homebrew fomula for GHC 7.4.1RC

ghc.rb

require 'formula'

class Ghc < Formula
  homepage 'http://haskell.org/ghc/'
  version '7.4.1RC1'
  if ARGV.include? '--64bit'
    url "http://www.haskell.org/ghc/dist/7.4.1-rc1/ghc-7.4.0.20111219-x86_64-apple-darwin.tar.bz2"
  else
    url "http://www.haskell.org/ghc/dist/7.4.1-rc1/ghc-7.4.0.20111219-i386-apple-darwin.tar.bz2"
  end

  # Avoid stripping the Haskell binaries & libraries.
  # See: http://hackage.haskell.org/trac/ghc/ticket/2458
  skip_clean ['bin', 'lib']

  def options
    [['--64bit', 'Install 64-bit version of GHC (experimental).']]
  end

  def install
    if ARGV.build_devel?
      opoo "The current version of haskell-platform will NOT work with this version of GHC!"
    end
    if ARGV.include? '--64bit'
      if Hardware.is_64_bit?
        opoo "The x86_64 version is experimental!"
      else
        onoe "The x86_64 version is only for 64-bit hardware."
        exit 1
      end
    end

    system "./configure --prefix=#{prefix}"
    system "make install"
  end

  def caveats; <<-EOS.undent
    The 32-bit version of GHC is installed by default, as the x84_64 version is
    labelled experimental. Override with `--64bit`.

    This brew is for GHC only; you might also be interested in haskell-platform.
    EOS
  end
end