[Gtk2hs-devel] Print understandable information when user don't install gtk2hs-buildtools

[Andy S. <laz...@gm...>]

Hi Axel,

Have many people at #haskell ask me why 'gtk' package can't install
successful.
At last, i found they're not install gtk2hs-buildtools.

Most people won't read gtk2hs manual, just do "cabal install gtk" and
expect everything fine, and *many* people just think below error is
fault of 'gtk' and give up to install:

------------------------------> error start <------------------------------
Resolving dependencies...
Configuring gtk-0.11.2...
setup: gtk2hsC2hs is required but it could not be found.
setup: ./gtk.cabal has been changed, please re-configure.
Resolving dependencies...
Configuring gtk-0.11.2...
setup: gtk2hsC2hs is required but it could not be found.
cabal: Error: some packages failed to install:
gtk-0.11.2 failed during the configure step. The exception was:
ExitFailure 1
------------------------------> error end   <------------------------------

Currently, is two ways fix this problem:

1) Buid dummy module let 'gtk' depend, perhaps you don't like this ugly
way. :)

2) We search gtk2hsC2hs in PATH, if not found, print below information:
"Please install package 'gtk2hs-buildtools' first or make sure $HOME/.cabal in your PATH".

Then user at least know he need install gtk2hs-buildtools first.

What do you think?

  -- Andy