100 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
			
		
		
	
	
			100 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
<section xmlns="http://docbook.org/ns/docbook"
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         xmlns:xlink="http://www.w3.org/1999/xlink"
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         xml:id="sec-language-ocaml">
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 <title>OCaml</title>
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 <para>
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   OCaml libraries should be installed in
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   <literal>$(out)/lib/ocaml/${ocaml.version}/site-lib/</literal>. Such
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   directories are automatically added to the <literal>$OCAMLPATH</literal>
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   environment variable when building another package that depends on them
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   or when opening a <literal>nix-shell</literal>.
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 </para>
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 <para>
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   Given that most of the OCaml ecosystem is now built with dune,
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   nixpkgs includes a convenience build support function called
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   <literal>buildDunePackage</literal> that will build an OCaml package
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   using dune, OCaml and findlib and any additional dependencies provided
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   as <literal>buildInputs</literal> or <literal>propagatedBuildInputs</literal>.
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 </para>
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 <para>
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   Here is a simple package example. It defines an (optional) attribute
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   <literal>minimumOCamlVersion</literal> that will be used to throw a
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   descriptive evaluation error if building with an older OCaml is attempted.
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   It uses the <literal>fetchFromGitHub</literal> fetcher to get its source.
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   It sets the <literal>doCheck</literal> (optional) attribute to
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   <literal>true</literal> which means that tests will be run with
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   <literal>dune runtest -p angstrom</literal> after the build
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   (<literal>dune build -p angstrom</literal>) is complete.
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   It uses <literal>alcotest</literal> as a build input (because it is needed
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   to run the tests) and <literal>bigstringaf</literal> and
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   <literal>result</literal> as propagated build inputs (thus they will also
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   be available to libraries depending on this library).
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   The library will be installed using the <literal>angstrom.install</literal>
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   file that dune generates.
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 </para>
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 <programlisting>
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{ stdenv, fetchFromGitHub, buildDunePackage, alcotest, result, bigstringaf }:
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buildDunePackage rec {
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  pname = "angstrom";
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  version = "0.10.0";
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  minimumOCamlVersion = "4.03";
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  src = fetchFromGitHub {
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    owner  = "inhabitedtype";
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    repo   = pname;
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    rev    = version;
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    sha256 = "0lh6024yf9ds0nh9i93r9m6p5psi8nvrqxl5x7jwl13zb0r9xfpw";
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  };
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  buildInputs = [ alcotest ];
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  propagatedBuildInputs = [ bigstringaf result ];
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  doCheck = true;
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  meta = {
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    homepage = https://github.com/inhabitedtype/angstrom;
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    description = "OCaml parser combinators built for speed and memory efficiency";
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    license = stdenv.lib.licenses.bsd3;
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    maintainers = with stdenv.lib.maintainers; [ sternenseemann ];
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  };
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}
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 </programlisting>
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 <para>
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   Here is a second example, this time using a source archive generated with
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   <literal>dune-release</literal>. It is a good idea to use this archive when
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   it is available as it will usually contain substituted variables such as a
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   <literal>%%VERSION%%</literal> field. This library does not depend
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   on any other OCaml library and no tests are run after building it.
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 </para>
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 <programlisting>
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{ stdenv, fetchurl, buildDunePackage }:
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buildDunePackage rec {
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  pname = "wtf8";
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  version = "1.0.1";
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  minimumOCamlVersion = "4.01";
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  src = fetchurl {
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    url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-${version}.tbz";
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    sha256 = "1msg3vycd3k8qqj61sc23qks541cxpb97vrnrvrhjnqxsqnh6ygq";
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  };
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  meta = with stdenv.lib; {
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    homepage = https://github.com/flowtype/ocaml-wtf8;
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    description = "WTF-8 is a superset of UTF-8 that allows unpaired surrogates.";
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    license = licenses.mit;
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    maintainers = [ maintainers.eqyiel ];
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  };
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}
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 </programlisting>
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</section>
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