\section[TcBinds]{TcBinds}
\begin{code}
-module TcBinds ( tcBindsAndThen, tcTopBinds,
- tcHsBootSigs, tcMonoBinds, tcSpecSigs,
+module TcBinds ( tcLocalBinds, tcTopBinds,
+ tcHsBootSigs, tcMonoBinds,
+ TcPragFun, tcSpecPrag, tcPrags, mkPragFun,
badBootDeclErr ) where
#include "HsVersions.h"
import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun )
-import {-# SOURCE #-} TcExpr ( tcCheckSigma, tcCheckRho )
+import {-# SOURCE #-} TcExpr ( tcCheckRho )
import DynFlags ( DynFlag(Opt_MonomorphismRestriction) )
-import HsSyn ( HsExpr(..), HsBind(..), LHsBinds, Sig(..),
- LSig, Match(..), HsBindGroup(..), IPBind(..),
- HsType(..), HsExplicitForAll(..), hsLTyVarNames, isVanillaLSig,
- LPat, GRHSs, MatchGroup(..), emptyLHsBinds, isEmptyLHsBinds,
+import HsSyn ( HsExpr(..), HsBind(..), LHsBinds, LHsBind, Sig(..),
+ HsLocalBinds(..), HsValBinds(..), HsIPBinds(..),
+ LSig, Match(..), IPBind(..), Prag(..),
+ HsType(..), LHsType, HsExplicitForAll(..), hsLTyVarNames,
+ isVanillaLSig, sigName, placeHolderNames, isPragLSig,
+ LPat, GRHSs, MatchGroup(..), isEmptyLHsBinds,
collectHsBindBinders, collectPatBinders, pprPatBind
)
-import TcHsSyn ( zonkId, mkHsLet )
+import TcHsSyn ( zonkId, (<$>) )
import TcRnMonad
import Inst ( newDictsAtLoc, newIPDict, instToId )
import TcEnv ( tcExtendIdEnv, tcExtendIdEnv2, tcExtendTyVarEnv2,
newLocalName, tcLookupLocalIds, pprBinders,
tcGetGlobalTyVars )
-import TcUnify ( Expected(..), tcInfer, unifyTheta,
+import TcUnify ( Expected(..), tcInfer, unifyTheta, tcSub,
bleatEscapedTvs, sigCtxt )
-import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted,
- tcSimplifyToDicts, tcSimplifyIPs )
+import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck,
+ tcSimplifyRestricted, tcSimplifyIPs )
import TcHsType ( tcHsSigType, UserTypeCtxt(..), tcAddLetBoundTyVars,
TcSigInfo(..), TcSigFun, lookupSig
)
import TcSimplify ( bindInstsOfLocalFuns )
import TcMType ( newTyFlexiVarTy, zonkQuantifiedTyVar,
tcInstSigType, zonkTcType, zonkTcTypes, zonkTcTyVar )
-import TcType ( TcTyVar, SkolemInfo(SigSkol),
+import TcType ( TcType, TcTyVar, SkolemInfo(SigSkol),
TcTauType, TcSigmaType, isUnboxedTupleType,
mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType,
mkForAllTy, isUnLiftedType, tcGetTyVar,
import Kind ( argTypeKind )
import VarEnv ( TyVarEnv, emptyVarEnv, lookupVarEnv, extendVarEnv, emptyTidyEnv )
import TysPrim ( alphaTyVar )
-import Id ( Id, mkLocalId, mkVanillaGlobal, mkSpecPragmaId, setInlinePragma )
+import Id ( Id, mkLocalId, mkVanillaGlobal )
import IdInfo ( vanillaIdInfo )
-import Var ( idType, idName )
+import Var ( TyVar, idType, idName )
import Name ( Name )
import NameSet
+import NameEnv
import VarSet
-import SrcLoc ( Located(..), unLoc, noLoc, getLoc )
+import SrcLoc ( Located(..), unLoc, getLoc )
import Bag
import ErrUtils ( Message )
-import Util ( isIn )
-import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec,
- isNotTopLevel, isAlwaysActive )
-import FiniteMap ( listToFM, lookupFM )
+import Digraph ( SCC(..), stronglyConnComp, flattenSCC )
+import Maybes ( fromJust, isJust, orElse )
+import Util ( singleton )
+import BasicTypes ( TopLevelFlag(..), isTopLevel, isNotTopLevel,
+ RecFlag(..), isNonRec )
import Outputable
\end{code}
dictionaries, which we resolve at the module level.
\begin{code}
-tcTopBinds :: [HsBindGroup Name] -> TcM (LHsBinds TcId, TcLclEnv)
+tcTopBinds :: HsValBinds Name -> TcM (LHsBinds TcId, TcLclEnv)
-- Note: returning the TcLclEnv is more than we really
-- want. The bit we care about is the local bindings
-- and the free type variables thereof
tcTopBinds binds
- = tc_binds_and_then TopLevel glue binds $
- do { env <- getLclEnv
- ; return (emptyLHsBinds, env) }
- where
+ = do { (ValBindsOut prs, env) <- tcValBinds TopLevel binds getLclEnv
+ ; return (foldr (unionBags . snd) emptyBag prs, env) }
-- The top level bindings are flattened into a giant
- -- implicitly-mutually-recursive MonoBinds
- glue (HsBindGroup binds1 _ _) (binds2, env) = (binds1 `unionBags` binds2, env)
- glue (HsIPBinds _) _ = panic "Top-level HsIpBinds"
- -- Can't have a HsIPBinds at top level
+ -- implicitly-mutually-recursive LHsBinds
-tcHsBootSigs :: [HsBindGroup Name] -> TcM [Id]
+tcHsBootSigs :: HsValBinds Name -> TcM [Id]
-- A hs-boot file has only one BindGroup, and it only has type
-- signatures in it. The renamer checked all this
-tcHsBootSigs [HsBindGroup binds sigs _]
+tcHsBootSigs (ValBindsIn binds sigs)
= do { checkTc (isEmptyLHsBinds binds) badBootDeclErr
; mapM (addLocM tc_boot_sig) (filter isVanillaLSig sigs) }
where
badBootDeclErr :: Message
badBootDeclErr = ptext SLIT("Illegal declarations in an hs-boot file")
-tcBindsAndThen
- :: (HsBindGroup TcId -> thing -> thing) -- Combinator
- -> [HsBindGroup Name]
- -> TcM thing
- -> TcM thing
+------------------------
+tcLocalBinds :: HsLocalBinds Name -> TcM thing
+ -> TcM (HsLocalBinds TcId, thing)
-tcBindsAndThen = tc_binds_and_then NotTopLevel
+tcLocalBinds EmptyLocalBinds thing_inside
+ = do { thing <- thing_inside
+ ; return (EmptyLocalBinds, thing) }
-tc_binds_and_then top_lvl combiner [] do_next
- = do_next
-tc_binds_and_then top_lvl combiner (group : groups) do_next
- = tc_bind_and_then top_lvl combiner group $
- tc_binds_and_then top_lvl combiner groups do_next
+tcLocalBinds (HsValBinds binds) thing_inside
+ = do { (binds', thing) <- tcValBinds NotTopLevel binds thing_inside
+ ; return (HsValBinds binds', thing) }
-tc_bind_and_then top_lvl combiner (HsIPBinds binds) do_next
- = getLIE do_next `thenM` \ (result, expr_lie) ->
- mapAndUnzipM (wrapLocSndM tc_ip_bind) binds `thenM` \ (avail_ips, binds') ->
+tcLocalBinds (HsIPBinds (IPBinds ip_binds _)) thing_inside
+ = do { (thing, lie) <- getLIE thing_inside
+ ; (avail_ips, ip_binds') <- mapAndUnzipM (wrapLocSndM tc_ip_bind) ip_binds
-- If the binding binds ?x = E, we must now
-- discharge any ?x constraints in expr_lie
- tcSimplifyIPs avail_ips expr_lie `thenM` \ dict_binds ->
-
- returnM (combiner (HsIPBinds binds') $
- combiner (HsBindGroup dict_binds [] Recursive) result)
+ ; dict_binds <- tcSimplifyIPs avail_ips lie
+ ; return (HsIPBinds (IPBinds ip_binds' dict_binds), thing) }
where
-- I wonder if we should do these one at at time
-- Consider ?x = 4
tcCheckRho expr ty `thenM` \ expr' ->
returnM (ip_inst, (IPBind ip' expr'))
-tc_bind_and_then top_lvl combiner (HsBindGroup binds sigs is_rec) do_next
- | isEmptyLHsBinds binds
- = do_next
- | otherwise
- = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE
+------------------------
+mkEdges :: (Name -> Bool) -> [LHsBind Name]
+ -> [(LHsBind Name, BKey, [BKey])]
+
+type BKey = Int -- Just number off the bindings
+
+mkEdges exclude_fn binds
+ = [ (bind, key, [fromJust mb_key | n <- nameSetToList (bind_fvs (unLoc bind)),
+ let mb_key = lookupNameEnv key_map n,
+ isJust mb_key,
+ not (exclude_fn n) ])
+ | (bind, key) <- keyd_binds
+ ]
+ where
+ keyd_binds = binds `zip` [0::BKey ..]
+
+ bind_fvs (FunBind _ _ _ fvs) = fvs
+ bind_fvs (PatBind _ _ _ fvs) = fvs
+ bind_fvs bind = pprPanic "mkEdges" (ppr bind)
+
+ key_map :: NameEnv BKey -- Which binding it comes from
+ key_map = mkNameEnv [(bndr, key) | (L _ bind, key) <- keyd_binds
+ , bndr <- bindersOfHsBind bind ]
+
+bindersOfHsBind :: HsBind Name -> [Name]
+bindersOfHsBind (PatBind pat _ _ _) = collectPatBinders pat
+bindersOfHsBind (FunBind (L _ f) _ _ _) = [f]
+
+------------------------
+tcValBinds :: TopLevelFlag
+ -> HsValBinds Name -> TcM thing
+ -> TcM (HsValBinds TcId, thing)
+
+tcValBinds top_lvl (ValBindsIn binds sigs) thing_inside
+ = tcAddLetBoundTyVars binds $
+ -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE
-- Notice that they scope over
-- a) the type signatures in the binding group
-- b) the bindings in the group
-- c) the scope of the binding group (the "in" part)
- tcAddLetBoundTyVars binds $
-
- case top_lvl of
- TopLevel -- For the top level don't bother will all this
- -- bindInstsOfLocalFuns stuff. All the top level
- -- things are rec'd together anyway, so it's fine to
- -- leave them to the tcSimplifyTop, and quite a bit faster too
- -> tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) ->
- tc_body poly_ids `thenM` \ (prag_binds, thing) ->
- returnM (combiner (HsBindGroup
- (poly_binds `unionBags` prag_binds)
- [] -- no sigs
- Recursive)
- thing)
-
- NotTopLevel -- For nested bindings we must do the bindInstsOfLocalFuns thing.
- | not (isRec is_rec) -- Non-recursive group
- -> -- We want to keep non-recursive things non-recursive
- -- so that we desugar unlifted bindings correctly
- tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) ->
- getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) ->
-
- -- Create specialisations of functions bound here
- bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds ->
-
- returnM (
- combiner (HsBindGroup poly_binds [] NonRecursive) $
- combiner (HsBindGroup prag_binds [] NonRecursive) $
- combiner (HsBindGroup lie_binds [] Recursive) $
- -- NB: the binds returned by tcSimplify and
- -- bindInstsOfLocalFuns aren't guaranteed in
- -- dependency order (though we could change that);
- -- hence the Recursive marker.
- thing)
-
- | otherwise
- -> -- NB: polymorphic recursion means that a function
- -- may use an instance of itself, we must look at the LIE arising
- -- from the function's own right hand side. Hence the getLIE
- -- encloses the tcBindWithSigs.
-
- getLIE (
- tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) ->
- tc_body poly_ids `thenM` \ (prag_binds, thing) ->
- returnM (poly_ids, poly_binds `unionBags` prag_binds, thing)
- ) `thenM` \ ((poly_ids, extra_binds, thing), lie) ->
- bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds ->
+ do { -- Typecheck the signature
+ tc_ty_sigs <- recoverM (returnM []) (tcTySigs sigs)
- returnM (combiner (HsBindGroup
- (extra_binds `unionBags` lie_binds)
- [] Recursive) thing
- )
- where
- tc_body poly_ids -- Type check the pragmas and "thing inside"
- = -- Extend the environment to bind the new polymorphic Ids
- tcExtendIdEnv poly_ids $
-
- -- Build bindings and IdInfos corresponding to user pragmas
- tcSpecSigs sigs `thenM` \ prag_binds ->
+ -- Do the basic strongly-connected component thing
+ ; let { sccs :: [SCC (LHsBind Name)]
+ ; sccs = stronglyConnComp (mkEdges (\n -> False) (bagToList binds))
+ ; prag_fn = mkPragFun sigs
+ ; sig_fn = lookupSig tc_ty_sigs
+ ; sig_ids = map sig_id tc_ty_sigs }
- -- Now do whatever happens next, in the augmented envt
- do_next `thenM` \ thing ->
-
- returnM (prag_binds, thing)
-\end{code}
+ -- Extend the envt right away with all
+ -- the Ids declared with type signatures
+ ; (binds', thing) <- tcExtendIdEnv sig_ids $
+ tc_val_binds top_lvl sig_fn prag_fn
+ sccs thing_inside
+ ; return (ValBindsOut binds', thing) }
-%************************************************************************
-%* *
-\subsection{tcBindWithSigs}
-%* *
-%************************************************************************
-
-@tcBindWithSigs@ deals with a single binding group. It does generalisation,
-so all the clever stuff is in here.
+------------------------
+tc_val_binds :: TopLevelFlag -> TcSigFun -> TcPragFun
+ -> [SCC (LHsBind Name)] -> TcM thing
+ -> TcM ([(RecFlag, LHsBinds TcId)], thing)
+-- Typecheck a whole lot of value bindings,
+-- one strongly-connected component at a time
+
+tc_val_binds top_lvl sig_fn prag_fn [] thing_inside
+ = do { thing <- thing_inside
+ ; return ([], thing) }
+
+tc_val_binds top_lvl sig_fn prag_fn (scc : sccs) thing_inside
+ = do { (group', (groups', thing))
+ <- tc_group top_lvl sig_fn prag_fn scc $
+ tc_val_binds top_lvl sig_fn prag_fn sccs thing_inside
+ ; return (group' ++ groups', thing) }
-* binder_names and mbind must define the same set of Names
+------------------------
+tc_group :: TopLevelFlag -> TcSigFun -> TcPragFun
+ -> SCC (LHsBind Name) -> TcM thing
+ -> TcM ([(RecFlag, LHsBinds TcId)], thing)
+
+-- Typecheck one strongly-connected component of the original program.
+-- We get a list of groups back, because there may
+-- be specialisations etc as well
+
+tc_group top_lvl sig_fn prag_fn scc@(AcyclicSCC bind) thing_inside
+ = -- A single non-recursive binding
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unlifted bindings correctly
+ do { (binds, thing) <- tcPolyBinds top_lvl NonRecursive
+ sig_fn prag_fn scc thing_inside
+ ; return ([(NonRecursive, b) | b <- binds], thing) }
+
+tc_group top_lvl sig_fn prag_fn (CyclicSCC binds) thing_inside
+ = -- A recursive strongly-connected component
+ -- To maximise polymorphism, we do a new strongly-connected
+ -- component analysis, this time omitting any references to
+ -- variables with type signatures.
+ --
+ -- Then we bring into scope all the variables with type signatures
+ do { traceTc (text "tc_group rec" <+> vcat [ppr b $$ text "--and--" | b <- binds])
+ ; let { sccs :: [SCC (LHsBind Name)]
+ ; sccs = stronglyConnComp (mkEdges has_sig binds) }
+ ; (binds, thing) <- go sccs
+ ; return ([(Recursive, unionManyBags binds)], thing) }
+ -- Rec them all together
+ where
+-- go :: SCC (LHsBind Name) -> TcM ([LHsBind TcId], thing)
+ go (scc:sccs) = do { (binds1, (binds2, thing)) <- go1 scc (go sccs)
+ ; return (binds1 ++ binds2, thing) }
+ go [] = do { thing <- thing_inside; return ([], thing) }
-* The Names in tc_ty_sigs must be a subset of binder_names
+ go1 scc thing_inside = tcPolyBinds top_lvl Recursive
+ sig_fn prag_fn scc thing_inside
-* The Ids in tc_ty_sigs don't necessarily have to have the same name
- as the Name in the tc_ty_sig
+ has_sig :: Name -> Bool
+ has_sig n = isJust (sig_fn n)
-\begin{code}
-tcBindWithSigs :: TopLevelFlag
- -> LHsBinds Name
- -> [LSig Name]
- -> RecFlag
- -> TcM (LHsBinds TcId, [TcId])
- -- The returned TcIds are guaranteed zonked
-
-tcBindWithSigs top_lvl mbind sigs is_rec = do
- { -- TYPECHECK THE SIGNATURES
- tc_ty_sigs <- recoverM (returnM []) $
- tcTySigs (filter isVanillaLSig sigs)
- ; let lookup_sig = lookupSig tc_ty_sigs
+------------------------
+tcPolyBinds :: TopLevelFlag -> RecFlag
+ -> TcSigFun -> TcPragFun
+ -> SCC (LHsBind Name)
+ -> TcM thing
+ -> TcM ([LHsBinds TcId], thing)
+
+-- Typechecks a single bunch of bindings all together,
+-- and generalises them. The bunch may be only part of a recursive
+-- group, because we use type signatures to maximise polymorphism
+--
+-- Deals with the bindInstsOfLocalFuns thing too
+
+tcPolyBinds top_lvl is_rec sig_fn prag_fn scc thing_inside
+ = -- NB: polymorphic recursion means that a function
+ -- may use an instance of itself, we must look at the LIE arising
+ -- from the function's own right hand side. Hence the getLIE
+ -- encloses the tc_poly_binds.
+ do { traceTc (text "tcPolyBinds" <+> ppr scc)
+ ; ((binds1, poly_ids, thing), lie) <- getLIE $
+ do { (binds1, poly_ids) <- tc_poly_binds top_lvl is_rec
+ sig_fn prag_fn scc
+ ; thing <- tcExtendIdEnv poly_ids thing_inside
+ ; return (binds1, poly_ids, thing) }
+
+ ; if isTopLevel top_lvl
+ then -- For the top level don't bother will all this
+ -- bindInstsOfLocalFuns stuff. All the top level
+ -- things are rec'd together anyway, so it's fine to
+ -- leave them to the tcSimplifyTop,
+ -- and quite a bit faster too
+ do { extendLIEs lie; return (binds1, thing) }
+
+ else do -- Nested case
+ { lie_binds <- bindInstsOfLocalFuns lie poly_ids
+ ; return (binds1 ++ [lie_binds], thing) }}
+------------------------
+tc_poly_binds :: TopLevelFlag -> RecFlag
+ -> TcSigFun -> TcPragFun
+ -> SCC (LHsBind Name)
+ -> TcM ([LHsBinds TcId], [TcId])
+-- Typechecks the bindings themselves
+-- Knows nothing about the scope of the bindings
+
+tc_poly_binds top_lvl is_rec sig_fn prag_fn bind_scc
+ = let
+ non_rec = case bind_scc of { AcyclicSCC _ -> True; CyclicSCC _ -> False }
+ binds = flattenSCC bind_scc
+ binder_names = collectHsBindBinders (listToBag binds)
+
+ loc = getLoc (head binds)
+ -- TODO: location a bit awkward, but the mbinds have been
+ -- dependency analysed and may no longer be adjacent
+ in
-- SET UP THE MAIN RECOVERY; take advantage of any type sigs
- ; recoverM (recoveryCode mbind lookup_sig) $ do
+ setSrcSpan loc $
+ recoverM (recoveryCode binder_names sig_fn) $ do
- { traceTc (ptext SLIT("--------------------------------------------------------"))
- ; traceTc (ptext SLIT("Bindings for") <+> ppr (collectHsBindBinders mbind))
+ { traceTc (ptext SLIT("------------------------------------------------"))
+ ; traceTc (ptext SLIT("Bindings for") <+> ppr binder_names)
-- TYPECHECK THE BINDINGS
- ; ((mbind', mono_bind_infos), lie_req)
- <- getLIE (tcMonoBinds mbind lookup_sig is_rec)
+ ; ((binds', mono_bind_infos), lie_req)
+ <- getLIE (tcMonoBinds binds sig_fn non_rec)
-- CHECK FOR UNLIFTED BINDINGS
-- These must be non-recursive etc, and are not generalised
; zonked_mono_tys <- zonkTcTypes (map getMonoType mono_bind_infos)
; if any isUnLiftedType zonked_mono_tys then
do { -- Unlifted bindings
- checkUnliftedBinds top_lvl is_rec mbind
+ checkUnliftedBinds top_lvl is_rec binds' mono_bind_infos
; extendLIEs lie_req
; let exports = zipWith mk_export mono_bind_infos zonked_mono_tys
- mk_export (name, Nothing, mono_id) mono_ty = ([], mkLocalId name mono_ty, mono_id)
- mk_export (name, Just sig, mono_id) mono_ty = ([], sig_id sig, mono_id)
+ mk_export (name, Nothing, mono_id) mono_ty = ([], mkLocalId name mono_ty, mono_id, [])
+ mk_export (name, Just sig, mono_id) mono_ty = ([], sig_id sig, mono_id, [])
+ -- ToDo: prags
- ; return ( unitBag $ noLoc $ AbsBinds [] [] exports emptyNameSet mbind',
- [poly_id | (_, poly_id, _) <- exports]) } -- Guaranteed zonked
+ ; return ( [unitBag $ L loc $ AbsBinds [] [] exports binds'],
+ [poly_id | (_, poly_id, _, _) <- exports]) } -- Guaranteed zonked
else do -- The normal lifted case: GENERALISE
- { is_unres <- isUnRestrictedGroup mbind tc_ty_sigs
+ { is_unres <- isUnRestrictedGroup binds sig_fn
; (tyvars_to_gen, dict_binds, dict_ids)
- <- setSrcSpan (getLoc (head (bagToList mbind))) $
- -- TODO: location a bit awkward, but the mbinds have been
- -- dependency analysed and may no longer be adjacent
- addErrCtxt (genCtxt (bndrNames mono_bind_infos)) $
- generalise top_lvl is_unres mono_bind_infos tc_ty_sigs lie_req
+ <- addErrCtxt (genCtxt (bndrNames mono_bind_infos)) $
+ generalise top_lvl is_unres mono_bind_infos lie_req
-- FINALISE THE QUANTIFIED TYPE VARIABLES
-- The quantified type variables often include meta type variables
; tyvars_to_gen' <- mappM zonkQuantifiedTyVar tyvars_to_gen
-- BUILD THE POLYMORPHIC RESULT IDs
- ; let
- exports = map mk_export mono_bind_infos
- poly_ids = [poly_id | (_, poly_id, _) <- exports]
- dict_tys = map idType dict_ids
-
- inlines = mkNameSet [ name
- | L _ (InlineSig True (L _ name) _) <- sigs]
- -- Any INLINE sig (regardless of phase control)
- -- makes the RHS look small
- inline_phases = listToFM [ (name, phase)
- | L _ (InlineSig _ (L _ name) phase) <- sigs,
- not (isAlwaysActive phase)]
- -- Set the IdInfo field to control the inline phase
- -- AlwaysActive is the default, so don't bother with them
- add_inlines id = attachInlinePhase inline_phases id
-
- mk_export (binder_name, mb_sig, mono_id)
- = case mb_sig of
- Just sig -> (sig_tvs sig, add_inlines (sig_id sig), mono_id)
- Nothing -> (tyvars_to_gen', add_inlines new_poly_id, mono_id)
- where
- new_poly_id = mkLocalId binder_name poly_ty
- poly_ty = mkForAllTys tyvars_to_gen'
- $ mkFunTys dict_tys
- $ idType mono_id
+ ; exports <- mapM (mkExport prag_fn tyvars_to_gen' (map idType dict_ids))
+ mono_bind_infos
-- ZONK THE poly_ids, because they are used to extend the type
-- environment; see the invariant on TcEnv.tcExtendIdEnv
+ ; let poly_ids = [poly_id | (_, poly_id, _, _) <- exports]
; zonked_poly_ids <- mappM zonkId poly_ids
; traceTc (text "binding:" <+> ppr ((dict_ids, dict_binds),
- exports, map idType zonked_poly_ids))
-
- ; return (
- unitBag $ noLoc $
- AbsBinds tyvars_to_gen'
- dict_ids
- exports
- inlines
- (dict_binds `unionBags` mbind'),
- zonked_poly_ids
- )
- } } }
+ map idType zonked_poly_ids))
+
+ ; let abs_bind = L loc $ AbsBinds tyvars_to_gen'
+ dict_ids exports
+ (dict_binds `unionBags` binds')
+
+ ; return ([unitBag abs_bind], zonked_poly_ids)
+ } }
+
+
+--------------
+mkExport :: TcPragFun -> [TyVar] -> [TcType] -> MonoBindInfo
+ -> TcM ([TyVar], Id, Id, [Prag])
+mkExport prag_fn inferred_tvs dict_tys (poly_name, mb_sig, mono_id)
+ = do { prags <- tcPrags poly_id (prag_fn poly_name)
+ ; return (tvs, poly_id, mono_id, prags) }
+ where
+ (tvs, poly_id) = case mb_sig of
+ Just sig -> (sig_tvs sig, sig_id sig)
+ Nothing -> (inferred_tvs, mkLocalId poly_name poly_ty)
+ where
+ poly_ty = mkForAllTys inferred_tvs
+ $ mkFunTys dict_tys
+ $ idType mono_id
+
+------------------------
+type TcPragFun = Name -> [LSig Name]
+
+mkPragFun :: [LSig Name] -> TcPragFun
+mkPragFun sigs = \n -> lookupNameEnv env n `orElse` []
+ where
+ prs = [(fromJust (sigName sig), sig) | sig <- sigs, isPragLSig sig]
+ env = foldl add emptyNameEnv prs
+ add env (n,p) = extendNameEnv_Acc (:) singleton env n p
+
+tcPrags :: Id -> [LSig Name] -> TcM [Prag]
+tcPrags poly_id prags = mapM tc_prag prags
+ where
+ tc_prag (L loc prag) = setSrcSpan loc $
+ addErrCtxt (pragSigCtxt prag) $
+ tcPrag poly_id prag
+
+pragSigCtxt prag = hang (ptext SLIT("In the pragma")) 2 (ppr prag)
+
+tcPrag :: TcId -> Sig Name -> TcM Prag
+tcPrag poly_id (SpecSig orig_name hs_ty) = tcSpecPrag poly_id hs_ty
+tcPrag poly_id (SpecInstSig hs_ty) = tcSpecPrag poly_id hs_ty
+tcPrag poly_id (InlineSig inl _ act) = return (InlinePrag inl act)
+
+tcSpecPrag :: TcId -> LHsType Name -> TcM Prag
+tcSpecPrag poly_id hs_ty
+ = do { spec_ty <- tcHsSigType (FunSigCtxt (idName poly_id)) hs_ty
+ ; (co_fn, lie) <- getLIE (tcSub spec_ty (idType poly_id))
+ ; extendLIEs lie
+ ; let const_dicts = map instToId lie
+ ; return (SpecPrag (co_fn <$> (HsVar poly_id)) spec_ty const_dicts) }
+
+--------------
-- If typechecking the binds fails, then return with each
-- signature-less binder given type (forall a.a), to minimise
-- subsequent error messages
-recoveryCode mbind lookup_sig
+recoveryCode binder_names sig_fn
= do { traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names)
- ; return (emptyLHsBinds, poly_ids) }
+ ; return ([], poly_ids) }
where
forall_a_a = mkForAllTy alphaTyVar (mkTyVarTy alphaTyVar)
- binder_names = collectHsBindBinders mbind
poly_ids = map mk_dummy binder_names
- mk_dummy name = case lookup_sig name of
+ mk_dummy name = case sig_fn name of
Just sig -> sig_id sig -- Signature
Nothing -> mkLocalId name forall_a_a -- No signature
-attachInlinePhase inline_phases bndr
- = case lookupFM inline_phases (idName bndr) of
- Just prag -> bndr `setInlinePragma` prag
- Nothing -> bndr
-
-- Check that non-overloaded unlifted bindings are
-- a) non-recursive,
-- b) not top level,
-- c) not a multiple-binding group (more or less implied by (a))
-checkUnliftedBinds top_lvl is_rec mbind
- = checkTc (isNotTopLevel top_lvl)
- (unliftedBindErr "Top-level" mbind) `thenM_`
- checkTc (isNonRec is_rec)
- (unliftedBindErr "Recursive" mbind) `thenM_`
- checkTc (isSingletonBag mbind)
- (unliftedBindErr "Multiple" mbind)
+checkUnliftedBinds :: TopLevelFlag -> RecFlag
+ -> LHsBinds TcId -> [MonoBindInfo] -> TcM ()
+checkUnliftedBinds top_lvl is_rec mbind infos
+ = do { checkTc (isNotTopLevel top_lvl)
+ (unliftedBindErr "Top-level" mbind)
+ ; checkTc (isNonRec is_rec)
+ (unliftedBindErr "Recursive" mbind)
+ ; checkTc (isSingletonBag mbind)
+ (unliftedBindErr "Multiple" mbind)
+ ; mapM_ check_sig infos }
+ where
+ check_sig (_, Just sig, _) = checkTc (null (sig_tvs sig) && null (sig_theta sig))
+ (badUnliftedSig sig)
+ check_sig other = return ()
\end{code}
-Polymorphic recursion
-~~~~~~~~~~~~~~~~~~~~~
-The game plan for polymorphic recursion in the code above is
-
- * Bind any variable for which we have a type signature
- to an Id with a polymorphic type. Then when type-checking
- the RHSs we'll make a full polymorphic call.
-
-This fine, but if you aren't a bit careful you end up with a horrendous
-amount of partial application and (worse) a huge space leak. For example:
-
- f :: Eq a => [a] -> [a]
- f xs = ...f...
-
-If we don't take care, after typechecking we get
-
- f = /\a -> \d::Eq a -> let f' = f a d
- in
- \ys:[a] -> ...f'...
-
-Notice the the stupid construction of (f a d), which is of course
-identical to the function we're executing. In this case, the
-polymorphic recursion isn't being used (but that's a very common case).
-We'd prefer
-
- f = /\a -> \d::Eq a -> letrec
- fm = \ys:[a] -> ...fm...
- in
- fm
-
-This can lead to a massive space leak, from the following top-level defn
-(post-typechecking)
-
- ff :: [Int] -> [Int]
- ff = f Int dEqInt
-
-Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but
-f' is another thunk which evaluates to the same thing... and you end
-up with a chain of identical values all hung onto by the CAF ff.
-
- ff = f Int dEqInt
-
- = let f' = f Int dEqInt in \ys. ...f'...
-
- = let f' = let f' = f Int dEqInt in \ys. ...f'...
- in \ys. ...f'...
-
-Etc.
-Solution: when typechecking the RHSs we always have in hand the
-*monomorphic* Ids for each binding. So we just need to make sure that
-if (Method f a d) shows up in the constraints emerging from (...f...)
-we just use the monomorphic Id. We achieve this by adding monomorphic Ids
-to the "givens" when simplifying constraints. That's what the "lies_avail"
-is doing.
-
-
%************************************************************************
%* *
\subsection{tcMonoBind}
%* *
%************************************************************************
-@tcMonoBinds@ deals with a single @MonoBind@.
+@tcMonoBinds@ deals with a perhaps-recursive group of HsBinds.
The signatures have been dealt with already.
\begin{code}
-tcMonoBinds :: LHsBinds Name
- -> TcSigFun -> RecFlag
+tcMonoBinds :: [LHsBind Name]
+ -> TcSigFun
+ -> Bool -- True <=> either the binders are not mentioned
+ -- in their RHSs or they have type sigs
-> TcM (LHsBinds TcId, [MonoBindInfo])
-tcMonoBinds binds lookup_sig is_rec
- | isNonRec is_rec, -- Non-recursive, single function binding
- [L b_loc (FunBind (L nm_loc name) inf matches)] <- bagToList binds,
- Nothing <- lookup_sig name -- ...with no type signature
+tcMonoBinds [L b_loc (FunBind (L nm_loc name) inf matches fvs)]
+ sig_fn -- Single function binding,
+ True -- binder isn't mentioned in RHS,
+ | Nothing <- sig_fn name -- ...with no type signature
= -- In this very special case we infer the type of the
-- right hand side first (it may have a higher-rank type)
-- and *then* make the monomorphic Id for the LHS
-- We want to infer a higher-rank type for f
setSrcSpan b_loc $
do { (matches', rhs_ty) <- tcInfer (tcMatchesFun name matches)
+
-- Check for an unboxed tuple type
-- f = (# True, False #)
-- Zonk first just in case it's hidden inside a meta type variable
; zonked_rhs_ty <- zonkTcType rhs_ty
; checkTc (not (isUnboxedTupleType zonked_rhs_ty))
(unboxedTupleErr name zonked_rhs_ty)
+
; mono_name <- newLocalName name
; let mono_id = mkLocalId mono_name zonked_rhs_ty
- ; return (unitBag (L b_loc (FunBind (L nm_loc mono_id) inf matches')),
+ ; return (unitBag (L b_loc (FunBind (L nm_loc mono_id) inf matches' fvs)),
[(name, Nothing, mono_id)]) }
- | otherwise
- = do { tc_binds <- mapBagM (wrapLocM (tcLhs lookup_sig)) binds
+tcMonoBinds binds sig_fn non_rec
+ = do { tc_binds <- mapM (wrapLocM (tcLhs sig_fn)) binds
-- Bring (a) the scoped type variables, and (b) the Ids, into scope for the RHSs
-- For (a) it's ok to bring them all into scope at once, even
; binds' <- tcExtendTyVarEnv2 rhs_tvs $
tcExtendIdEnv2 rhs_id_env $
- traceTc (text "tcMonoBinds" <+> vcat [ppr n <+> ppr id <+> ppr (idType id) | (n,id) <- rhs_id_env]) `thenM_`
- mapBagM (wrapLocM tcRhs) tc_binds
- ; return (binds', mono_info) }
+ traceTc (text "tcMonoBinds" <+> vcat [ ppr n <+> ppr id <+> ppr (idType id)
+ | (n,id) <- rhs_id_env]) `thenM_`
+ mapM (wrapLocM tcRhs) tc_binds
+ ; return (listToBag binds', mono_info) }
where
mk (name, Just sig, _) = (name, sig_id sig) -- Use the type sig if there is one
mk (name, Nothing, mono_id) = (name, mono_id) -- otherwise use a monomorphic version
getMonoType (_,_,mono_id) = idType mono_id
tcLhs :: TcSigFun -> HsBind Name -> TcM TcMonoBind
-tcLhs lookup_sig (FunBind (L nm_loc name) inf matches)
- = do { let mb_sig = lookup_sig name
+tcLhs sig_fn (FunBind (L nm_loc name) inf matches _)
+ = do { let mb_sig = sig_fn name
; mono_name <- newLocalName name
; mono_ty <- mk_mono_ty mb_sig
; let mono_id = mkLocalId mono_name mono_ty
mk_mono_ty (Just sig) = return (sig_tau sig)
mk_mono_ty Nothing = newTyFlexiVarTy argTypeKind
-tcLhs lookup_sig bind@(PatBind pat grhss _)
- = do { let tc_pat exp_ty = tcPat (LetPat lookup_sig) pat exp_ty lookup_infos
+tcLhs sig_fn bind@(PatBind pat grhss _ _)
+ = do { let tc_pat exp_ty = tcPat (LetPat sig_fn) pat exp_ty lookup_infos
; ((pat', ex_tvs, infos), pat_ty)
<- addErrCtxt (patMonoBindsCtxt pat grhss)
(tcInfer tc_pat)
-- names, which the pattern has brought into scope.
lookup_infos :: TcM [MonoBindInfo]
lookup_infos = do { mono_ids <- tcLookupLocalIds names
- ; return [ (name, lookup_sig name, mono_id)
+ ; return [ (name, sig_fn name, mono_id)
| (name, mono_id) <- names `zip` mono_ids] }
-tcLhs lookup_sig other_bind = pprPanic "tcLhs" (ppr other_bind)
+tcLhs sig_fn other_bind = pprPanic "tcLhs" (ppr other_bind)
-- AbsBind, VarBind impossible
-------------------
tcRhs (TcFunBind info fun'@(L _ mono_id) inf matches)
= do { matches' <- tcMatchesFun (idName mono_id) matches
(Check (idType mono_id))
- ; return (FunBind fun' inf matches') }
+ ; return (FunBind fun' inf matches' placeHolderNames) }
tcRhs bind@(TcPatBind _ pat' grhss pat_ty)
= do { grhss' <- addErrCtxt (patMonoBindsCtxt pat' grhss) $
tcGRHSsPat grhss (Check pat_ty)
- ; return (PatBind pat' grhss' pat_ty) }
+ ; return (PatBind pat' grhss' pat_ty placeHolderNames) }
---------------------
-getMonoBindInfo :: Bag (Located TcMonoBind) -> [MonoBindInfo]
+getMonoBindInfo :: [Located TcMonoBind] -> [MonoBindInfo]
getMonoBindInfo tc_binds
- = foldrBag (get_info . unLoc) [] tc_binds
+ = foldr (get_info . unLoc) [] tc_binds
where
get_info (TcFunBind info _ _ _) rest = info : rest
get_info (TcPatBind infos _ _ _) rest = infos ++ rest
%************************************************************************
%* *
-\subsection{getTyVarsToGen}
+ Generalisation
%* *
%************************************************************************
-Type signatures are tricky. See Note [Signature skolems] in TcType
-
\begin{code}
-tcTySigs :: [LSig Name] -> TcM [TcSigInfo]
--- The trick here is that all the signatures should have the same
--- context, and we want to share type variables for that context, so that
--- all the right hand sides agree a common vocabulary for their type
--- constraints
-tcTySigs [] = return []
-
-tcTySigs sigs
- = do { (tc_sig1 : tc_sigs) <- mappM tcTySig sigs
- ; mapM (check_ctxt tc_sig1) tc_sigs
- ; return (tc_sig1 : tc_sigs) }
- where
- -- Check tha all the signature contexts are the same
- -- The type signatures on a mutually-recursive group of definitions
- -- must all have the same context (or none).
- --
- -- We unify them because, with polymorphic recursion, their types
- -- might not otherwise be related. This is a rather subtle issue.
- check_ctxt :: TcSigInfo -> TcSigInfo -> TcM ()
- check_ctxt sig1@(TcSigInfo { sig_theta = theta1 }) sig@(TcSigInfo { sig_theta = theta })
- = setSrcSpan (instLocSrcSpan (sig_loc sig)) $
- addErrCtxt (sigContextsCtxt sig1 sig) $
- unifyTheta theta1 theta
-
-
-tcTySig :: LSig Name -> TcM TcSigInfo
-tcTySig (L span (Sig (L _ name) ty))
- = setSrcSpan span $
- do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty
- ; (tvs, theta, tau) <- tcInstSigType name scoped_names sigma_ty
- ; loc <- getInstLoc (SigOrigin (SigSkol name))
- ; return (TcSigInfo { sig_id = mkLocalId name sigma_ty,
- sig_tvs = tvs, sig_theta = theta, sig_tau = tau,
- sig_scoped = scoped_names, sig_loc = loc }) }
- where
- -- The scoped names are the ones explicitly mentioned
- -- in the HsForAll. (There may be more in sigma_ty, because
- -- of nested type synonyms. See Note [Scoped] with TcSigInfo.)
- scoped_names = case ty of
- L _ (HsForAllTy Explicit tvs _ _) -> hsLTyVarNames tvs
- other -> []
-\end{code}
-
-\begin{code}
-generalise :: TopLevelFlag -> Bool -> [MonoBindInfo] -> [TcSigInfo] -> [Inst]
+generalise :: TopLevelFlag -> Bool
+ -> [MonoBindInfo] -> [Inst]
-> TcM ([TcTyVar], TcDictBinds, [TcId])
-generalise top_lvl is_unrestricted mono_infos sigs lie_req
+generalise top_lvl is_unrestricted mono_infos lie_req
| not is_unrestricted -- RESTRICTED CASE
= -- Check signature contexts are empty
do { checkTc (all is_mono_sig sigs)
- (restrictedBindCtxtErr bndr_names)
+ (restrictedBindCtxtErr bndrs)
-- Now simplify with exactly that set of tyvars
-- We have to squash those Methods
- ; (qtvs, binds) <- tcSimplifyRestricted doc top_lvl bndr_names
+ ; (qtvs, binds) <- tcSimplifyRestricted doc top_lvl bndrs
tau_tvs lie_req
-- Check that signature type variables are OK
= tcSimplifyInfer doc tau_tvs lie_req
| otherwise -- UNRESTRICTED CASE, WITH TYPE SIGS
- = do { let sig1 = head sigs
- ; sig_lie <- newDictsAtLoc (sig_loc sig1) (sig_theta sig1)
+ = do { sig_lie <- unifyCtxts sigs -- sigs is non-empty
; let -- The "sig_avails" is the stuff available. We get that from
-- the context of the type signature, BUT ALSO the lie_avail
- -- so that polymorphic recursion works right (see comments at end of fn)
+ -- so that polymorphic recursion works right (see Note [Polymorphic recursion])
local_meths = [mkMethInst sig mono_id | (_, Just sig, mono_id) <- mono_infos]
sig_avails = sig_lie ++ local_meths
; final_qtvs <- checkSigsTyVars forall_tvs sigs
; returnM (final_qtvs, dict_binds, map instToId sig_lie) }
-
where
- bndr_names = bndrNames mono_infos
+ bndrs = bndrNames mono_infos
+ sigs = [sig | (_, Just sig, _) <- mono_infos]
tau_tvs = foldr (unionVarSet . tyVarsOfType . getMonoType) emptyVarSet mono_infos
is_mono_sig sig = null (sig_theta sig)
- doc = ptext SLIT("type signature(s) for") <+> pprBinders bndr_names
+ doc = ptext SLIT("type signature(s) for") <+> pprBinders bndrs
mkMethInst (TcSigInfo { sig_id = poly_id, sig_tvs = tvs,
sig_theta = theta, sig_tau = tau, sig_loc = loc }) mono_id
= Method mono_id poly_id (mkTyVarTys tvs) theta tau loc
+
+-- Check that all the signature contexts are the same
+-- The type signatures on a mutually-recursive group of definitions
+-- must all have the same context (or none).
+--
+-- The trick here is that all the signatures should have the same
+-- context, and we want to share type variables for that context, so that
+-- all the right hand sides agree a common vocabulary for their type
+-- constraints
+--
+-- We unify them because, with polymorphic recursion, their types
+-- might not otherwise be related. This is a rather subtle issue.
+unifyCtxts :: [TcSigInfo] -> TcM [Inst]
+unifyCtxts (sig1 : sigs) -- Argument is always non-empty
+ = do { mapM unify_ctxt sigs
+ ; newDictsAtLoc (sig_loc sig1) (sig_theta sig1) }
+ where
+ theta1 = sig_theta sig1
+ unify_ctxt :: TcSigInfo -> TcM ()
+ unify_ctxt sig@(TcSigInfo { sig_theta = theta })
+ = setSrcSpan (instLocSrcSpan (sig_loc sig)) $
+ addErrCtxt (sigContextsCtxt sig1 sig) $
+ unifyTheta theta1 theta
+
checkSigsTyVars :: [TcTyVar] -> [TcSigInfo] -> TcM [TcTyVar]
checkSigsTyVars qtvs sigs
= do { gbl_tvs <- tcGetGlobalTyVars
constrained tyvars. We don't use any of the results, except to
find which tyvars are constrained.
-\begin{code}
-isUnRestrictedGroup :: LHsBinds Name -> [TcSigInfo] -> TcM Bool
-isUnRestrictedGroup binds sigs
- = do { mono_restriction <- doptM Opt_MonomorphismRestriction
- ; return (not mono_restriction || all_unrestricted) }
- where
- all_unrestricted = all (unrestricted . unLoc) (bagToList binds)
- tysig_names = map (idName . sig_id) sigs
+Note [Polymorphic recursion]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The game plan for polymorphic recursion in the code above is
- unrestricted (PatBind other _ _) = False
- unrestricted (VarBind v _) = v `is_elem` tysig_names
- unrestricted (FunBind v _ matches) = unrestricted_match matches
- || unLoc v `is_elem` tysig_names
+ * Bind any variable for which we have a type signature
+ to an Id with a polymorphic type. Then when type-checking
+ the RHSs we'll make a full polymorphic call.
- unrestricted_match (MatchGroup (L _ (Match [] _ _) : _) _) = False
- -- No args => like a pattern binding
- unrestricted_match other = True
- -- Some args => a function binding
+This fine, but if you aren't a bit careful you end up with a horrendous
+amount of partial application and (worse) a huge space leak. For example:
-is_elem v vs = isIn "isUnResMono" v vs
-\end{code}
+ f :: Eq a => [a] -> [a]
+ f xs = ...f...
+
+If we don't take care, after typechecking we get
+
+ f = /\a -> \d::Eq a -> let f' = f a d
+ in
+ \ys:[a] -> ...f'...
+
+Notice the the stupid construction of (f a d), which is of course
+identical to the function we're executing. In this case, the
+polymorphic recursion isn't being used (but that's a very common case).
+We'd prefer
+
+ f = /\a -> \d::Eq a -> letrec
+ fm = \ys:[a] -> ...fm...
+ in
+ fm
+
+This can lead to a massive space leak, from the following top-level defn
+(post-typechecking)
+
+ ff :: [Int] -> [Int]
+ ff = f Int dEqInt
+
+Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but
+f' is another thunk which evaluates to the same thing... and you end
+up with a chain of identical values all hung onto by the CAF ff.
+
+ ff = f Int dEqInt
+
+ = let f' = f Int dEqInt in \ys. ...f'...
+
+ = let f' = let f' = f Int dEqInt in \ys. ...f'...
+ in \ys. ...f'...
+
+Etc.
+Solution: when typechecking the RHSs we always have in hand the
+*monomorphic* Ids for each binding. So we just need to make sure that
+if (Method f a d) shows up in the constraints emerging from (...f...)
+we just use the monomorphic Id. We achieve this by adding monomorphic Ids
+to the "givens" when simplifying constraints. That's what the "lies_avail"
+is doing.
%************************************************************************
%* *
-\subsection{SPECIALIZE pragmas}
+ Signatures
%* *
%************************************************************************
-@tcSpecSigs@ munches up the specialisation "signatures" that arise through *user*
-pragmas. It is convenient for them to appear in the @[RenamedSig]@
-part of a binding because then the same machinery can be used for
-moving them into place as is done for type signatures.
-
-They look like this:
-
-\begin{verbatim}
- f :: Ord a => [a] -> b -> b
- {-# SPECIALIZE f :: [Int] -> b -> b #-}
-\end{verbatim}
-
-For this we generate:
-\begin{verbatim}
- f* = /\ b -> let d1 = ...
- in f Int b d1
-\end{verbatim}
-
-where f* is a SpecPragmaId. The **sole** purpose of SpecPragmaIds is to
-retain a right-hand-side that the simplifier will otherwise discard as
-dead code... the simplifier has a flag that tells it not to discard
-SpecPragmaId bindings.
-
-In this case the f* retains a call-instance of the overloaded
-function, f, (including appropriate dictionaries) so that the
-specialiser will subsequently discover that there's a call of @f@ at
-Int, and will create a specialisation for @f@. After that, the
-binding for @f*@ can be discarded.
-
-We used to have a form
- {-# SPECIALISE f :: <type> = g #-}
-which promised that g implemented f at <type>, but we do that with
-a RULE now:
- {-# RULES (f::<type>) = g #-}
+Type signatures are tricky. See Note [Signature skolems] in TcType
\begin{code}
-tcSpecSigs :: [LSig Name] -> TcM (LHsBinds TcId)
-tcSpecSigs (L loc (SpecSig (L nm_loc name) poly_ty) : sigs)
- = -- SPECIALISE f :: forall b. theta => tau = g
- setSrcSpan loc $
- addErrCtxt (valSpecSigCtxt name poly_ty) $
-
- -- Get and instantiate its alleged specialised type
- tcHsSigType (FunSigCtxt name) poly_ty `thenM` \ sig_ty ->
-
- -- Check that f has a more general type, and build a RHS for
- -- the spec-pragma-id at the same time
- getLIE (tcCheckSigma (L nm_loc (HsVar name)) sig_ty) `thenM` \ (spec_expr, spec_lie) ->
-
- -- Squeeze out any Methods (see comments with tcSimplifyToDicts)
- tcSimplifyToDicts spec_lie `thenM` \ spec_binds ->
-
- -- Just specialise "f" by building a SpecPragmaId binding
- -- It is the thing that makes sure we don't prematurely
- -- dead-code-eliminate the binding we are really interested in.
- newLocalName name `thenM` \ spec_name ->
- let
- spec_bind = VarBind (mkSpecPragmaId spec_name sig_ty)
- (mkHsLet spec_binds spec_expr)
- in
+tcTySigs :: [LSig Name] -> TcM [TcSigInfo]
+tcTySigs sigs = mappM tcTySig (filter isVanillaLSig sigs)
- -- Do the rest and combine
- tcSpecSigs sigs `thenM` \ binds_rest ->
- returnM (binds_rest `snocBag` L loc spec_bind)
+tcTySig :: LSig Name -> TcM TcSigInfo
+tcTySig (L span (Sig (L _ name) ty))
+ = setSrcSpan span $
+ do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty
+ ; (tvs, theta, tau) <- tcInstSigType name scoped_names sigma_ty
+ ; loc <- getInstLoc (SigOrigin (SigSkol name))
+ ; return (TcSigInfo { sig_id = mkLocalId name sigma_ty,
+ sig_tvs = tvs, sig_theta = theta, sig_tau = tau,
+ sig_scoped = scoped_names, sig_loc = loc }) }
+ where
+ -- The scoped names are the ones explicitly mentioned
+ -- in the HsForAll. (There may be more in sigma_ty, because
+ -- of nested type synonyms. See Note [Scoped] with TcSigInfo.)
+ scoped_names = case ty of
+ L _ (HsForAllTy Explicit tvs _ _) -> hsLTyVarNames tvs
+ other -> []
-tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs
-tcSpecSigs [] = returnM emptyLHsBinds
+isUnRestrictedGroup :: [LHsBind Name] -> TcSigFun -> TcM Bool
+isUnRestrictedGroup binds sig_fn
+ = do { mono_restriction <- doptM Opt_MonomorphismRestriction
+ ; return (not mono_restriction || all_unrestricted) }
+ where
+ all_unrestricted = all (unrestricted . unLoc) binds
+ has_sig n = isJust (sig_fn n)
+
+ unrestricted (PatBind other _ _ _) = False
+ unrestricted (VarBind v _) = has_sig v
+ unrestricted (FunBind v _ matches _) = unrestricted_match matches
+ || has_sig (unLoc v)
+
+ unrestricted_match (MatchGroup (L _ (Match [] _ _) : _) _) = False
+ -- No args => like a pattern binding
+ unrestricted_match other = True
+ -- Some args => a function binding
\end{code}
+
%************************************************************************
%* *
\subsection[TcBinds-errors]{Error contexts and messages}
= hang (ptext SLIT("In a pattern binding:")) 4 (pprPatBind pat grhss)
-----------------------------------------------
-valSpecSigCtxt v ty
- = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"),
- nest 4 (ppr v <+> dcolon <+> ppr ty)]
-
------------------------------------------------
sigContextsCtxt sig1 sig2
= vcat [ptext SLIT("When matching the contexts of the signatures for"),
nest 2 (vcat [ppr id1 <+> dcolon <+> ppr (idType id1),
= hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed:"))
4 (ppr mbind)
+badUnliftedSig sig
+ = hang (ptext SLIT("Illegal polymorphic signature in an unlifted binding"))
+ 4 (ppr sig)
+
-----------------------------------------------
unboxedTupleErr name ty
= hang (ptext SLIT("Illegal binding of unboxed tuple"))
projects / ghc-hetmet.git / blobdiff