; tcWrapResultO (Shouldn'tHappenOrigin "TExpBr") rn_expr (unLoc (mkHsApp (nlHsTyApp texpco [expr_ty]) (noLoc (HsTcBracketOut noExt brack ps')))) meta_ty res_ty } tcTypedBracket _ other_brack _ = pprPanic "tcTypedBracket" (ppr other_brack) -- tcUntypedBracket :: HsBracket Name -> [PendingRnSplice] -> ExpRhoType -> TcM (HsExpr TcId) tcUntypedBracket rn_expr brack ps res_ty = do { traceTc "tc_bracket untyped" (ppr brack $$ ppr ps) ; ps' <- mapM tcPendingSplice ps ; meta_ty <- tcBrackTy brack ; traceTc "tc_bracket done untyped" (ppr meta_ty) ; tcWrapResultO (Shouldn'tHappenOrigin "untyped bracket") rn_expr (HsTcBracketOut noExt brack ps') meta_ty res_ty } --------------- tcBrackTy :: HsBracket GhcRn -> TcM TcType tcBrackTy (VarBr {}) = tcMetaTy nameTyConName -- Result type is Var (not Q-monadic) tcBrackTy (ExpBr {}) = tcMetaTy expQTyConName -- Result type is ExpQ (= Q Exp) tcBrackTy (TypBr {}) = tcMetaTy typeQTyConName -- Result type is Type (= Q Typ) tcBrackTy (DecBrG {}) = tcMetaTy decsQTyConName -- Result type is Q [Dec] tcBrackTy (PatBr {}) = tcMetaTy patQTyConName -- Result type is PatQ (= Q Pat) tcBrackTy (DecBrL {}) = panic "tcBrackTy: Unexpected DecBrL" tcBrackTy (TExpBr {}) = panic "tcUntypedBracket: Unexpected TExpBr" tcBrackTy (XBracket {}) = panic "tcUntypedBracket: Unexpected XBracket" --------------- tcPendingSplice :: PendingRnSplice -> TcM PendingTcSplice tcPendingSplice (PendingRnSplice flavour splice_name expr) = do { res_ty <- tcMetaTy meta_ty_name ; expr' <- tcMonoExpr expr (mkCheckExpType res_ty) ; return (PendingTcSplice splice_name expr') } where meta_ty_name = case flavour of UntypedExpSplice -> expQTyConName UntypedPatSplice -> patQTyConName UntypedTypeSplice -> typeQTyConName UntypedDeclSplice -> decsQTyConName --------------- -- Takes a tau and returns the type Q (TExp tau) tcTExpTy :: TcType -> TcM TcType tcTExpTy exp_ty = do { unless (isTauTy exp_ty) $ addErr (err_msg exp_ty) ; q <- tcLookupTyCon qTyConName ; texp <- tcLookupTyCon tExpTyConName ; return (mkTyConApp q [mkTyConApp texp [exp_ty]]) } where err_msg ty = vcat [ text "Illegal polytype:" <+> ppr ty , text "The type of a Typed Template Haskell expression must" <+> text "not have any quantification." ] quotationCtxtDoc :: HsBracket GhcRn -> SDoc quotationCtxtDoc br_body = hang (text "In the Template Haskell quotation") 2 (ppr br_body) -- The whole of the rest of the file is the else-branch (ie stage2 only) {- Note [How top-level splices are handled] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Top-level splices (those not inside a [| .. |] quotation bracket) are handled very straightforwardly: 1. tcTopSpliceExpr: typecheck the body e of the splice $(e) 2. runMetaT: desugar, compile, run it, and convert result back to HsSyn RdrName (of the appropriate flavour, eg HsType RdrName, HsExpr RdrName etc) 3. treat the result as if that's what you saw in the first place e.g for HsType, rename and kind-check for HsExpr, rename and type-check (The last step is different for decls, because they can *only* be top-level: we return the result of step 2.) Note [How brackets and nested splices are handled] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Nested splices (those inside a [| .. |] quotation bracket), are treated quite differently. Remember, there are two forms of bracket typed [|| e ||] and untyped [| e |] The life cycle of a typed bracket: * Starts as HsBracket * When renaming: * Set the ThStage to (Brack s RnPendingTyped) * Rename the body * Result is still a HsBracket * When typechecking: * Set the ThStage to (Brack s (TcPending ps_var lie_var)) * Typecheck the body, and throw away the elaborated result * Nested splices (which must be typed) are typechecked, and the results accumulated in ps_var; their constraints accumulate in lie_var * Result is a HsTcBracketOut rn_brack pending_splices where rn_brack is the incoming renamed bracket The life cycle of a un-typed bracket: * Starts as HsBracket * When renaming: * Set the ThStage to (Brack s (RnPendingUntyped ps_var)) * Rename the body * Nested splices (which must be untyped) are renamed, and the results accumulated in ps_var * Result is still (HsRnBracketOut rn_body pending_splices) * When typechecking a HsRnBracketOut * Typecheck the pending_splices individually * Ignore the body of the bracket; just check that the context expects a bracket of that type (e.g. a [p| pat |] bracket should be in a context needing a (Q Pat) * Result is a HsTcBracketOut rn_brack pending_splices where rn_brack is the incoming renamed bracket In both cases, desugaring happens like this: * HsTcBracketOut is desugared by DsMeta.dsBracket. It a) Extends the ds_meta environment with the PendingSplices attached to the bracket b) Converts the quoted (HsExpr Name) to a CoreExpr that, when run, will produce a suitable TH expression/type/decl. This is why we leave the *renamed* expression attached to the bracket: the quoted expression should not be decorated with all the goop added by the type checker * Each splice carries a unique Name, called a "splice point", thus ${n}(e). The name is initialised to an (Unqual "splice") when the splice is created; the renamer gives it a unique. * When DsMeta (used to desugar the body of the bracket) comes across a splice, it looks up the splice's Name, n, in the ds_meta envt, to find an (HsExpr Id) that should be substituted for the splice; it just desugars it to get a CoreExpr (DsMeta.repSplice). Example: Source: f = [| Just $(g 3) |] The [| |] part is a HsBracket Typechecked: f = [| Just ${s7}(g 3) |]{s7 = g Int 3} The [| |] part is a HsBracketOut, containing *renamed* (not typechecked) expression The "s7" is the "splice point"; the (g Int 3) part is a typechecked expression Desugared: f = do { s7 <- g Int 3 ; return (ConE "Data.Maybe.Just" s7) } Note [Template Haskell state diagram] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here are the ThStages, s, their corresponding level numbers (the result of (thLevel s)), and their state transitions. The top level of the program is stage Comp: Start here | V ----------- $ ------------ $ | Comp | ---------> | Splice | -----| | 1 | | 0 | <----| ----------- ------------ ^ | ^ | $ | | [||] $ | | [||] | v | v -------------- ---------------- | Brack Comp | | Brack Splice | | 2 | | 1 | -------------- ---------------- * Normal top-level declarations start in state Comp (which has level 1). Annotations start in state Splice, since they are treated very like a splice (only without a '$') * Code compiled in state Splice (and only such code) will be *run at compile time*, with the result replacing the splice * The original paper used level -1 instead of 0, etc. * The original paper did not allow a splice within a splice, but there is no reason not to. This is the $ transition in the top right. Note [Template Haskell levels] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * Imported things are impLevel (= 0) * However things at level 0 are not *necessarily* imported. eg $( \b -> ... ) here b is bound at level 0 * In GHCi, variables bound by a previous command are treated as impLevel, because we have bytecode for them. * Variables are bound at the "current level" * The current level starts off at outerLevel (= 1) * The level is decremented by splicing $(..) incremented by brackets [| |] incremented by name-quoting 'f When a variable is used, we compare bind: binding level, and use: current level at usage site Generally bind > use Always error (bound later than used) [| \x -> $(f x) |] bind = use Always OK (bound same stage as used) [| \x -> $(f [| x |]) |] bind < use Inside brackets, it depends Inside splice, OK Inside neither, OK For (bind < use) inside brackets, there are three cases: - Imported things OK f = [| map |] - Top-level things OK g = [| f |] - Non-top-level Only if there is a liftable instance h = \(x:Int) -> [| x |] To track top-level-ness we use the ThBindEnv in TcLclEnv For example: f = ... g1 = $(map ...) is OK g2 = $(f ...) is not OK; because we havn't compiled f yet -} {- ************************************************************************ * * \subsection{Splicing an expression} * * ************************************************************************ -} tcSpliceExpr splice@(HsTypedSplice _ _ name expr) res_ty = addErrCtxt (spliceCtxtDoc splice) $ setSrcSpan (getLoc expr) $ do { stage <- getStage ; case stage of Splice {} -> tcTopSplice expr res_ty Brack pop_stage pend -> tcNestedSplice pop_stage pend name expr res_ty RunSplice _ -> -- See Note [RunSplice ThLevel] in "TcRnTypes". pprPanic ("tcSpliceExpr: attempted to typecheck a splice when " ++ "running another splice") (ppr splice) Comp -> tcTopSplice expr res_ty } tcSpliceExpr splice _ = pprPanic "tcSpliceExpr" (ppr splice) {- Note [Collecting modFinalizers in typed splices] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'qAddModFinalizer' of the @Quasi TcM@ instance adds finalizers in the local environment (see Note [Delaying modFinalizers in untyped splices] in "RnSplice"). Thus after executing the splice, we move the finalizers to the finalizer list in the global environment and set them to use the current local environment (with 'addModFinalizersWithLclEnv'). -} tcNestedSplice :: ThStage -> PendingStuff -> Name -> LHsExpr GhcRn -> ExpRhoType -> TcM (HsExpr GhcTc) -- See Note [How brackets and nested splices are handled] -- A splice inside brackets tcNestedSplice pop_stage (TcPending ps_var lie_var) splice_name expr res_ty = do { res_ty <- expTypeToType res_ty ; meta_exp_ty <- tcTExpTy res_ty ; expr' <- setStage pop_stage $ setConstraintVar lie_var $ tcMonoExpr expr (mkCheckExpType meta_exp_ty) ; untypeq <- tcLookupId unTypeQName ; let expr'' = mkHsApp (nlHsTyApp untypeq [res_ty]) expr' ; ps <- readMutVar ps_var ; writeMutVar ps_var (PendingTcSplice splice_name expr'' : ps) -- The returned expression is ignored; it's in the pending splices ; return (panic "tcSpliceExpr") } tcNestedSplice _ _ splice_name _ _ = pprPanic "tcNestedSplice: rename stage found" (ppr splice_name) tcTopSplice :: LHsExpr GhcRn -> ExpRhoType -> TcM (HsExpr GhcTc) tcTopSplice expr res_ty = do { -- Typecheck the expression, -- making sure it has type Q (T res_ty) res_ty <- expTypeToType res_ty ; meta_exp_ty <- tcTExpTy res_ty ; zonked_q_expr <- tcTopSpliceExpr Typed $ tcMonoExpr expr (mkCheckExpType meta_exp_ty) -- See Note [Collecting modFinalizers in typed splices]. ; modfinalizers_ref <- newTcRef [] -- Run the expression ; expr2 <- setStage (RunSplice modfinalizers_ref) $ runMetaE zonked_q_expr ; mod_finalizers <- readTcRef modfinalizers_ref ; addModFinalizersWithLclEnv $ ThModFinalizers mod_finalizers ; traceSplice (SpliceInfo { spliceDescription = "expression" , spliceIsDecl = False , spliceSource = Just expr , spliceGenerated = ppr expr2 }) -- Rename and typecheck the spliced-in expression, -- making sure it has type res_ty -- These steps should never fail; this is a *typed* splice ; addErrCtxt (spliceResultDoc expr) $ do { (exp3, _fvs) <- rnLExpr expr2 ; exp4 <- tcMonoExpr exp3 (mkCheckExpType res_ty) ; return (unLoc exp4) } } {- ************************************************************************ * * \subsection{Error messages} * * ************************************************************************ -} spliceCtxtDoc :: HsSplice GhcRn -> SDoc spliceCtxtDoc splice = hang (text "In the Template Haskell splice") 2 (pprSplice splice) spliceResultDoc :: LHsExpr GhcRn -> SDoc spliceResultDoc expr = sep [ text "In the result of the splice:" , nest 2 (char '$' <> ppr expr) , text "To see what the splice expanded to, use -ddump-splices"] ------------------- tcTopSpliceExpr :: SpliceType -> TcM (LHsExpr GhcTc) -> TcM (LHsExpr GhcTc) -- Note [How top-level splices are handled] -- Type check an expression that is the body of a top-level splice -- (the caller will compile and run it) -- Note that set the level to Splice, regardless of the original level, -- before typechecking the expression. For example: -- f x = $( ...$(g 3) ... ) -- The recursive call to tcPolyExpr will simply expand the -- inner escape before dealing with the outer one tcTopSpliceExpr isTypedSplice tc_action = checkNoErrs $ -- checkNoErrs: must not try to run the thing -- if the type checker fails! unsetGOptM Opt_DeferTypeErrors $ -- Don't defer type errors. Not only are we -- going to run this code, but we do an unsafe -- coerce, so we get a seg-fault if, say we -- splice a type into a place where an expression -- is expected (Trac #7276) setStage (Splice isTypedSplice) $ do { -- Typecheck the expression (expr', wanted) <- captureConstraints tc_action ; const_binds <- simplifyTop wanted -- Zonk it and tie the knot of dictionary bindings ; zonkTopLExpr (mkHsDictLet (EvBinds const_binds) expr') } {- ************************************************************************ * * Annotations * * ************************************************************************ -} runAnnotation target expr = do -- Find the classes we want instances for in order to call toAnnotationWrapper loc <- getSrcSpanM data_class <- tcLookupClass dataClassName to_annotation_wrapper_id <- tcLookupId toAnnotationWrapperName -- Check the instances we require live in another module (we want to execute it..) -- and check identifiers live in other modules using TH stage checks. tcSimplifyStagedExpr -- also resolves the LIE constraints to detect e.g. instance ambiguity zonked_wrapped_expr' <- tcTopSpliceExpr Untyped $ do { (expr', expr_ty) <- tcInferRhoNC expr -- We manually wrap the typechecked expression in a call to toAnnotationWrapper -- By instantiating the call >here< it gets registered in the -- LIE consulted by tcTopSpliceExpr -- and hence ensures the appropriate dictionary is bound by const_binds ; wrapper <- instCall AnnOrigin [expr_ty] [mkClassPred data_class [expr_ty]] ; let specialised_to_annotation_wrapper_expr = L loc (mkHsWrap wrapper (HsVar noExt (L loc to_annotation_wrapper_id))) ; return (L loc (HsApp noExt specialised_to_annotation_wrapper_expr expr')) } -- Run the appropriately wrapped expression to get the value of -- the annotation and its dictionaries. The return value is of -- type AnnotationWrapper by construction, so this conversion is -- safe serialized <- runMetaAW zonked_wrapped_expr' return Annotation { ann_target = target, ann_value = serialized } convertAnnotationWrapper :: ForeignHValue -> TcM (Either MsgDoc Serialized) convertAnnotationWrapper fhv = do dflags <- getDynFlags if gopt Opt_ExternalInterpreter dflags then do Right <$> runTH THAnnWrapper fhv else do annotation_wrapper <- liftIO $ wormhole dflags fhv return $ Right $ case unsafeCoerce# annotation_wrapper of AnnotationWrapper value | let serialized = toSerialized serializeWithData value -> -- Got the value and dictionaries: build the serialized value and -- call it a day. We ensure that we seq the entire serialized value -- in order that any errors in the user-written code for the -- annotation are exposed at this point. This is also why we are -- doing all this stuff inside the context of runMeta: it has the -- facilities to deal with user error in a meta-level expression seqSerialized serialized `seq` serialized -- | Force the contents of the Serialized value so weknow it doesn't contain any bottoms seqSerialized :: Serialized -> () seqSerialized (Serialized the_type bytes) = the_type `seq` bytes `seqList` () {- ************************************************************************ * * \subsection{Running an expression} * * ************************************************************************ -} runQuasi :: TH.Q a -> TcM a runQuasi act = TH.runQ act runRemoteModFinalizers :: ThModFinalizers -> TcM () runRemoteModFinalizers (ThModFinalizers finRefs) = do dflags <- getDynFlags let withForeignRefs [] f = f [] withForeignRefs (x : xs) f = withForeignRef x $ \r -> withForeignRefs xs $ \rs -> f (r : rs) if gopt Opt_ExternalInterpreter dflags then do hsc_env <- env_top <$> getEnv withIServ hsc_env $ \i -> do tcg <- getGblEnv th_state <- readTcRef (tcg_th_remote_state tcg) case th_state of Nothing -> return () -- TH was not started, nothing to do Just fhv -> do liftIO $ withForeignRef fhv $ \st -> withForeignRefs finRefs $ \qrefs -> writeIServ i (putMessage (RunModFinalizers st qrefs)) () <- runRemoteTH i [] readQResult i else do qs <- liftIO (withForeignRefs finRefs $ mapM localRef) runQuasi $ sequence_ qs runQResult :: (a -> String) -> (SrcSpan -> a -> b) -> (ForeignHValue -> TcM a) -> SrcSpan -> ForeignHValue {- TH.Q a -} -> TcM b runQResult show_th f runQ expr_span hval = do { th_result <- runQ hval ; traceTc "Got TH result:" (text (show_th th_result)) ; return (f expr_span th_result) } ----------------- runMeta :: (MetaHook TcM -> LHsExpr GhcTc -> TcM hs_syn) -> LHsExpr GhcTc -> TcM hs_syn runMeta unwrap e = do { h <- getHooked runMetaHook defaultRunMeta ; unwrap h e } defaultRunMeta :: MetaHook TcM defaultRunMeta (MetaE r) = fmap r . runMeta' True ppr (runQResult TH.pprint convertToHsExpr runTHExp) defaultRunMeta (MetaP r) = fmap r . runMeta' True ppr (runQResult TH.pprint convertToPat runTHPat) defaultRunMeta (MetaT r) = fmap r . runMeta' True ppr (runQResult TH.pprint convertToHsType runTHType) defaultRunMeta (MetaD r) = fmap r . runMeta' True ppr (runQResult TH.pprint convertToHsDecls runTHDec) defaultRunMeta (MetaAW r) = fmap r . runMeta' False (const empty) (const convertAnnotationWrapper) -- We turn off showing the code in meta-level exceptions because doing so exposes -- the toAnnotationWrapper function that we slap around the user's code ---------------- runMetaAW :: LHsExpr GhcTc -- Of type AnnotationWrapper -> TcM Serialized runMetaAW = runMeta metaRequestAW runMetaE :: LHsExpr GhcTc -- Of type (Q Exp) -> TcM (LHsExpr GhcPs) runMetaE = runMeta metaRequestE runMetaP :: LHsExpr GhcTc -- Of type (Q Pat) -> TcM (LPat GhcPs) runMetaP = runMeta metaRequestP runMetaT :: LHsExpr GhcTc -- Of type (Q Type) -> TcM (LHsType GhcPs) runMetaT = runMeta metaRequestT runMetaD :: LHsExpr GhcTc -- Of type Q [Dec] -> TcM [LHsDecl GhcPs] runMetaD = runMeta metaRequestD --------------- runMeta' :: Bool -- Whether code should be printed in the exception message -> (hs_syn -> SDoc) -- how to print the code -> (SrcSpan -> ForeignHValue -> TcM (Either MsgDoc hs_syn)) -- How to run x -> LHsExpr GhcTc -- Of type x; typically x = Q TH.Exp, or -- something like that -> TcM hs_syn -- Of type t runMeta' show_code ppr_hs run_and_convert expr = do { traceTc "About to run" (ppr expr) ; recordThSpliceUse -- seems to be the best place to do this, -- we catch all kinds of splices and annotations. -- Check that we've had no errors of any sort so far. -- For example, if we found an error in an earlier defn f, but -- recovered giving it type f :: forall a.a, it'd be very dodgy -- to carry ont. Mind you, the staging restrictions mean we won't -- actually run f, but it still seems wrong. And, more concretely, -- see Trac #5358 for an example that fell over when trying to -- reify a function with a "?" kind in it. (These don't occur -- in type-correct programs. ; failIfErrsM -- run plugins ; hsc_env <- getTopEnv ; expr' <- withPlugins (hsc_dflags hsc_env) spliceRunAction expr -- Desugar ; ds_expr <- initDsTc (dsLExpr expr') -- Compile and link it; might fail if linking fails ; src_span <- getSrcSpanM ; traceTc "About to run (desugared)" (ppr ds_expr) ; either_hval <- tryM $ liftIO $ HscMain.hscCompileCoreExpr hsc_env src_span ds_expr ; case either_hval of { Left exn -> fail_with_exn "compile and link" exn ; Right hval -> do { -- Coerce it to Q t, and run it -- Running might fail if it throws an exception of any kind (hence tryAllM) -- including, say, a pattern-match exception in the code we are running -- -- We also do the TH -> HS syntax conversion inside the same -- exception-cacthing thing so that if there are any lurking -- exceptions in the data structure returned by hval, we'll -- encounter them inside the try -- -- See Note [Exceptions in TH] let expr_span = getLoc expr ; either_tval <- tryAllM $ setSrcSpan expr_span $ -- Set the span so that qLocation can -- see where this splice is do { mb_result <- run_and_convert expr_span hval ; case mb_result of Left err -> failWithTc err Right result -> do { traceTc "Got HsSyn result:" (ppr_hs result) ; return $! result } } ; case either_tval of Right v -> return v Left se -> case fromException se of Just IOEnvFailure -> failM -- Error already in Tc monad _ -> fail_with_exn "run" se -- Exception }}} where -- see Note [Concealed TH exceptions] fail_with_exn :: Exception e => String -> e -> TcM a fail_with_exn phase exn = do exn_msg <- liftIO $ Panic.safeShowException exn let msg = vcat [text "Exception when trying to" <+> text phase <+> text "compile-time code:", nest 2 (text exn_msg), if show_code then text "Code:" <+> ppr expr else empty] failWithTc msg {- Note [Exceptions in TH] ~~~~~~~~~~~~~~~~~~~~~~~ Suppose we have something like this $( f 4 ) where f :: Int -> Q [Dec] f n | n>3 = fail "Too many declarations" | otherwise = ... The 'fail' is a user-generated failure, and should be displayed as a perfectly ordinary compiler error message, not a panic or anything like that. Here's how it's processed: * 'fail' is the monad fail. The monad instance for Q in TH.Syntax effectively transforms (fail s) to qReport True s >> fail where 'qReport' comes from the Quasi class and fail from its monad superclass. * The TcM monad is an instance of Quasi (see TcSplice), and it implements (qReport True s) by using addErr to add an error message to the bag of errors. The 'fail' in TcM raises an IOEnvFailure exception * 'qReport' forces the message to ensure any exception hidden in unevaluated thunk doesn't get into the bag of errors. Otherwise the following splice will triger panic (Trac #8987): $(fail undefined) See also Note [Concealed TH exceptions] * So, when running a splice, we catch all exceptions; then for - an IOEnvFailure exception, we assume the error is already in the error-bag (above) - other errors, we add an error to the bag and then fail Note [Concealed TH exceptions] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When displaying the error message contained in an exception originated from TH code, we need to make sure that the error message itself does not contain an exception. For example, when executing the following splice: $( error ("foo " ++ error "bar") ) the message for the outer exception is a thunk which will throw the inner exception when evaluated. For this reason, we display the message of a TH exception using the 'safeShowException' function, which recursively catches any exception thrown when showing an error message. To call runQ in the Tc monad, we need to make TcM an instance of Quasi: -} instance TH.Quasi TcM where qNewName s = do { u <- newUnique ; let i = getKey u ; return (TH.mkNameU s i) } -- 'msg' is forced to ensure exceptions don't escape, -- see Note [Exceptions in TH] qReport True msg = seqList msg $ addErr (text msg) qReport False msg = seqList msg $ addWarn NoReason (text msg) qLocation = do { m <- getModule ; l <- getSrcSpanM ; r <- case l of UnhelpfulSpan _ -> pprPanic "qLocation: Unhelpful location" (ppr l) RealSrcSpan s -> return s ; return (TH.Loc { TH.loc_filename = unpackFS (srcSpanFile r) , TH.loc_module = moduleNameString (moduleName m) , TH.loc_package = unitIdString (moduleUnitId m) , TH.loc_start = (srcSpanStartLine r, srcSpanStartCol r) , TH.loc_end = (srcSpanEndLine r, srcSpanEndCol r) }) } qLookupName = lookupName qReify = reify qReifyFixity nm = lookupThName nm >>= reifyFixity qReifyInstances = reifyInstances qReifyRoles = reifyRoles qReifyAnnotations = reifyAnnotations qReifyModule = reifyModule qReifyConStrictness nm = do { nm' <- lookupThName nm ; dc <- tcLookupDataCon nm' ; let bangs = dataConImplBangs dc ; return (map reifyDecidedStrictness bangs) } -- For qRecover, discard error messages if -- the recovery action is chosen. Otherwise -- we'll only fail higher up. qRecover recover main = tryTcDiscardingErrs recover main qAddDependentFile fp = do ref <- fmap tcg_dependent_files getGblEnv dep_files <- readTcRef ref writeTcRef ref (fp:dep_files) qAddTempFile suffix = do dflags <- getDynFlags liftIO $ newTempName dflags TFL_GhcSession suffix qAddTopDecls thds = do l <- getSrcSpanM let either_hval = convertToHsDecls l thds ds <- case either_hval of Left exn -> pprPanic "qAddTopDecls: can't convert top-level declarations" exn Right ds -> return ds mapM_ (checkTopDecl . unLoc) ds th_topdecls_var <- fmap tcg_th_topdecls getGblEnv updTcRef th_topdecls_var (\topds -> ds ++ topds) where checkTopDecl :: HsDecl GhcPs -> TcM () checkTopDecl (ValD _ binds) = mapM_ bindName (collectHsBindBinders binds) checkTopDecl (SigD _ _) = return () checkTopDecl (AnnD _ _) = return () checkTopDecl (ForD _ (ForeignImport { fd_name = L _ name })) = bindName name checkTopDecl _ = addErr $ text "Only function, value, annotation, and foreign import declarations may be added with addTopDecl" bindName :: RdrName -> TcM () bindName (Exact n) = do { th_topnames_var <- fmap tcg_th_topnames getGblEnv ; updTcRef th_topnames_var (\ns -> extendNameSet ns n) } bindName name = addErr $ hang (text "The binder" <+> quotes (ppr name) <+> ptext (sLit "is not a NameU.")) 2 (text "Probable cause: you used mkName instead of newName to generate a binding.") qAddForeignFilePath lang fp = do var <- fmap tcg_th_foreign_files getGblEnv updTcRef var ((lang, fp) :) qAddModFinalizer fin = do r <- liftIO $ mkRemoteRef fin fref <- liftIO $ mkForeignRef r (freeRemoteRef r) addModFinalizerRef fref qAddCorePlugin plugin = do hsc_env <- env_top <$> getEnv r <- liftIO $ findHomeModule hsc_env (mkModuleName plugin) let err = hang (text "addCorePlugin: invalid plugin module " <+> text (show plugin) ) 2 (text "Plugins in the current package can't be specified.") case r of Found {} -> addErr err FoundMultiple {} -> addErr err _ -> return () th_coreplugins_var <- tcg_th_coreplugins <$> getGblEnv updTcRef th_coreplugins_var (plugin:) qGetQ :: forall a. Typeable a => TcM (Maybe a) qGetQ = do th_state_var <- fmap tcg_th_state getGblEnv th_state <- readTcRef th_state_var -- See #10596 for why we use a scoped type variable here. return (Map.lookup (typeRep (Proxy :: Proxy a)) th_state >>= fromDynamic) qPutQ x = do th_state_var <- fmap tcg_th_state getGblEnv updTcRef th_state_var (\m -> Map.insert (typeOf x) (toDyn x) m) qIsExtEnabled = xoptM qExtsEnabled = EnumSet.toList . extensionFlags . hsc_dflags <$> getTopEnv -- | Adds a mod finalizer reference to the local environment. addModFinalizerRef :: ForeignRef (TH.Q ()) -> TcM () addModFinalizerRef finRef = do th_stage <- getStage case th_stage of RunSplice th_modfinalizers_var -> updTcRef th_modfinalizers_var (finRef :) -- This case happens only if a splice is executed and the caller does -- not set the 'ThStage' to 'RunSplice' to collect finalizers. -- See Note [Delaying modFinalizers in untyped splices] in RnSplice. _ -> pprPanic "addModFinalizer was called when no finalizers were collected" (ppr th_stage) -- | Releases the external interpreter state. finishTH :: TcM () finishTH = do dflags <- getDynFlags when (gopt Opt_ExternalInterpreter dflags) $ do tcg <- getGblEnv writeTcRef (tcg_th_remote_state tcg) Nothing runTHExp :: ForeignHValue -> TcM TH.Exp runTHExp = runTH THExp runTHPat :: ForeignHValue -> TcM TH.Pat runTHPat = runTH THPat runTHType :: ForeignHValue -> TcM TH.Type runTHType = runTH THType runTHDec :: ForeignHValue -> TcM [TH.Dec] runTHDec = runTH THDec runTH :: Binary a => THResultType -> ForeignHValue -> TcM a runTH ty fhv = do hsc_env <- env_top <$> getEnv dflags <- getDynFlags if not (gopt Opt_ExternalInterpreter dflags) then do -- Run it in the local TcM hv <- liftIO $ wormhole dflags fhv r <- runQuasi (unsafeCoerce# hv :: TH.Q a) return r else -- Run it on the server. For an overview of how TH works with -- Remote GHCi, see Note [Remote Template Haskell] in -- libraries/ghci/GHCi/TH.hs. withIServ hsc_env $ \i -> do rstate <- getTHState i loc <- TH.qLocation liftIO $ withForeignRef rstate $ \state_hv -> withForeignRef fhv $ \q_hv -> writeIServ i (putMessage (RunTH state_hv q_hv ty (Just loc))) runRemoteTH i [] bs <- readQResult i return $! runGet get (LB.fromStrict bs) -- | communicate with a remotely-running TH computation until it finishes. -- See Note [Remote Template Haskell] in libraries/ghci/GHCi/TH.hs. runRemoteTH :: IServ -> [Messages] -- saved from nested calls to qRecover -> TcM () runRemoteTH iserv recovers = do THMsg msg <- liftIO $ readIServ iserv getTHMessage case msg of RunTHDone -> return () StartRecover -> do -- Note [TH recover with -fexternal-interpreter] v <- getErrsVar msgs <- readTcRef v writeTcRef v emptyMessages runRemoteTH iserv (msgs : recovers) EndRecover caught_error -> do let (prev_msgs@(prev_warns,prev_errs), rest) = case recovers of [] -> panic "EndRecover" a : b -> (a,b) v <- getErrsVar (warn_msgs,_) <- readTcRef v -- keep the warnings only if there were no errors writeTcRef v $ if caught_error then prev_msgs else (prev_warns `unionBags` warn_msgs, prev_errs) runRemoteTH iserv rest _other -> do r <- handleTHMessage msg liftIO $ writeIServ iserv (put r) runRemoteTH iserv recovers -- | Read a value of type QResult from the iserv readQResult :: Binary a => IServ -> TcM a readQResult i = do qr <- liftIO $ readIServ i get case qr of QDone a -> return a QException str -> liftIO $ throwIO (ErrorCall str) QFail str -> fail str {- Note [TH recover with -fexternal-interpreter] Recover is slightly tricky to implement. The meaning of "recover a b" is - Do a - If it finished with no errors, then keep the warnings it generated - If it failed, discard any messages it generated, and do b Note that "failed" here can mean either (1) threw an exception (failTc) (2) generated an error message (addErrTcM) The messages are managed by GHC in the TcM monad, whereas the exception-handling is done in the ghc-iserv process, so we have to coordinate between the two. On the server: - emit a StartRecover message - run "a; FailIfErrs" inside a try - emit an (EndRecover x) message, where x = True if "a; FailIfErrs" failed - if "a; FailIfErrs" failed, run "b" Back in GHC, when we receive: FailIfErrrs failTc if there are any error messages (= failIfErrsM) StartRecover save the current messages and start with an empty set. EndRecover caught_error Restore the previous messages, and merge in the new messages if caught_error is false. -} -- | Retrieve (or create, if it hasn't been created already), the -- remote TH state. The TH state is a remote reference to an IORef -- QState living on the server, and we have to pass this to each RunTH -- call we make. -- -- The TH state is stored in tcg_th_remote_state in the TcGblEnv. -- getTHState :: IServ -> TcM (ForeignRef (IORef QState)) getTHState i = do tcg <- getGblEnv th_state <- readTcRef (tcg_th_remote_state tcg) case th_state of Just rhv -> return rhv Nothing -> do hsc_env <- env_top <$> getEnv fhv <- liftIO $ mkFinalizedHValue hsc_env =<< iservCall i StartTH writeTcRef (tcg_th_remote_state tcg) (Just fhv) return fhv wrapTHResult :: TcM a -> TcM (THResult a) wrapTHResult tcm = do e <- tryM tcm -- only catch 'fail', treat everything else as catastrophic case e of Left e -> return (THException (show e)) Right a -> return (THComplete a) handleTHMessage :: THMessage a -> TcM a handleTHMessage msg = case msg of NewName a -> wrapTHResult $ TH.qNewName a Report b str -> wrapTHResult $ TH.qReport b str LookupName b str -> wrapTHResult $ TH.qLookupName b str Reify n -> wrapTHResult $ TH.qReify n ReifyFixity n -> wrapTHResult $ TH.qReifyFixity n ReifyInstances n ts -> wrapTHResult $ TH.qReifyInstances n ts ReifyRoles n -> wrapTHResult $ TH.qReifyRoles n ReifyAnnotations lookup tyrep -> wrapTHResult $ (map B.pack <$> getAnnotationsByTypeRep lookup tyrep) ReifyModule m -> wrapTHResult $ TH.qReifyModule m ReifyConStrictness nm -> wrapTHResult $ TH.qReifyConStrictness nm AddDependentFile f -> wrapTHResult $ TH.qAddDependentFile f AddTempFile s -> wrapTHResult $ TH.qAddTempFile s AddModFinalizer r -> do hsc_env <- env_top <$> getEnv wrapTHResult $ liftIO (mkFinalizedHValue hsc_env r) >>= addModFinalizerRef AddCorePlugin str -> wrapTHResult $ TH.qAddCorePlugin str AddTopDecls decs -> wrapTHResult $ TH.qAddTopDecls decs AddForeignFilePath lang str -> wrapTHResult $ TH.qAddForeignFilePath lang str IsExtEnabled ext -> wrapTHResult $ TH.qIsExtEnabled ext ExtsEnabled -> wrapTHResult $ TH.qExtsEnabled FailIfErrs -> wrapTHResult failIfErrsM _ -> panic ("handleTHMessage: unexpected message " ++ show msg) getAnnotationsByTypeRep :: TH.AnnLookup -> TypeRep -> TcM [[Word8]] getAnnotationsByTypeRep th_name tyrep = do { name <- lookupThAnnLookup th_name ; topEnv <- getTopEnv ; epsHptAnns <- liftIO $ prepareAnnotations topEnv Nothing ; tcg <- getGblEnv ; let selectedEpsHptAnns = findAnnsByTypeRep epsHptAnns name tyrep ; let selectedTcgAnns = findAnnsByTypeRep (tcg_ann_env tcg) name tyrep ; return (selectedEpsHptAnns ++ selectedTcgAnns) } {- ************************************************************************ * * Instance Testing * * ************************************************************************ -} reifyInstances :: TH.Name -> [TH.Type] -> TcM [TH.Dec] reifyInstances th_nm th_tys = addErrCtxt (text "In the argument of reifyInstances:" <+> ppr_th th_nm <+> sep (map ppr_th th_tys)) $ do { loc <- getSrcSpanM ; rdr_ty <- cvt loc (mkThAppTs (TH.ConT th_nm) th_tys) -- #9262 says to bring vars into scope, like in HsForAllTy case -- of rnHsTyKi ; free_vars <- extractHsTyRdrTyVars rdr_ty ; let tv_rdrs = freeKiTyVarsAllVars free_vars -- Rename to HsType Name ; ((tv_names, rn_ty), _fvs) <- checkNoErrs $ -- If there are out-of-scope Names here, then we -- must error before proceeding to typecheck the -- renamed type, as that will result in GHC -- internal errors (#13837). bindLRdrNames tv_rdrs $ \ tv_names -> do { (rn_ty, fvs) <- rnLHsType doc rdr_ty ; return ((tv_names, rn_ty), fvs) } ; (_tvs, ty) <- solveEqualities $ tcImplicitTKBndrs ReifySkol tv_names $ fst <$> tcLHsType rn_ty ; ty <- zonkTcTypeToType emptyZonkEnv ty -- Substitute out the meta type variables -- In particular, the type might have kind -- variables inside it (Trac #7477) ; traceTc "reifyInstances" (ppr ty $$ ppr (typeKind ty)) ; case splitTyConApp_maybe ty of -- This expands any type synonyms Just (tc, tys) -- See Trac #7910 | Just cls <- tyConClass_maybe tc -> do { inst_envs <- tcGetInstEnvs ; let (matches, unifies, _) = lookupInstEnv False inst_envs cls tys ; traceTc "reifyInstances1" (ppr matches) ; reifyClassInstances cls (map fst matches ++ unifies) } | isOpenFamilyTyCon tc -> do { inst_envs <- tcGetFamInstEnvs ; let matches = lookupFamInstEnv inst_envs tc tys ; traceTc "reifyInstances2" (ppr matches) ; reifyFamilyInstances tc (map fim_instance matches) } _ -> bale_out (hang (text "reifyInstances:" <+> quotes (ppr ty)) 2 (text "is not a class constraint or type family application")) } where doc = ClassInstanceCtx bale_out msg = failWithTc msg cvt :: SrcSpan -> TH.Type -> TcM (LHsType GhcPs) cvt loc th_ty = case convertToHsType loc th_ty of Left msg -> failWithTc msg Right ty -> return ty {- ************************************************************************ * * Reification * * ************************************************************************ -} lookupName :: Bool -- True <=> type namespace -- False <=> value namespace -> String -> TcM (Maybe TH.Name) lookupName is_type_name s = do { lcl_env <- getLocalRdrEnv ; case lookupLocalRdrEnv lcl_env rdr_name of Just n -> return (Just (reifyName n)) Nothing -> do { mb_nm <- lookupGlobalOccRn_maybe rdr_name ; return (fmap reifyName mb_nm) } } where th_name = TH.mkName s -- Parses M.x into a base of 'x' and a module of 'M' occ_fs :: FastString occ_fs = mkFastString (TH.nameBase th_name) occ :: OccName occ | is_type_name = if isLexVarSym occ_fs || isLexCon occ_fs then mkTcOccFS occ_fs else mkTyVarOccFS occ_fs | otherwise = if isLexCon occ_fs then mkDataOccFS occ_fs else mkVarOccFS occ_fs rdr_name = case TH.nameModule th_name of Nothing -> mkRdrUnqual occ Just mod -> mkRdrQual (mkModuleName mod) occ getThing :: TH.Name -> TcM TcTyThing getThing th_name = do { name <- lookupThName th_name ; traceIf (text "reify" <+> text (show th_name) <+> brackets (ppr_ns th_name) <+> ppr name) ; tcLookupTh name } -- ToDo: this tcLookup could fail, which would give a -- rather unhelpful error message where ppr_ns (TH.Name _ (TH.NameG TH.DataName _pkg _mod)) = text "data" ppr_ns (TH.Name _ (TH.NameG TH.TcClsName _pkg _mod)) = text "tc" ppr_ns (TH.Name _ (TH.NameG TH.VarName _pkg _mod)) = text "var" ppr_ns _ = panic "reify/ppr_ns" reify :: TH.Name -> TcM TH.Info reify th_name = do { traceTc "reify 1" (text (TH.showName th_name)) ; thing <- getThing th_name ; traceTc "reify 2" (ppr thing) ; reifyThing thing } lookupThName :: TH.Name -> TcM Name lookupThName th_name = do mb_name <- lookupThName_maybe th_name case mb_name of Nothing -> failWithTc (notInScope th_name) Just name -> return name lookupThName_maybe :: TH.Name -> TcM (Maybe Name) lookupThName_maybe th_name = do { names <- mapMaybeM lookup (thRdrNameGuesses th_name) -- Pick the first that works -- E.g. reify (mkName "A") will pick the class A in preference to the data constructor A ; return (listToMaybe names) } where lookup rdr_name = do { -- Repeat much of lookupOccRn, because we want -- to report errors in a TH-relevant way ; rdr_env <- getLocalRdrEnv ; case lookupLocalRdrEnv rdr_env rdr_name of Just name -> return (Just name) Nothing -> lookupGlobalOccRn_maybe rdr_name } tcLookupTh :: Name -> TcM TcTyThing -- This is a specialised version of TcEnv.tcLookup; specialised mainly in that -- it gives a reify-related error message on failure, whereas in the normal -- tcLookup, failure is a bug. tcLookupTh name = do { (gbl_env, lcl_env) <- getEnvs ; case lookupNameEnv (tcl_env lcl_env) name of { Just thing -> return thing; Nothing -> case lookupNameEnv (tcg_type_env gbl_env) name of { Just thing -> return (AGlobal thing); Nothing -> -- EZY: I don't think this choice matters, no TH in signatures! if nameIsLocalOrFrom (tcg_semantic_mod gbl_env) name then -- It's defined in this module failWithTc (notInEnv name) else do { mb_thing <- tcLookupImported_maybe name ; case mb_thing of Succeeded thing -> return (AGlobal thing) Failed msg -> failWithTc msg }}}} notInScope :: TH.Name -> SDoc notInScope th_name = quotes (text (TH.pprint th_name)) <+> text "is not in scope at a reify" -- Ugh! Rather an indirect way to display the name notInEnv :: Name -> SDoc notInEnv name = quotes (ppr name) <+> text "is not in the type environment at a reify" ------------------------------ reifyRoles :: TH.Name -> TcM [TH.Role] reifyRoles th_name = do { thing <- getThing th_name ; case thing of AGlobal (ATyCon tc) -> return (map reify_role (tyConRoles tc)) _ -> failWithTc (text "No roles associated with" <+> (ppr thing)) } where reify_role Nominal = TH.NominalR reify_role Representational = TH.RepresentationalR reify_role Phantom = TH.PhantomR ------------------------------ reifyThing :: TcTyThing -> TcM TH.Info -- The only reason this is monadic is for error reporting, -- which in turn is mainly for the case when TH can't express -- some random GHC extension reifyThing (AGlobal (AnId id)) = do { ty <- reifyType (idType id) ; let v = reifyName id ; case idDetails id of ClassOpId cls -> return (TH.ClassOpI v ty (reifyName cls)) RecSelId{sel_tycon=RecSelData tc} -> return (TH.VarI (reifySelector id tc) ty Nothing) _ -> return (TH.VarI v ty Nothing) } reifyThing (AGlobal (ATyCon tc)) = reifyTyCon tc reifyThing (AGlobal (AConLike (RealDataCon dc))) = do { let name = dataConName dc ; ty <- reifyType (idType (dataConWrapId dc)) ; return (TH.DataConI (reifyName name) ty (reifyName (dataConOrigTyCon dc))) } reifyThing (AGlobal (AConLike (PatSynCon ps))) = do { let name = reifyName ps ; ty <- reifyPatSynType (patSynSig ps) ; return (TH.PatSynI name ty) } reifyThing (ATcId {tct_id = id}) = do { ty1 <- zonkTcType (idType id) -- Make use of all the info we have, even -- though it may be incomplete ; ty2 <- reifyType ty1 ; return (TH.VarI (reifyName id) ty2 Nothing) } reifyThing (ATyVar tv tv1) = do { ty1 <- zonkTcTyVar tv1 ; ty2 <- reifyType ty1 ; return (TH.TyVarI (reifyName tv) ty2) } reifyThing thing = pprPanic "reifyThing" (pprTcTyThingCategory thing) ------------------------------------------- reifyAxBranch :: TyCon -> CoAxBranch -> TcM TH.TySynEqn reifyAxBranch fam_tc (CoAxBranch { cab_lhs = lhs, cab_rhs = rhs }) -- remove kind patterns (#8884) = do { let lhs_types_only = filterOutInvisibleTypes fam_tc lhs ; lhs' <- reifyTypes lhs_types_only ; annot_th_lhs <- zipWith3M annotThType (mkIsPolyTvs fam_tvs) lhs_types_only lhs' ; rhs' <- reifyType rhs ; return (TH.TySynEqn annot_th_lhs rhs') } where fam_tvs = tyConVisibleTyVars fam_tc reifyTyCon :: TyCon -> TcM TH.Info reifyTyCon tc | Just cls <- tyConClass_maybe tc = reifyClass cls | isFunTyCon tc = return (TH.PrimTyConI (reifyName tc) 2 False) | isPrimTyCon tc = return (TH.PrimTyConI (reifyName tc) (tyConArity tc) (isUnliftedTyCon tc)) | isTypeFamilyTyCon tc = do { let tvs = tyConTyVars tc res_kind = tyConResKind tc resVar = famTcResVar tc ; kind' <- reifyKind res_kind ; let (resultSig, injectivity) = case resVar of Nothing -> (TH.KindSig kind', Nothing) Just name -> let thName = reifyName name injAnnot = tyConInjectivityInfo tc sig = TH.TyVarSig (TH.KindedTV thName kind') inj = case injAnnot of NotInjective -> Nothing Injective ms -> Just (TH.InjectivityAnn thName injRHS) where injRHS = map (reifyName . tyVarName) (filterByList ms tvs) in (sig, inj) ; tvs' <- reifyTyVars (tyConVisibleTyVars tc) ; let tfHead = TH.TypeFamilyHead (reifyName tc) tvs' resultSig injectivity ; if isOpenTypeFamilyTyCon tc then do { fam_envs <- tcGetFamInstEnvs ; instances <- reifyFamilyInstances tc (familyInstances fam_envs tc) ; return (TH.FamilyI (TH.OpenTypeFamilyD tfHead) instances) } else do { eqns <- case isClosedSynFamilyTyConWithAxiom_maybe tc of Just ax -> mapM (reifyAxBranch tc) $ fromBranches $ coAxiomBranches ax Nothing -> return [] ; return (TH.FamilyI (TH.ClosedTypeFamilyD tfHead eqns) []) } } | isDataFamilyTyCon tc = do { let res_kind = tyConResKind tc ; kind' <- fmap Just (reifyKind res_kind) ; tvs' <- reifyTyVars (tyConVisibleTyVars tc) ; fam_envs <- tcGetFamInstEnvs ; instances <- reifyFamilyInstances tc (familyInstances fam_envs tc) ; return (TH.FamilyI (TH.DataFamilyD (reifyName tc) tvs' kind') instances) } | Just (_, rhs) <- synTyConDefn_maybe tc -- Vanilla type synonym = do { rhs' <- reifyType rhs ; tvs' <- reifyTyVars (tyConVisibleTyVars tc) ; return (TH.TyConI (TH.TySynD (reifyName tc) tvs' rhs')) } | otherwise = do { cxt <- reifyCxt (tyConStupidTheta tc) ; let tvs = tyConTyVars tc dataCons = tyConDataCons tc isGadt = isGadtSyntaxTyCon tc ; cons <- mapM (reifyDataCon isGadt (mkTyVarTys tvs)) dataCons ; r_tvs <- reifyTyVars (tyConVisibleTyVars tc) ; let name = reifyName tc deriv = [] -- Don't know about deriving decl | isNewTyCon tc = TH.NewtypeD cxt name r_tvs Nothing (head cons) deriv | otherwise = TH.DataD cxt name r_tvs Nothing cons deriv ; return (TH.TyConI decl) } reifyDataCon :: Bool -> [Type] -> DataCon -> TcM TH.Con reifyDataCon isGadtDataCon tys dc = do { let -- used for H98 data constructors (ex_tvs, theta, arg_tys) = dataConInstSig dc tys -- used for GADTs data constructors g_user_tvs' = dataConUserTyVars dc (g_univ_tvs, _, g_eq_spec, g_theta', g_arg_tys', g_res_ty') = dataConFullSig dc (srcUnpks, srcStricts) = mapAndUnzip reifySourceBang (dataConSrcBangs dc) dcdBangs = zipWith TH.Bang srcUnpks srcStricts fields = dataConFieldLabels dc name = reifyName dc -- Universal tvs present in eq_spec need to be filtered out, as -- they will not appear anywhere in the type. eq_spec_tvs = mkVarSet (map eqSpecTyVar g_eq_spec) ; (univ_subst, _) -- See Note [Freshen reified GADT constructors' universal tyvars] <- freshenTyVarBndrs $ filterOut (`elemVarSet` eq_spec_tvs) g_univ_tvs ; let (tvb_subst, g_user_tvs) = substTyVarBndrs univ_subst g_user_tvs' g_theta = substTys tvb_subst g_theta' g_arg_tys = substTys tvb_subst g_arg_tys' g_res_ty = substTy tvb_subst g_res_ty' ; r_arg_tys <- reifyTypes (if isGadtDataCon then g_arg_tys else arg_tys) ; main_con <- if | not (null fields) && not isGadtDataCon -> return $ TH.RecC name (zip3 (map reifyFieldLabel fields) dcdBangs r_arg_tys) | not (null fields) -> do { res_ty <- reifyType g_res_ty ; return $ TH.RecGadtC [name] (zip3 (map (reifyName . flSelector) fields) dcdBangs r_arg_tys) res_ty } -- We need to check not isGadtDataCon here because GADT -- constructors can be declared infix. -- See Note [Infix GADT constructors] in TcTyClsDecls. | dataConIsInfix dc && not isGadtDataCon -> ASSERT( arg_tys `lengthIs` 2 ) do { let [r_a1, r_a2] = r_arg_tys [s1, s2] = dcdBangs ; return $ TH.InfixC (s1,r_a1) name (s2,r_a2) } | isGadtDataCon -> do { res_ty <- reifyType g_res_ty ; return $ TH.GadtC [name] (dcdBangs `zip` r_arg_tys) res_ty } | otherwise -> return $ TH.NormalC name (dcdBangs `zip` r_arg_tys) ; let (ex_tvs', theta') | isGadtDataCon = (g_user_tvs, g_theta) | otherwise = (ex_tvs, theta) ret_con | null ex_tvs' && null theta' = return main_con | otherwise = do { cxt <- reifyCxt theta' ; ex_tvs'' <- reifyTyVars ex_tvs' ; return (TH.ForallC ex_tvs'' cxt main_con) } ; ASSERT( arg_tys `equalLength` dcdBangs ) ret_con } {- Note [Freshen reified GADT constructors' universal tyvars] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Suppose one were to reify this GADT: data a :~: b where Refl :: forall a b. (a ~ b) => a :~: b We ought to be careful here about the uniques we give to the occurrences of `a` and `b` in this definition. That is because in the original DataCon, all uses of `a` and `b` have the same unique, since `a` and `b` are both universally quantified type variables--that is, they are used in both the (:~:) tycon as well as in the constructor type signature. But when we turn the DataCon definition into the reified one, the `a` and `b` in the constructor type signature becomes differently scoped than the `a` and `b` in `data a :~: b`. While it wouldn't technically be *wrong* per se to re-use the same uniques for `a` and `b` across these two different scopes, it's somewhat annoying for end users of Template Haskell, since they wouldn't be able to rely on the assumption that all TH names have globally distinct uniques (#13885). For this reason, we freshen the universally quantified tyvars that go into the reified GADT constructor type signature to give them distinct uniques from their counterparts in the tycon. -} ------------------------------ reifyClass :: Class -> TcM TH.Info reifyClass cls = do { cxt <- reifyCxt theta ; inst_envs <- tcGetInstEnvs ; insts <- reifyClassInstances cls (InstEnv.classInstances inst_envs cls) ; assocTys <- concatMapM reifyAT ats ; ops <- concatMapM reify_op op_stuff ; tvs' <- reifyTyVars (tyConVisibleTyVars (classTyCon cls)) ; let dec = TH.ClassD cxt (reifyName cls) tvs' fds' (assocTys ++ ops) ; return (TH.ClassI dec insts) } where (_, fds, theta, _, ats, op_stuff) = classExtraBigSig cls fds' = map reifyFunDep fds reify_op (op, def_meth) = do { ty <- reifyType (idType op) ; let nm' = reifyName op ; case def_meth of Just (_, GenericDM gdm_ty) -> do { gdm_ty' <- reifyType gdm_ty ; return [TH.SigD nm' ty, TH.DefaultSigD nm' gdm_ty'] } _ -> return [TH.SigD nm' ty] } reifyAT :: ClassATItem -> TcM [TH.Dec] reifyAT (ATI tycon def) = do tycon' <- reifyTyCon tycon case tycon' of TH.FamilyI dec _ -> do let (tyName, tyArgs) = tfNames dec (dec :) <$> maybe (return []) (fmap (:[]) . reifyDefImpl tyName tyArgs . fst) def _ -> pprPanic "reifyAT" (text (show tycon')) reifyDefImpl :: TH.Name -> [TH.Name] -> Type -> TcM TH.Dec reifyDefImpl n args ty = TH.TySynInstD n . TH.TySynEqn (map TH.VarT args) <$> reifyType ty tfNames :: TH.Dec -> (TH.Name, [TH.Name]) tfNames (TH.OpenTypeFamilyD (TH.TypeFamilyHead n args _ _)) = (n, map bndrName args) tfNames d = pprPanic "tfNames" (text (show d)) bndrName :: TH.TyVarBndr -> TH.Name bndrName (TH.PlainTV n) = n bndrName (TH.KindedTV n _) = n ------------------------------ -- | Annotate (with TH.SigT) a type if the first parameter is True -- and if the type contains a free variable. -- This is used to annotate type patterns for poly-kinded tyvars in -- reifying class and type instances. See #8953 and th/T8953. annotThType :: Bool -- True <=> annotate -> TyCoRep.Type -> TH.Type -> TcM TH.Type -- tiny optimization: if the type is annotated, don't annotate again. annotThType _ _ th_ty@(TH.SigT {}) = return th_ty annotThType True ty th_ty | not $ isEmptyVarSet $ filterVarSet isTyVar $ tyCoVarsOfType ty = do { let ki = typeKind ty ; th_ki <- reifyKind ki ; return (TH.SigT th_ty th_ki) } annotThType _ _ th_ty = return th_ty -- | For every type variable in the input, -- report whether or not the tv is poly-kinded. This is used to eventually -- feed into 'annotThType'. mkIsPolyTvs :: [TyVar] -> [Bool] mkIsPolyTvs = map is_poly_tv where is_poly_tv tv = not $ isEmptyVarSet $ filterVarSet isTyVar $ tyCoVarsOfType $ tyVarKind tv ------------------------------ reifyClassInstances :: Class -> [ClsInst] -> TcM [TH.Dec] reifyClassInstances cls insts = mapM (reifyClassInstance (mkIsPolyTvs tvs)) insts where tvs = tyConVisibleTyVars (classTyCon cls) reifyClassInstance :: [Bool] -- True <=> the corresponding tv is poly-kinded -- includes only *visible* tvs -> ClsInst -> TcM TH.Dec reifyClassInstance is_poly_tvs i = do { cxt <- reifyCxt theta ; let vis_types = filterOutInvisibleTypes cls_tc types ; thtypes <- reifyTypes vis_types ; annot_thtypes <- zipWith3M annotThType is_poly_tvs vis_types thtypes ; let head_ty = mkThAppTs (TH.ConT (reifyName cls)) annot_thtypes ; return $ (TH.InstanceD over cxt head_ty []) } where (_tvs, theta, cls, types) = tcSplitDFunTy (idType dfun) cls_tc = classTyCon cls dfun = instanceDFunId i over = case overlapMode (is_flag i) of NoOverlap _ -> Nothing Overlappable _ -> Just TH.Overlappable Overlapping _ -> Just TH.Overlapping Overlaps _ -> Just TH.Overlaps Incoherent _ -> Just TH.Incoherent ------------------------------ reifyFamilyInstances :: TyCon -> [FamInst] -> TcM [TH.Dec] reifyFamilyInstances fam_tc fam_insts = mapM (reifyFamilyInstance (mkIsPolyTvs fam_tvs)) fam_insts where fam_tvs = tyConVisibleTyVars fam_tc reifyFamilyInstance :: [Bool] -- True <=> the corresponding tv is poly-kinded -- includes only *visible* tvs -> FamInst -> TcM TH.Dec reifyFamilyInstance is_poly_tvs inst@(FamInst { fi_flavor = flavor , fi_fam = fam , fi_tvs = fam_tvs , fi_tys = lhs , fi_rhs = rhs }) = case flavor of SynFamilyInst -> -- remove kind patterns (#8884) do { let lhs_types_only = filterOutInvisibleTypes fam_tc lhs ; th_lhs <- reifyTypes lhs_types_only ; annot_th_lhs <- zipWith3M annotThType is_poly_tvs lhs_types_only th_lhs ; th_rhs <- reifyType rhs ; return (TH.TySynInstD (reifyName fam) (TH.TySynEqn annot_th_lhs th_rhs)) } DataFamilyInst rep_tc -> do { let rep_tvs = tyConTyVars rep_tc fam' = reifyName fam -- eta-expand lhs types, because sometimes data/newtype -- instances are eta-reduced; See Trac #9692 -- See Note [Eta reduction for data family axioms] -- in TcInstDcls (_rep_tc, rep_tc_args) = splitTyConApp rhs etad_tyvars = dropList rep_tc_args rep_tvs etad_tys = mkTyVarTys etad_tyvars eta_expanded_tvs = mkTyVarTys fam_tvs `chkAppend` etad_tys eta_expanded_lhs = lhs `chkAppend` etad_tys dataCons = tyConDataCons rep_tc isGadt = isGadtSyntaxTyCon rep_tc ; cons <- mapM (reifyDataCon isGadt eta_expanded_tvs) dataCons ; let types_only = filterOutInvisibleTypes fam_tc eta_expanded_lhs ; th_tys <- reifyTypes types_only ; annot_th_tys <- zipWith3M annotThType is_poly_tvs types_only th_tys ; return $ if isNewTyCon rep_tc then TH.NewtypeInstD [] fam' annot_th_tys Nothing (head cons) [] else TH.DataInstD [] fam' annot_th_tys Nothing cons [] } where fam_tc = famInstTyCon inst ------------------------------ reifyType :: TyCoRep.Type -> TcM TH.Type -- Monadic only because of failure reifyType ty | tcIsLiftedTypeKind ty = return TH.StarT -- Make sure to use tcIsLiftedTypeKind here, since we don't want to confuse it -- with Constraint (#14869). reifyType ty@(ForAllTy {}) = reify_for_all ty reifyType (LitTy t) = do { r <- reifyTyLit t; return (TH.LitT r) } reifyType (TyVarTy tv) = return (TH.VarT (reifyName tv)) reifyType (TyConApp tc tys) = reify_tc_app tc tys -- Do not expand type synonyms here reifyType (AppTy t1 t2) = do { [r1,r2] <- reifyTypes [t1,t2] ; return (r1 `TH.AppT` r2) } reifyType ty@(FunTy t1 t2) | isPredTy t1 = reify_for_all ty -- Types like ((?x::Int) => Char -> Char) | otherwise = do { [r1,r2] <- reifyTypes [t1,t2] ; return (TH.ArrowT `TH.AppT` r1 `TH.AppT` r2) } reifyType (CastTy t _) = reifyType t -- Casts are ignored in TH reifyType ty@(CoercionTy {})= noTH (sLit "coercions in types") (ppr ty) reify_for_all :: TyCoRep.Type -> TcM TH.Type reify_for_all ty = do { cxt' <- reifyCxt cxt; ; tau' <- reifyType tau ; tvs' <- reifyTyVars tvs ; return (TH.ForallT tvs' cxt' tau') } where (tvs, cxt, tau) = tcSplitSigmaTy ty reifyTyLit :: TyCoRep.TyLit -> TcM TH.TyLit reifyTyLit (NumTyLit n) = return (TH.NumTyLit n) reifyTyLit (StrTyLit s) = return (TH.StrTyLit (unpackFS s)) reifyTypes :: [Type] -> TcM [TH.Type] reifyTypes = mapM reifyType reifyPatSynType :: ([TyVar], ThetaType, [TyVar], ThetaType, [Type], Type) -> TcM TH.Type -- reifies a pattern synonym's type and returns its *complete* type -- signature; see NOTE [Pattern synonym signatures and Template -- Haskell] reifyPatSynType (univTyVars, req, exTyVars, prov, argTys, resTy) = do { univTyVars' <- reifyTyVars univTyVars ; req' <- reifyCxt req ; exTyVars' <- reifyTyVars exTyVars ; prov' <- reifyCxt prov ; tau' <- reifyType (mkFunTys argTys resTy) ; return $ TH.ForallT univTyVars' req' $ TH.ForallT exTyVars' prov' tau' } reifyKind :: Kind -> TcM TH.Kind reifyKind = reifyType reifyCxt :: [PredType] -> TcM [TH.Pred] reifyCxt = mapM reifyPred reifyFunDep :: ([TyVar], [TyVar]) -> TH.FunDep reifyFunDep (xs, ys) = TH.FunDep (map reifyName xs) (map reifyName ys) reifyTyVars :: [TyVar] -> TcM [TH.TyVarBndr] reifyTyVars tvs = mapM reify_tv tvs where -- even if the kind is *, we need to include a kind annotation, -- in case a poly-kind would be inferred without the annotation. -- See #8953 or test th/T8953 reify_tv tv = TH.KindedTV name <$> reifyKind kind where kind = tyVarKind tv name = reifyName tv {- Note [Kind annotations on TyConApps] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A poly-kinded tycon sometimes needs a kind annotation to be unambiguous. For example: type family F a :: k type instance F Int = (Proxy :: * -> *) type instance F Bool = (Proxy :: (* -> *) -> *) It's hard to figure out where these annotations should appear, so we do this: Suppose we have a tycon application (T ty1 ... tyn). Assuming that T is not oversatured (more on this later), we can assume T's declaration is of the form T (tvb1 :: s1) ... (tvbn :: sn) :: p. If any kind variable that is free in p is not free in an injective position in tvb1 ... tvbn, then we put on a kind annotation, since we would not otherwise be able to infer the kind of the whole tycon application. The injective positions in a tyvar binder are the injective positions in the kind of its tyvar, provided the tyvar binder is either: * Anonymous. For example, in the promoted data constructor '(:): '(:) :: forall a. a -> [a] -> [a] The second and third tyvar binders (of kinds `a` and `[a]`) are both anonymous, so if we had '(:) 'True '[], then the inferred kinds of 'True and '[] would contribute to the inferred kind of '(:) 'True '[]. * Has required visibility. For example, in the type family: type family Wurble k (a :: k) :: k Wurble :: forall k -> k -> k The first tyvar binder (of kind `forall k`) has required visibility, so if we had Wurble (Maybe a) Nothing, then the inferred kind of Maybe a would contribute to the inferred kind of Wurble (Maybe a) Nothing. An injective position in a type is one that does not occur as an argument to a non-injective type constructor (e.g., non-injective type families). See injectiveVarsOfType. How can be sure that this is correct? That is, how can we be sure that in the event that we leave off a kind annotation, that one could infer the kind of the tycon application from its arguments? It's essentially a proof by induction: if we can infer the kinds of every subtree of a type, then the whole tycon application will have an inferrable kind--unless, of course, the remainder of the tycon application's kind has uninstantiated kind variables. An earlier implementation of this algorithm only checked if p contained any free variables. But this was unsatisfactory, since a datatype like this: data Foo = Foo (Proxy '[False, True]) Would be reified like this: data Foo = Foo (Proxy ('(:) False ('(:) True ('[] :: [Bool]) :: [Bool]) :: [Bool])) Which has a rather excessive amount of kind annotations. With the current algorithm, we instead reify Foo to this: data Foo = Foo (Proxy ('(:) False ('(:) True ('[] :: [Bool])))) Since in the case of '[], the kind p is [a], and there are no arguments in the kind of '[]. On the other hand, in the case of '(:) True '[], the kind p is (forall a. [a]), but a occurs free in the first and second arguments of the full kind of '(:), which is (forall a. a -> [a] -> [a]). (See Trac #14060.) What happens if T is oversaturated? That is, if T's kind has fewer than n arguments, in the case that the concrete application instantiates a result kind variable with an arrow kind? If we run out of arguments, we do not attach a kind annotation. This should be a rare case, indeed. Here is an example: data T1 :: k1 -> k2 -> * data T2 :: k1 -> k2 -> * type family G (a :: k) :: k type instance G T1 = T2 type instance F Char = (G T1 Bool :: (* -> *) -> *) -- F from above Here G's kind is (forall k. k -> k), and the desugared RHS of that last instance of F is (G (* -> (* -> *) -> *) (T1 * (* -> *)) Bool). According to the algorithm above, there are 3 arguments to G so we should peel off 3 arguments in G's kind. But G's kind has only two arguments. This is the rare special case, and we choose not to annotate the application of G with a kind signature. After all, we needn't do this, since that instance would be reified as: type instance F Char = G (T1 :: * -> (* -> *) -> *) Bool So the kind of G isn't ambiguous anymore due to the explicit kind annotation on its argument. See #8953 and test th/T8953. -} reify_tc_app :: TyCon -> [Type.Type] -> TcM TH.Type reify_tc_app tc tys = do { tys' <- reifyTypes (filterOutInvisibleTypes tc tys) ; maybe_sig_t (mkThAppTs r_tc tys') } where arity = tyConArity tc tc_binders = tyConBinders tc tc_res_kind = tyConResKind tc r_tc | isUnboxedSumTyCon tc = TH.UnboxedSumT (arity `div` 2) | isUnboxedTupleTyCon tc = TH.UnboxedTupleT (arity `div` 2) | isPromotedTupleTyCon tc = TH.PromotedTupleT (arity `div` 2) -- See Note [Unboxed tuple RuntimeRep vars] in TyCon | isTupleTyCon tc = if isPromotedDataCon tc then TH.PromotedTupleT arity else TH.TupleT arity | tc `hasKey` constraintKindTyConKey = TH.ConstraintT | tc `hasKey` funTyConKey = TH.ArrowT | tc `hasKey` listTyConKey = TH.ListT | tc `hasKey` nilDataConKey = TH.PromotedNilT | tc `hasKey` consDataConKey = TH.PromotedConsT | tc `hasKey` heqTyConKey = TH.EqualityT | tc `hasKey` eqPrimTyConKey = TH.EqualityT | tc `hasKey` eqReprPrimTyConKey = TH.ConT (reifyName coercibleTyCon) | isPromotedDataCon tc = TH.PromotedT (reifyName tc) | otherwise = TH.ConT (reifyName tc) -- See Note [Kind annotations on TyConApps] maybe_sig_t th_type | needs_kind_sig = do { let full_kind = typeKind (mkTyConApp tc tys) ; th_full_kind <- reifyKind full_kind ; return (TH.SigT th_type th_full_kind) } | otherwise = return th_type needs_kind_sig | GT <- compareLength tys tc_binders = False | otherwise = let (dropped_binders, remaining_binders) = splitAtList tys tc_binders result_kind = mkTyConKind remaining_binders tc_res_kind result_vars = tyCoVarsOfType result_kind dropped_vars = fvVarSet $ mapUnionFV injectiveVarsOfBinder dropped_binders in not (subVarSet result_vars dropped_vars) reifyPred :: TyCoRep.PredType -> TcM TH.Pred reifyPred ty -- We could reify the invisible parameter as a class but it seems -- nicer to support them properly... | isIPPred ty = noTH (sLit "implicit parameters") (ppr ty) | otherwise = reifyType ty ------------------------------ reifyName :: NamedThing n => n -> TH.Name reifyName thing | isExternalName name = mk_varg pkg_str mod_str occ_str | otherwise = TH.mkNameU occ_str (getKey (getUnique name)) -- Many of the things we reify have local bindings, and -- NameL's aren't supposed to appear in binding positions, so -- we use NameU. When/if we start to reify nested things, that -- have free variables, we may need to generate NameL's for them. where name = getName thing mod = ASSERT( isExternalName name ) nameModule name pkg_str = unitIdString (moduleUnitId mod) mod_str = moduleNameString (moduleName mod) occ_str = occNameString occ occ = nameOccName name mk_varg | OccName.isDataOcc occ = TH.mkNameG_d | OccName.isVarOcc occ = TH.mkNameG_v | OccName.isTcOcc occ = TH.mkNameG_tc | otherwise = pprPanic "reifyName" (ppr name) -- See Note [Reifying field labels] reifyFieldLabel :: FieldLabel -> TH.Name reifyFieldLabel fl | flIsOverloaded fl = TH.Name (TH.mkOccName occ_str) (TH.NameQ (TH.mkModName mod_str)) | otherwise = TH.mkNameG_v pkg_str mod_str occ_str where name = flSelector fl mod = ASSERT( isExternalName name ) nameModule name pkg_str = unitIdString (moduleUnitId mod) mod_str = moduleNameString (moduleName mod) occ_str = unpackFS (flLabel fl) reifySelector :: Id -> TyCon -> TH.Name reifySelector id tc = case find ((idName id ==) . flSelector) (tyConFieldLabels tc) of Just fl -> reifyFieldLabel fl Nothing -> pprPanic "reifySelector: missing field" (ppr id $$ ppr tc) ------------------------------ reifyFixity :: Name -> TcM (Maybe TH.Fixity) reifyFixity name = do { (found, fix) <- lookupFixityRn_help name ; return (if found then Just (conv_fix fix) else Nothing) } where conv_fix (BasicTypes.Fixity _ i d) = TH.Fixity i (conv_dir d) conv_dir BasicTypes.InfixR = TH.InfixR conv_dir BasicTypes.InfixL = TH.InfixL conv_dir BasicTypes.InfixN = TH.InfixN reifyUnpackedness :: DataCon.SrcUnpackedness -> TH.SourceUnpackedness reifyUnpackedness NoSrcUnpack = TH.NoSourceUnpackedness reifyUnpackedness SrcNoUnpack = TH.SourceNoUnpack reifyUnpackedness SrcUnpack = TH.SourceUnpack reifyStrictness :: DataCon.SrcStrictness -> TH.SourceStrictness reifyStrictness NoSrcStrict = TH.NoSourceStrictness reifyStrictness SrcStrict = TH.SourceStrict reifyStrictness SrcLazy = TH.SourceLazy reifySourceBang :: DataCon.HsSrcBang -> (TH.SourceUnpackedness, TH.SourceStrictness) reifySourceBang (HsSrcBang _ u s) = (reifyUnpackedness u, reifyStrictness s) reifyDecidedStrictness :: DataCon.HsImplBang -> TH.DecidedStrictness reifyDecidedStrictness HsLazy = TH.DecidedLazy reifyDecidedStrictness HsStrict = TH.DecidedStrict reifyDecidedStrictness HsUnpack{} = TH.DecidedUnpack ------------------------------ lookupThAnnLookup :: TH.AnnLookup -> TcM CoreAnnTarget lookupThAnnLookup (TH.AnnLookupName th_nm) = fmap NamedTarget (lookupThName th_nm) lookupThAnnLookup (TH.AnnLookupModule (TH.Module pn mn)) = return $ ModuleTarget $ mkModule (stringToUnitId $ TH.pkgString pn) (mkModuleName $ TH.modString mn) reifyAnnotations :: Data a => TH.AnnLookup -> TcM [a] reifyAnnotations th_name = do { name <- lookupThAnnLookup th_name ; topEnv <- getTopEnv ; epsHptAnns <- liftIO $ prepareAnnotations topEnv Nothing ; tcg <- getGblEnv ; let selectedEpsHptAnns = findAnns deserializeWithData epsHptAnns name ; let selectedTcgAnns = findAnns deserializeWithData (tcg_ann_env tcg) name ; return (selectedEpsHptAnns ++ selectedTcgAnns) } ------------------------------ modToTHMod :: Module -> TH.Module modToTHMod m = TH.Module (TH.PkgName $ unitIdString $ moduleUnitId m) (TH.ModName $ moduleNameString $ moduleName m) reifyModule :: TH.Module -> TcM TH.ModuleInfo reifyModule (TH.Module (TH.PkgName pkgString) (TH.ModName mString)) = do this_mod <- getModule let reifMod = mkModule (stringToUnitId pkgString) (mkModuleName mString) if (reifMod == this_mod) then reifyThisModule else reifyFromIface reifMod where reifyThisModule = do usages <- fmap (map modToTHMod . moduleEnvKeys . imp_mods) getImports return $ TH.ModuleInfo usages reifyFromIface reifMod = do iface <- loadInterfaceForModule (text "reifying module from TH for" <+> ppr reifMod) reifMod let usages = [modToTHMod m | usage <- mi_usages iface, Just m <- [usageToModule (moduleUnitId reifMod) usage] ] return $ TH.ModuleInfo usages usageToModule :: UnitId -> Usage -> Maybe Module usageToModule _ (UsageFile {}) = Nothing usageToModule this_pkg (UsageHomeModule { usg_mod_name = mn }) = Just $ mkModule this_pkg mn usageToModule _ (UsagePackageModule { usg_mod = m }) = Just m usageToModule _ (UsageMergedRequirement { usg_mod = m }) = Just m ------------------------------ mkThAppTs :: TH.Type -> [TH.Type] -> TH.Type mkThAppTs fun_ty arg_tys = foldl TH.AppT fun_ty arg_tys noTH :: LitString -> SDoc -> TcM a noTH s d = failWithTc (hsep [text "Can't represent" <+> ptext s <+> text "in Template Haskell:", nest 2 d]) ppr_th :: TH.Ppr a => a -> SDoc ppr_th x = text (TH.pprint x) {- Note [Reifying field labels] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When reifying a datatype declared with DuplicateRecordFields enabled, we want the reified names of the fields to be labels rather than selector functions. That is, we want (reify ''T) and (reify 'foo) to produce data T = MkT { foo :: Int } foo :: T -> Int rather than data T = MkT { $sel:foo:MkT :: Int } $sel:foo:MkT :: T -> Int because otherwise TH code that uses the field names as strings will silently do the wrong thing. Thus we use the field label (e.g. foo) as the OccName, rather than the selector (e.g. $sel:foo:MkT). Since the Orig name M.foo isn't in the environment, NameG can't be used to represent such fields. Instead, reifyFieldLabel uses NameQ. However, this means that extracting the field name from the output of reify, and trying to reify it again, may fail with an ambiguity error if there are multiple such fields defined in the module (see the test case overloadedrecflds/should_fail/T11103.hs). The "proper" fix requires changes to the TH AST to make it able to represent duplicate record fields. -}