import {-# SOURCE #-} TcUnify( unifyTauTy )
import TcEnv -- temp
-import HsSyn ( HsBind(..), LHsBinds, HsExpr(..), LHsExpr, pprLHsBinds )
+import HsSyn ( HsBind(..), HsExpr(..), LHsExpr, emptyLHsBinds )
import TcHsSyn ( TcId, TcDictBinds, mkHsApp, mkHsTyApp, mkHsDictApp )
import TcRnMonad
import TcEnv ( tcGetGlobalTyVars, tcLookupId, findGlobals )
import InstEnv ( lookupInstEnv, classInstances )
import TcMType ( zonkTcTyVarsAndFV, tcInstTyVars, checkAmbiguity )
-import TcType ( TcTyVar, TcTyVarSet, ThetaType, TyVarDetails(VanillaTv),
- mkClassPred, isOverloadedTy, mkTyConApp,
+import TcType ( TcTyVar, TcTyVarSet, ThetaType,
+ mkClassPred, isOverloadedTy, mkTyConApp,
mkTyVarTy, tcGetTyVar, isTyVarClassPred, mkTyVarTys,
tyVarsOfPred, tcEqType, pprPred )
import Id ( idType, mkUserLocal )
import PrelInfo ( isNumericClass )
import PrelNames ( splitName, fstName, sndName, integerTyConName,
showClassKey, eqClassKey, ordClassKey )
-import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import Type ( zipTopTvSubst, substTheta, substTy )
import TysWiredIn ( pairTyCon, doubleTy )
import ErrUtils ( Message )
import VarSet
| isClassDict inst = DontReduceUnlessConstant -- Dicts
| otherwise = ReduceMe -- Lits and Methods
in
- traceTc (text "infloop" <+> vcat [ppr tau_tvs', ppr wanteds', ppr preds, ppr (grow preds tau_tvs'), ppr qtvs]) `thenM_`
+ traceTc (text "infloop" <+> vcat [ppr tau_tvs', ppr wanteds', ppr preds,
+ ppr (grow preds tau_tvs'), ppr qtvs]) `thenM_`
-- Step 2
reduceContext doc try_me [] wanteds' `thenM` \ (no_improvement, frees, binds, irreds) ->
givens wanted_lie `thenM` \ (qtvs', binds) ->
returnM binds
where
- get_qtvs = zonkTcTyVarsAndFV qtvs
+-- get_qtvs = zonkTcTyVarsAndFV qtvs
+ get_qtvs = return (mkVarSet qtvs)
-- tcSimplifyInferCheck is used when we know the constraints we are to simplify
@LIE@), as well as the @HsBinds@ generated.
\begin{code}
-bindInstsOfLocalFuns :: [Inst] -> [TcId] -> TcM (LHsBinds TcId)
+bindInstsOfLocalFuns :: [Inst] -> [TcId] -> TcM TcDictBinds
+-- Simlifies only MethodInsts, and generate only bindings of form
+-- fm = f tys dicts
+-- We're careful not to even generate bindings of the form
+-- d1 = d2
+-- You'd think that'd be fine, but it interacts with what is
+-- arguably a bug in Match.tidyEqnInfo (see notes there)
bindInstsOfLocalFuns wanteds local_ids
| null overloaded_ids
-- Common case
= extendLIEs wanteds `thenM_`
- returnM emptyBag
+ returnM emptyLHsBinds
| otherwise
- = simpleReduceLoop doc try_me wanteds `thenM` \ (frees, binds, irreds) ->
+ = simpleReduceLoop doc try_me for_me `thenM` \ (frees, binds, irreds) ->
ASSERT( null irreds )
+ extendLIEs not_for_me `thenM_`
extendLIEs frees `thenM_`
returnM binds
where
doc = text "bindInsts" <+> ppr local_ids
overloaded_ids = filter is_overloaded local_ids
is_overloaded id = isOverloadedTy (idType id)
+ (for_me, not_for_me) = partition (isMethodFor overloaded_set) wanteds
overloaded_set = mkVarSet overloaded_ids -- There can occasionally be a lot of them
-- so it's worth building a set, so that
-- lookup (in isMethodFor) is faster
-
- try_me inst | isMethodFor overloaded_set inst = ReduceMe
- | otherwise = Free
+ try_me inst | isMethod inst = ReduceMe
+ | otherwise = Free
\end{code}
returnM False
where
unify ((qtvs, pairs), doc)
- = addErrCtxt doc $
- tcInstTyVars VanillaTv (varSetElems qtvs) `thenM` \ (_, _, tenv) ->
+ = addErrCtxt doc $
+ tcInstTyVars (varSetElems qtvs) `thenM` \ (_, _, tenv) ->
mapM_ (unif_pr tenv) pairs
unif_pr tenv (ty1,ty2) = unifyTauTy (substTy tenv ty1) (substTy tenv ty2)
\end{code}
where
(clas, tys) = getDictClassTys dict
(tyvars, sc_theta, sc_sels, _) = classBigSig clas
- sc_theta' = substTheta (mkTopTyVarSubst tyvars tys) sc_theta
+ sc_theta' = substTheta (zipTopTvSubst tyvars tys) sc_theta
add_sc avails (sc_dict, sc_sel) -- Add it, and its superclasses
| add_me sc_dict = addSCs is_loop avails' sc_dict
-> TcM ThetaType -- Needed
tcSimplifyDeriv tyvars theta
- = tcInstTyVars VanillaTv tyvars `thenM` \ (tvs, _, tenv) ->
+ = tcInstTyVars tyvars `thenM` \ (tvs, _, tenv) ->
-- The main loop may do unification, and that may crash if
-- it doesn't see a TcTyVar, so we have to instantiate. Sigh
-- ToDo: what if two of them do get unified?
- newDicts DataDeclOrigin (substTheta tenv theta) `thenM` \ wanteds ->
+ newDicts DerivOrigin (substTheta tenv theta) `thenM` \ wanteds ->
simpleReduceLoop doc reduceMe wanteds `thenM` \ (frees, _, irreds) ->
ASSERT( null frees ) -- reduceMe never returns Free
-- of problems; in particular, it's hard to compare solutions for
-- equality when finding the fixpoint. So I just rule it out for now.
- rev_env = mkTopTyVarSubst tvs (mkTyVarTys tyvars)
+ rev_env = zipTopTvSubst tvs (mkTyVarTys tyvars)
-- This reverse-mapping is a Royal Pain,
-- but the result should mention TyVars not TcTyVars
in
-> TcM ()
tcSimplifyDefault theta
- = newDicts DataDeclOrigin theta `thenM` \ wanteds ->
+ = newDicts DefaultOrigin theta `thenM` \ wanteds ->
simpleReduceLoop doc reduceMe wanteds `thenM` \ (frees, _, irreds) ->
ASSERT( null frees ) -- try_me never returns Free
addNoInstanceErrs Nothing [] irreds `thenM_`
report :: [(Inst,[TcTyVar])] -> TcM ()
report pairs@((inst,tvs) : _) -- The pairs share a common set of ambiguous tyvars
= mkMonomorphismMsg tidy_env dicts `thenM` \ (tidy_env, mono_msg) ->
- addSrcSpan (instLocSrcSpan (instLoc inst)) $
+ setSrcSpan (instLocSrcSpan (instLoc inst)) $
-- the location of the first one will do for the err message
addErrTcM (tidy_env, msg $$ mono_msg)
where
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