nixpkgs/pkgs/applications/editors/yi/yi-custom.nix

# This is a manually-written expression over an in-tree cabal file.
# It's awkward but this way allows the package user to pass in
# extraPackages without much extra hassle on their end, similarly how
# the XMonad service handles it: the difference is that we don't have
# anything like XMONAD_GHC…
#
# The idea is that the user changes their configs using any libraries
# he likes and then builds it using this expression. Once that's done,
# ‘reload’ and similar functions should all work as long as the user
# doesn't need new libraries at which point they should add them to
# extraPackages and rebuild from the expression.
{ cabal, yi, extraPackages, makeWrapper, ghcWithPackages }:
let
  w = ghcWithPackages (self: [ yi ] ++ extraPackages self);
  wrappedGhc = w.override { ignoreCollisions = true; };
in
cabal.mkDerivation (self: rec {
  pname = "yi-custom";
  version = "0.0.0.1";
  src = ./yi-custom-cabal;
  isLibrary = true;
  buildDepends = [ yi ];
  buildTools = [ makeWrapper ];
  noHaddock = true;
  doCheck = false;

  postInstall = ''
    makeWrapper ${yi}/bin/yi $out/bin/yi \
      --set NIX_GHC ${wrappedGhc}/bin/ghc \
      --set NIX_GHC_LIBDIR ${wrappedGhc}/lib/ghc-${self.ghc.version}
  '';
  meta = {
    homepage = "http://haskell.org/haskellwiki/Yi";
    description = "Wrapper over user-specified Haskell libraries for use in Yi config";
    license = self.stdenv.lib.licenses.publicDomain;
    platforms = self.ghc.meta.platforms;
    maintainers = with self.stdenv.lib.maintainers; [ fuuzetsu ];
  };

})