Well, my tcLocalBinds seems to have a different type then yours (this is from my copy of 7.6.3 and it's the same in the HEAD that I just synced): tcLocalBinds :: HsLocalBinds Name -> TcM thing -> TcM (HsLocalBinds TcId, thing) If I want to get a GblEnv out, I can use getGblEnv, but doing this: mkId :: Maybe FreeVars -> LHsExpr Name -> Name -> TcM Id mkId fvs expr@(L l _) nm = do ((binds', gbl_env),lie) <- captureConstraints $ tcLocalBinds binds getGblEnv setGblEnv gbl_env (tcLookupId nm) where binds = HsValBinds $ ValBindsOut [(NonRecursive, unitBag fixbnd)] [] the_bind = mkTopFunBind (L l nm) [mkMatch [] expr emptyLocalBinds] fixbnd = L l $ maybe the_bind (\vs -> the_bind { bind_fvs = vs }) fvs fails on the tcLookupId with a GHC internal error complaining that my name is "not in scope during type checking, but it passed the renamer." Ph. From: Simon Peyton-Jones [mailto:simonpj@microsoft.com] Sent: dinsdag 10 september 2013 14:19 To: Holzenspies, P.K.F. (EWI) Cc: glasgow-haskell-users@haskell.org Subject: RE: Question about correct GHC-API use for type checking (or zonking, or tidying) What goes wrong if you follow my suggestion below? tcLocalBinds takes a set of bindings, such as x=e and returns a GblEnv whose type envt is extended with a binding for x with its generalised type. This type wil indeed be closed, unless the current environment (in which tcLocalBinds runs) has bindings with open types. Which in your case it probably doesn't. I feel that I am not being helpful but I'm not sure how to help more. S From: "Philip K.F. Hölzenspies" [mailto:p.k.f.holzenspies@utwente.nl] Sent: 04 September 2013 21:25 To: Simon Peyton-Jones Cc: glasgow-haskell-users@haskell.orgmailto:glasgow-haskell-users@haskell.org Subject: Re: Question about correct GHC-API use for type checking (or zonking, or tidying) Ah, this is good to know. What I really would like is a function: mkId :: Name -> LHsExpr Name -> TcM Id where that Id is something I can store in my own monad (IA). The meaning of this, is indeed "let <name> = <expression>" as a top-level binding. The behaviour should actually be the same as that statement at the ghci-prompt. My IA monad implements liftTcM as something that invokes a TcM-monad, i.e. liftTcM :: TcM b -> IA b liftTcM thing_inside = do hsc_env <- getSession stored_ids <- getStoredIds :: IA [Id] -- this is the list of all Ids made through mkId mentioned above ioMsgMaybe . initTcPrintErrors hsc_env iNTERACTIVE $ setInteractiveContext hsc_env (hsc_IC hsc_env) $ tcExtendGlobalValEnv stored_ids $ -- or tcExtendIdEnv?? thing_inside In the example you give below, I'm curious which "thing_inside" you give to tcLocalBinds to get you the correct global environment. Also, if I do what you suggest, i.e. poly_id <- setGblEnv gbl_env (tcLookupId the_id_name) is that poly_id "self contained," in the sense that I can put it in a new instantiation as shown above? Regards, Philip [cid:image001.jpg@01CEAEDB.407DA510] Simon Peyton-Jonesmailto:simonpj@microsoft.com September 4, 2013 6:00 PM The id you are getting is a monomorphic id, with a type like a->a, not the polymorphic forall a. a->a. You don't want to go round arbitrarily creating a new Id with the same unique but a different type. I have no idea what would happen then. It's hard for me to understand just what you code is trying to do. I think you are making bindig it = <some expr> and then you want the type of "it". Maybe something like (binds', gbl_env) <- tcLocalBinds (..your bindin..) poly_id <- setGblEnv gbl_env (tcLooupId the_id_name) But I'm not totally sure. S