Top-level type signatures in TcGblEnv?

Edsko de Vries edskodevries at
Mon Feb 18 15:02:55 CET 2013

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

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


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