Hs-pkg-config

Description

Library for creating pkg-config configuration files from Haskell. Pkg-config is a tool for inserting correct compiler options when compiling libraries or applications. It is language-agnostic, but mainly used for building various C or C++ libraries and applications.

One of the possible usage examples of this library is generating .pc files from Shake build system.

Example

Following Haskell code is able to generate package configuration file named foo.pc for library foo:

{-# LANGUAGE OverloadedStrings #-}
module Main (main)
  where

import Data.String (IsString)

import Data.Default.Class (Default(def))
   -- From data-default-class library:
   -- http://hackage.haskell.org/package/data-default-class

import Control.Lens
   -- From lens library:
   -- http://hackage.haskell.org/package/lens

import Data.PkgConfig


libraryBaseName :: IsString a => a
libraryBaseName = "foo"

main :: IO ()
main = writePkgConfig (libraryBaseName ++ ".pc") libPkgConfig
  where
    libPkgConfig = def
        & pkgVariables   .~
            [ ("prefix",     "/usr/local"              )
            , ("includedir", var "prefix" </> "include")
            , ("libdir",     var "prefix" </> "lib"    )
            , ("arch",       "i386"                    )
            ]
        & pkgName        .~ libraryBaseName
        & pkgDescription .~ "Example pkg-config."
        & pkgVersion     .~ version [1, 2, 3]
        & pkgCflags      .~ includes [var "includedir"]
        & pkgRequires    .~ list
            [ "bar" ~> [0], "bar" ~<= [3, 1]
            , "baz" ~= [1, 2, 3]
            ]
        & pkgLibs        .~ options
            [ libraryPath [var "libdir", var "libdir" </> var "arch"]
            , libraries [libraryBaseName]
            ]

Content of foo.pc:

prefix=/usr/local
includedir=${prefix}/include
libdir=${prefix}/lib
arch=i386

Name: foo
Description: Example pkg-config.
Version: 1.2.3
Requires: bar > 0, bar <= 3.1, baz = 1.2.3
Cflags: -I"${includedir}"
Libs: -L"${libdir}" -L"${libdir}/${arch}" -lfoo

Now lets see if pkg-config would be able to tell us something about this library:

$ PKG_CONFIG_PATH=`pwd` pkg-config --modversion foo
1.2.3

Note that asking for --cflags or other options would result in error saying that it is unable to find bar and baz libraries. That is OK, it means that it is able to parse file correctly, we just hadn't provided bar.pc and baz.pc. If we delete lines that define Requires: field, then pkg-config would be able to give us --cflags, --libs, etc. You can try it.

Building options

• -fpedantic (disabled by default)

  Pass additional warning flags including -Werror to GHC during compilation.