# Coq

Coq libraries should be installed in `$(out)/lib/coq/${coq.coq-version}/user-contrib/`. Such directories are automatically added to the `$COQPATH` environment variable by the hook defined in the Coq derivation.

Some libraries require OCaml and sometimes also Camlp5. The exact versions that were used to build Coq are saved in the `coq.ocaml` and `coq.camlp5` attributes.

Here is a simple package example. It is a pure Coq library, thus it only depends on Coq. Its `makefile` has been generated using `coq_makefile` so we only have to set the `$COQLIB` variable at install time.

    {stdenv, fetchurl, coq}:
    stdenv.mkDerivation {
      src = fetchurl {
        url = http://coq.inria.fr/pylons/contribs/files/Karatsuba/v8.4/Karatsuba.tar.gz;
        sha256 = "0ymfpv4v49k4fm63nq6gcl1hbnnxrvjjp7yzc4973n49b853c5b1";
      };

      name = "coq-karatsuba";

      buildInputs = [ coq ];

      installFlags = "COQLIB=$(out)/lib/coq/${coq.coq-version}/";
    }