Re: api to access .hi files

2 Aug 2019

      Brandon Allbery  writes:
...
No, those are in base. But I don't think you would be seeing imported names
as such there, come to think of it, only names declared locally.
Hmm, then perhaps I misunderstand what it's doing.

If I do what I thought might be the equivalent ghci command

    λ> :l exe/Main.hs
    [1 of 1] Compiling Main             ( exe/Main.hs, interpreted )
    Ok, one module loaded.
    λ> :browse
    main :: IO ()

we see one symbol. So this is already different to what my application
is doing.

But the information I want is when we do something like

    λ> :browse! *Main
    ... everything in scope including Prelude and GHC ...

An option I have considered would be to manually parse the import
sections and then perform the Module lookup via the pkg database, but
that approach has many flaws because it means reimplementing a lot of
the early compilation stages manually and I'm sure dealing with explicit
import lists (and hiding, not to mention dealing with lang extensions
such as TypeOperators) is probably quite tricky to get right.
...
On Fri, Aug 2, 2019 at 4:06 PM Sam Halliday  wrote:
...
Brandon Allbery  writes:
...
At a guess, because the ghc package defaults to being hidden (it's
creating
a new ghc instance at runtime, so the visibility of the ghc package when
compiling your code is not relevant) you need to do the ghc-api
equivalent
of "-package ghc". Or for testing just "ghc-pkg expose ghc".
Hmm, would that also explain why the Prelude and Control.Monad modules
are not shown either?
Is there a way to expose all modules programmatically?
...
On Fri, Aug 2, 2019 at 3:47 PM Sam Halliday 
wrote:
...
...
To answer my own question with a solution and another question:
Sam Halliday writes:
...
I'm mostly interested in gathering information about symbols and their
type signatures. As a first exercise: given a module+import section
for a haskell source file, I want to find out which symbols (and their
types) are available. Like :browse in ghci, but programmatically.
This is answered by Stephen Diehl's blog post on the ghc api! How lucky
I am: http://www.stephendiehl.com/posts/ghc_01.html
He points to getNamesInScope
Unfortunately I'm getting zero Names back when loading a file that
imports several modules from ghc. Is there something I'm missing in the
following?
module Main where
import           Control.Monad
import           Control.Monad.IO.Class
import           GHC
import           GHC.Paths              (libdir)
main = runGhc (Just libdir) $ do
  dflags <- getSessionDynFlags
  void $ setSessionDynFlags $ dflags {
      hscTarget = HscInterpreted
    , ghcLink   = LinkInMemory
    }
  addTarget $ Target (TargetFile "exe/Main.hs" Nothing) False Nothing
  res <- load LoadAllTargets
  liftIO $ putStrLn $ showPpr dflags res
  names <- getNamesInScope
  liftIO $ putStrLn $ "seen " <> (show $ length names) <> " Names"
--
Best regards,
Sam
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--
brandon s allbery kf8nh
allbery.b@gmail.com
--
Best regards,
Sam
-- 
brandon s allbery kf8nh
allbery.b@gmail.com
-- 
Best regards,
Sam