Re: [Haskell-cafe] Cabal, xmonad-contrib, X11-xft, pkg-config ... questioning my sanity

On Mon, Dec 6, 2010 at 7:15 AM, Duncan Coutts wrote:

On 6 December 2010 11:02, Jacek Generowicz wrote:

...

It a appears that a program which does not exist on my computer seems to insist on a package version which does not exist in my universe, I'm starting to wonder whether I have lost my marbles. Could some kind soul please point me in some sensible direction?

cabal install xmonad-contrib Resolving dependencies... Configuring X11-xft-0.3... cabal: pkg-config version >=0.9.0 is required but it could not be found.

...

X11-xft version 0.9.0 doesn't even exist, as far a I can tell

In the development version of cabal we have changed that error message to try and make it clear that it is looking for a program called pkg-config, not a Haskell package or a C lib.

cabal: The program pkg-config version >=0.9.0 is required but it could not be found.

Do you think that message would have helped avoid your confusion? Is there an alternative message that would have been better?

pkg-config [1] is a tool used by C libraries to describe things like dependencies on other C libs and what C compiler flags are needed to use the packages.

The Haskell package X11-xft is a binding to the C library xft. On most modern unix systems xft C library provides meta-data that pkg-config can use. For example, on my system I can run:

$ pkg-config --cflags xft -I/usr/include/freetype2

$ pkg-config --libs xft -lXft -lXrender -lfontconfig -lfreetype -lX11

Cabal does exactly the same thing, to work out what flags are needed to use the xft C library.

The problem on your system is that the pkg-config program is not installed. Perhaps on OSX it comes with Xcode, I'm not sure. It may well also be the case that you don't have the development files for X11 or xft installed either (e.g. C header files). Hopefully some OSX person can advise you on what you need to install to do X11 development on OSX.

On my Mac 'which -a pkg-config' returns: /opt/local/bin/pkg-config /opt/local/bin/pkg-config I'm not sure why it prints twice. The folder means I've installed it from MacPorts, which also means I guess you'll need to install the MacPorts version of X11-xft, but I'm not sure. However building Haskell libraries against MacPorts often leads to nightmarish scenarios involving libiconv, but I haven't run into that on my current installation yet. Antoine

[1]: http://pkg-config.freedesktop.org/wiki/

Duncan

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