"info" command requires both "main" and "module" specified

[edkolev]

Hi, and thanks for this project!

I noticed the "info" command cannot be executed without both "main" and "module" specified.

To reproduce:

1. Add file c.hs

   f = 'c'

2. run hdevtools info

   hdevtools admin --stop-server
   hdevtools admin --start-server
   hdevtools info c.hs f

3. get error, instead of the correct type f :: Char

   hs:1:1:
       The IO action ‘main’ is not defined in module ‘Main’
   Error loading targets
   

BTW GHCi can guess the type of f:

echo ":type f" | ghci c.hs
GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( c.hs, interpreted )
Ok, modules loaded: Main.
ghci> f :: Char

To get the type of f, both "main" and "module" need to be defined:

1. add file a.hs

   module Main where
   
   main = undefined
   
   f = 'a'

2. run info (same commands as in 2. above)

3. get correct output

   f :: Char       -- Defined at /private/tmp/a.hs:5:1
   

I haven't checked if the type command has this same issue.

This version of hdevtools is:

hdevtools --version
hdevtools: version 0.1.3.1 (ghc-7.10.3-x86_64-darwin, cabal-1.22.5.0)

[ch1bo]

Hey thanks for reporting this.

Seems to me that the ghci program just adds a main function and handles the module-less .hs file in a hypothetical Main module before loading it using the GHC API.

Anyone interested in implementing this? ;)

[edkolev]

Hi

I'm willing to try fixing this. Could you share some basic tips on hacking on hdevtools? GHC's API seems a bit cryptic, and that's the part of the code that I'm having difficulties with.

For example, is there a way to run getIdentifierInfo in ghci? I tried calling it in the runGhc monad but I got an error (sorry I can't paste the error right now; it was something like "panic, the impossible happened").

[ch1bo]

Hm, not much of a help there as I just fixed stuff here and there. Far from real development on this project.

In order to run the ghc monad properly you might have to set up the package databases, flags etc similar to configSession.

In the end I usually debugged code using prints and traces (module Debug.Trace) and ran the scenario manually.