CHICKEN is a R⁵RS-compliant Scheme compiler. It includes an interactive mode and a custom package format, "eggs".
Eggs described in nixpkgs are available inside the
chickenPackages.chickenEggs attrset. Including an egg as a build input is
done in the typical Nix fashion. For example, to include support for SRFI
189 in a derivation, one
buildInputs = [ chicken chickenPackages.chickenEggs.srfi-189 ];
chicken and its eggs have a setup hook which configures the environment
nixpkgs only knows about a subset of all published eggs. It uses egg2nix to generate a package set from a list of eggs to include.
The package set is regenerated by running the following shell commands:
$ nix-shell -p chickenPackages.egg2nix $ cd pkgs/development/compilers/chicken/5/ $ egg2nix eggs.scm > eggs.nix
When we run
egg2nix, we obtain one collection of eggs with
mutually-compatible versions. This means that when we add new eggs, we may
need to update existing eggs. To keep those separate, follow the procedure for
updating eggs before including more eggs.
To include more eggs, edit
The first section of this file lists eggs which are required by
itself; all other eggs go into the second section. After editing, follow the
procedure for updating eggs.