OCaml
OCaml libraries should be installed in
$(out)/lib/ocaml/${ocaml.version}/site-lib/. Such
directories are automatically added to the $OCAMLPATH
environment variable when building another package that depends on them or
when opening a nix-shell.
Given that most of the OCaml ecosystem is now built with dune, nixpkgs
includes a convenience build support function called
buildDunePackage that will build an OCaml package using
dune, OCaml and findlib and any additional dependencies provided as
buildInputs or propagatedBuildInputs.
Here is a simple package example. It defines an (optional) attribute
minimumOCamlVersion that will be used to throw a
descriptive evaluation error if building with an older OCaml is attempted. It
uses the fetchFromGitHub fetcher to get its source. It
sets the doCheck (optional) attribute to
true which means that tests will be run with dune
runtest -p angstrom after the build (dune build -p
angstrom) is complete. It uses alcotest as a
build input (because it is needed to run the tests) and
bigstringaf and result as propagated
build inputs (thus they will also be available to libraries depending on this
library). The library will be installed using the
angstrom.install file that dune generates.
{ stdenv, fetchFromGitHub, buildDunePackage, alcotest, result, bigstringaf }:
buildDunePackage rec {
pname = "angstrom";
version = "0.10.0";
minimumOCamlVersion = "4.03";
src = fetchFromGitHub {
owner = "inhabitedtype";
repo = pname;
rev = version;
sha256 = "0lh6024yf9ds0nh9i93r9m6p5psi8nvrqxl5x7jwl13zb0r9xfpw";
};
buildInputs = [ alcotest ];
propagatedBuildInputs = [ bigstringaf result ];
doCheck = true;
meta = {
homepage = https://github.com/inhabitedtype/angstrom;
description = "OCaml parser combinators built for speed and memory efficiency";
license = stdenv.lib.licenses.bsd3;
maintainers = with stdenv.lib.maintainers; [ sternenseemann ];
};
}
Here is a second example, this time using a source archive generated with
dune-release. It is a good idea to use this archive when
it is available as it will usually contain substituted variables such as a
%%VERSION%% field. This library does not depend on any
other OCaml library and no tests are run after building it.
{ stdenv, fetchurl, buildDunePackage }:
buildDunePackage rec {
pname = "wtf8";
version = "1.0.1";
minimumOCamlVersion = "4.01";
src = fetchurl {
url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-${version}.tbz";
sha256 = "1msg3vycd3k8qqj61sc23qks541cxpb97vrnrvrhjnqxsqnh6ygq";
};
meta = with stdenv.lib; {
homepage = https://github.com/flowtype/ocaml-wtf8;
description = "WTF-8 is a superset of UTF-8 that allows unpaired surrogates.";
license = licenses.mit;
maintainers = [ maintainers.eqyiel ];
};
}