Top-level type signatures in TcGblEnv?

Simon Peyton-Jones simonpj at
Mon Feb 25 17:41:34 CET 2013

The SrcSpan of the binding site is stored inside the Id.  getSrcSpan should do it.


From: Edsko de Vries [mailto:edskodevries at]
Sent: 25 February 2013 16:27
To: Simon Peyton-Jones
Cc: ghc-devs at
Subject: Re: Top-level type signatures in TcGblEnv?

I'm sorry, I don't see any location information ("Located .." types) in tcg_type_env?


On Mon, Feb 25, 2013 at 3:22 PM, Simon Peyton-Jones <simonpj at<mailto:simonpj at>> wrote:
Can't you just use the range of the tcg_type_env?


From: Edsko de Vries [mailto:edskodevries at<mailto:edskodevries at>]
Sent: 18 February 2013 14:03
To: Simon Peyton-Jones
Cc: ghc-devs at<mailto:ghc-devs at>
Subject: Top-level type signatures in TcGblEnv?

Dear Simon, other ghc devs,

I hooked into genericHscRecompile to traverse the typechecked source and construct an environment of type

     [(SrcSpan, Id)]

recording all identifiers in the source with their type, definition site, etc. To be precise, I am traversing the

    tcg_binds     :: LHsBinds Id,           -- Value bindings in this module

field of the TcGblEnv structure returned by the type checker. The problem is that I have so far been unable to find top-level user-supplied type annotations inside LHsBinds. The closest thing I've found is the PostTcType of a MatchGroup, but that is not Located; what I'm really looking for is an LSig.

Now, let-bindings get a HsValBindsLR instead of an LHsBinds, and that *does* contain signatures. My question is two-fold:

1. First, am I missing something? Are there LSigs somewhere inside the TcGblEnv where I simply haven't seen them?

2. If not, is there a good reason why tcg_binds is an LHsBinds rather than an HsValBindsLR? And if there isn't, would you accept a patch making the change?



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