Refresh the Ocaml package examples; document useDune2 (#127520)

The current example in the manual no longer builds, mainly because
`useDune2 = true` is required, but also because the inputs have changed.
The new examples are copied verbatim from nixpkgs.
This commit is contained in:
Graham Fawcett 2021-06-22 12:53:27 -04:00 committed by GitHub
parent b4b3372763
commit d26902aef9
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23

View file

@ -4,60 +4,83 @@ OCaml libraries should be installed in `$(out)/lib/ocaml/${ocaml.version}/site-l
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.
Here is a simple package example.
- It defines an (optional) attribute `minimalOCamlVersion` 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.
- `useDune2 = true` ensures that the latest version of Dune is used for the
build (this may become the default value in a future release).
- It sets the optional `doCheck` attribute such that tests will be run with
`dune runtest -p angstrom` after the build (`dune build -p angstrom`) is
complete, but only if the Ocaml version is at at least `"4.05"`.
- It uses the package `ocaml-syntax-shims` as a build input, `alcotest` and
`ppx_let` as check inputs (because they are 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.
```nix
{ lib
, fetchFromGitHub
, buildDunePackage
, alcotest
, result
, bigstringaf
}:
{ lib,
fetchFromGitHub,
buildDunePackage,
ocaml,
ocaml-syntax-shims,
alcotest,
result,
bigstringaf,
ppx_let }:
buildDunePackage rec {
pname = "angstrom";
version = "0.10.0";
version = "0.15.0";
useDune2 = true;
minimumOCamlVersion = "4.03";
minimalOCamlVersion = "4.04";
src = fetchFromGitHub {
owner = "inhabitedtype";
repo = pname;
rev = version;
sha256 = "0lh6024yf9ds0nh9i93r9m6p5psi8nvrqxl5x7jwl13zb0r9xfpw";
sha256 = "1hmrkdcdlkwy7rxhngf3cv3sa61cznnd9p5lmqhx20664gx2ibrh";
};
buildInputs = [ alcotest ];
checkInputs = [ alcotest ppx_let ];
buildInputs = [ ocaml-syntax-shims ];
propagatedBuildInputs = [ bigstringaf result ];
doCheck = true;
doCheck = lib.versionAtLeast ocaml.version "4.05";
meta = with lib; {
meta = {
homepage = "https://github.com/inhabitedtype/angstrom";
description = "OCaml parser combinators built for speed and memory efficiency";
license = licenses.bsd3;
maintainers = with maintainers; [ sternenseemann ];
license = lib.licenses.bsd3;
maintainers = with 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.
```nix
{ lib
, fetchurl
, buildDunePackage
}:
{ lib, fetchurl, buildDunePackage }:
buildDunePackage rec {
pname = "wtf8";
version = "1.0.1";
version = "1.0.2";
minimumOCamlVersion = "4.01";
useDune2 = true;
minimalOCamlVersion = "4.02";
src = fetchurl {
url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-${version}.tbz";
sha256 = "1msg3vycd3k8qqj61sc23qks541cxpb97vrnrvrhjnqxsqnh6ygq";
url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-v${version}.tbz";
sha256 = "09ygcxxd5warkdzz17rgpidrd0pg14cy2svvnvy1hna080lzg7vp";
};
meta = with lib; {