#include "HsVersions.h"
-import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun )
-import {-# SOURCE #-} TcExpr ( tcExpr, tcMonoExpr )
+import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun )
+import {-# SOURCE #-} TcExpr ( tcCheckSigma, tcCheckRho )
import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) )
import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..),
- Match(..), HsMatchContext(..), mkMonoBind,
+ Match(..), mkMonoBind,
collectMonoBinders, andMonoBinds,
collectSigTysFromMonoBinds
)
import TcRnMonad
import Inst ( InstOrigin(..), newDicts, newIPDict, instToId )
import TcEnv ( tcExtendLocalValEnv, tcExtendLocalValEnv2, newLocalName )
-import TcUnify ( unifyTauTyLists, checkSigTyVarsWrt, sigCtxt )
+import TcUnify ( Expected(..), newHole, unifyTauTyLists, checkSigTyVarsWrt, sigCtxt )
import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted,
tcSimplifyToDicts, tcSimplifyIPs )
import TcMonoType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..),
)
import TcPat ( tcPat, tcSubPat, tcMonoPatBndr )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcMType ( newTyVar, newTyVarTy, newHoleTyVarTy,
- zonkTcTyVarToTyVar, readHoleResult
- )
+import TcMType ( newTyVar, newTyVarTy, zonkTcTyVarToTyVar )
import TcType ( TcTyVar, mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType,
mkPredTy, mkForAllTy, isUnLiftedType,
unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind
\begin{code}
tcTopBinds :: RenamedHsBinds -> TcM (TcMonoBinds, 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 $
getLclEnv `thenM` \ env ->
= newTyVarTy openTypeKind `thenM` \ ty ->
getSrcLocM `thenM` \ loc ->
newIPDict (IPBind ip) ip ty `thenM` \ (ip', ip_inst) ->
- tcMonoExpr expr ty `thenM` \ expr' ->
+ tcCheckRho expr ty `thenM` \ expr' ->
returnM (ip_inst, (ip', expr'))
tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next
tcBindWithSigs top_lvl bind sigs is_rec `thenM` \ (poly_binds, poly_ids) ->
- getLIE (
- -- Extend the environment to bind the new polymorphic Ids
- tcExtendLocalValEnv poly_ids $
-
- -- Build bindings and IdInfos corresponding to user pragmas
- tcSpecSigs sigs `thenM` \ prag_binds ->
-
- -- Now do whatever happens next, in the augmented envt
- do_next `thenM` \ thing ->
-
- returnM (prag_binds, thing)
- ) `thenM` \ ((prag_binds, thing), lie) ->
-
case top_lvl of
-
- -- 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
- TopLevel
- -> extendLIEs lie `thenM_`
+ 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
+ --
+ -- Subtle (and ugly) point: furthermore at top level we
+ -- return the TcLclEnv, which contains the LIE var; we
+ -- don't want to return the wrong one!
+ -> tc_body poly_ids `thenM` \ (prag_binds, thing) ->
returnM (combiner (mkMonoBind Recursive (poly_binds `andMonoBinds` prag_binds))
thing)
- NotTopLevel
- -> bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds ->
+ NotTopLevel -- For nested bindings we must do teh bindInstsOfLocalFuns thing
+ -> getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) ->
+
-- Create specialisations of functions bound here
+ bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds ->
-- We want to keep non-recursive things non-recursive
-- so that we desugar unlifted bindings correctly
-- aren't guaranteed in dependency order (though we could change
-- that); hence the Recursive marker.
thing)
+ where
+ tc_body poly_ids -- Type check the pragmas and "thing inside"
+ = -- Extend the environment to bind the new polymorphic Ids
+ tcExtendLocalValEnv poly_ids $
+
+ -- Build bindings and IdInfos corresponding to user pragmas
+ tcSpecSigs sigs `thenM` \ prag_binds ->
+
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenM` \ thing ->
+
+ returnM (prag_binds, thing)
\end{code}
) $
-- TYPECHECK THE BINDINGS
- getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', binder_names, mono_ids), lie_req) ->
+ getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', bndr_names_w_ids), lie_req) ->
let
+ (binder_names, mono_ids) = unzip (bagToList bndr_names_w_ids)
tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids
in
\begin{code}
tcMonoBinds :: RenamedMonoBinds
- -> [TcSigInfo]
- -> RecFlag
+ -> [TcSigInfo] -> RecFlag
-> TcM (TcMonoBinds,
- [Name], -- Bound names
- [TcId]) -- Corresponding monomorphic bound things
+ Bag (Name, -- Bound names
+ TcId)) -- Corresponding monomorphic bound things
tcMonoBinds mbinds tc_ty_sigs is_rec
- = tc_mb_pats mbinds `thenM` \ (complete_it, tvs, ids, lie_avail) ->
- let
- id_list = bagToList ids
- (names, mono_ids) = unzip id_list
-
- -- This last defn is the key one:
- -- extend the val envt with bindings for the
- -- things bound in this group, overriding the monomorphic
- -- ids with the polymorphic ones from the pattern
- extra_val_env = case is_rec of
- Recursive -> map mk_bind id_list
- NonRecursive -> []
- in
- -- Don't know how to deal with pattern-bound existentials yet
- checkTc (isEmptyBag tvs && null lie_avail)
- (existentialExplode mbinds) `thenM_`
-
- -- *Before* checking the RHSs, but *after* checking *all* the patterns,
- -- extend the envt with bindings for all the bound ids;
- -- and *then* override with the polymorphic Ids from the signatures
- -- That is the whole point of the "complete_it" stuff.
- --
- -- There's a further wrinkle: we have to delay extending the environment
- -- until after we've dealt with any pattern-bound signature type variables
- -- Consider f (x::a) = ...f...
- -- We're going to check that a isn't unified with anything in the envt,
- -- so f itself had better not be! So we pass the envt binding f into
- -- complete_it, which extends the actual envt in TcMatches.tcMatch, after
- -- dealing with the signature tyvars
-
- complete_it extra_val_env `thenM` \ mbinds' ->
-
- returnM (mbinds', names, mono_ids)
+ -- Three stages:
+ -- 1. Check the patterns, building up an environment binding
+ -- the variables in this group (in the recursive case)
+ -- 2. Extend the environment
+ -- 3. Check the RHSs
+ = tc_mb_pats mbinds `thenM` \ (complete_it, xve) ->
+ tcExtendLocalValEnv2 (bagToList xve) complete_it
where
-
- mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of
- Nothing -> (name, mono_id)
- Just sig -> (idName poly_id, poly_id)
- where
- poly_id = tcSigPolyId sig
-
- tc_mb_pats EmptyMonoBinds
- = returnM (\ xve -> returnM EmptyMonoBinds, emptyBag, emptyBag, [])
+ tc_mb_pats EmptyMonoBinds
+ = returnM (returnM (EmptyMonoBinds, emptyBag), emptyBag)
tc_mb_pats (AndMonoBinds mb1 mb2)
- = tc_mb_pats mb1 `thenM` \ (complete_it1, tvs1, ids1, lie_avail1) ->
- tc_mb_pats mb2 `thenM` \ (complete_it2, tvs2, ids2, lie_avail2) ->
+ = tc_mb_pats mb1 `thenM` \ (complete_it1, xve1) ->
+ tc_mb_pats mb2 `thenM` \ (complete_it2, xve2) ->
let
- complete_it xve = complete_it1 xve `thenM` \ mb1' ->
- complete_it2 xve `thenM` \ mb2' ->
- returnM (AndMonoBinds mb1' mb2')
+ complete_it = complete_it1 `thenM` \ (mb1', bs1) ->
+ complete_it2 `thenM` \ (mb2', bs2) ->
+ returnM (AndMonoBinds mb1' mb2', bs1 `unionBags` bs2)
in
- returnM (complete_it,
- tvs1 `unionBags` tvs2,
- ids1 `unionBags` ids2,
- lie_avail1 ++ lie_avail2)
+ returnM (complete_it, xve1 `unionBags` xve2)
tc_mb_pats (FunMonoBind name inf matches locn)
- = (case maybeSig tc_ty_sigs name of
- Just sig -> returnM (tcSigMonoId sig)
- Nothing -> newLocalName name `thenM` \ bndr_name ->
- newTyVarTy openTypeKind `thenM` \ bndr_ty ->
- -- NB: not a 'hole' tyvar; since there is no type
- -- signature, we revert to ordinary H-M typechecking
- -- which means the variable gets an inferred tau-type
- returnM (mkLocalId bndr_name bndr_ty)
- ) `thenM` \ bndr_id ->
+ -- Three cases:
+ -- a) Type sig supplied
+ -- b) No type sig and recursive
+ -- c) No type sig and non-recursive
+
+ | Just sig <- maybeSig tc_ty_sigs name
+ = let -- (a) There is a type signature
+ -- Use it for the environment extension, and check
+ -- the RHS has the appropriate type (with outer for-alls stripped off)
+ mono_id = tcSigMonoId sig
+ mono_ty = idType mono_id
+ complete_it = addSrcLoc locn $
+ tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
+ in
+ returnM (complete_it, if isRec is_rec then unitBag (name,tcSigPolyId sig)
+ else emptyBag)
+
+ | isRec is_rec
+ = -- (b) No type signature, and recursive
+ -- So we must use an ordinary H-M type variable
+ -- which means the variable gets an inferred tau-type
+ newLocalName name `thenM` \ mono_name ->
+ newTyVarTy openTypeKind `thenM` \ mono_ty ->
let
- bndr_ty = idType bndr_id
- complete_it xve = addSrcLoc locn $
- tcMatchesFun xve name bndr_ty matches `thenM` \ matches' ->
- returnM (FunMonoBind bndr_id inf matches' locn)
+ mono_id = mkLocalId mono_name mono_ty
+ complete_it = addSrcLoc locn $
+ tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
in
- returnM (complete_it, emptyBag, unitBag (name, bndr_id), [])
-
+ returnM (complete_it, unitBag (name, mono_id))
+
+ | otherwise -- (c) No type signature, and non-recursive
+ = let -- So we can use a 'hole' type to infer a higher-rank type
+ complete_it
+ = addSrcLoc locn $
+ newHole `thenM` \ hole ->
+ tcMatchesFun name matches (Infer hole) `thenM` \ matches' ->
+ readMutVar hole `thenM` \ fun_ty ->
+ newLocalName name `thenM` \ mono_name ->
+ let
+ mono_id = mkLocalId mono_name fun_ty
+ in
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
+ in
+ returnM (complete_it, emptyBag)
+
tc_mb_pats bind@(PatMonoBind pat grhss locn)
= addSrcLoc locn $
- newHoleTyVarTy `thenM` \ pat_ty ->
-- Now typecheck the pattern
-- We do now support binding fresh (not-already-in-scope) scoped
-- The type variables are brought into scope in tc_binds_and_then,
-- so we don't have to do anything here.
- tcPat tc_pat_bndr pat pat_ty `thenM` \ (pat', tvs, ids, lie_avail) ->
- readHoleResult pat_ty `thenM` \ pat_ty' ->
+ newHole `thenM` \ hole ->
+ tcPat tc_pat_bndr pat (Infer hole) `thenM` \ (pat', tvs, ids, lie_avail) ->
+ readMutVar hole `thenM` \ pat_ty ->
+
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && null lie_avail)
+ (existentialExplode bind) `thenM_`
+
let
- complete_it xve = addSrcLoc locn $
- addErrCtxt (patMonoBindsCtxt bind) $
- tcExtendLocalValEnv2 xve $
- tcGRHSs PatBindRhs grhss pat_ty' `thenM` \ grhss' ->
- returnM (PatMonoBind pat' grhss' locn)
+ complete_it = addSrcLoc locn $
+ addErrCtxt (patMonoBindsCtxt bind) $
+ tcGRHSsPat grhss (Check pat_ty) `thenM` \ grhss' ->
+ returnM (PatMonoBind pat' grhss' locn, ids)
in
- returnM (complete_it, tvs, ids, lie_avail)
+ returnM (complete_it, if isRec is_rec then ids else emptyBag)
-- tc_pat_bndr is used when dealing with a LHS binder in a pattern.
-- If there was a type sig for that Id, we want to make it much
tc_pat_bndr name pat_ty
= case maybeSig tc_ty_sigs name of
- Nothing
- -> newLocalName name `thenM` \ bndr_name ->
- tcMonoPatBndr bndr_name pat_ty
+ Nothing -> newLocalName name `thenM` \ bndr_name ->
+ tcMonoPatBndr bndr_name pat_ty
Just sig -> addSrcLoc (getSrcLoc name) $
tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn ->
-- Check that f has a more general type, and build a RHS for
-- the spec-pragma-id at the same time
- getLIE (tcExpr (HsVar name) sig_ty) `thenM` \ (spec_expr, spec_lie) ->
+ getLIE (tcCheckSigma (HsVar name) sig_ty) `thenM` \ (spec_expr, spec_lie) ->
-- Squeeze out any Methods (see comments with tcSimplifyToDicts)
tcSimplifyToDicts spec_lie `thenM` \ spec_binds ->
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