OCaml: Difference between revisions

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~~Most packages related to~~ OCaml~~, in particular the~~ OCaml ~~compiler and many libraries, belong to the '''ocamlPackages''' attribute set~~ of ~~nixpkgs~~.

[[File:OCaml Logo.svg|alt=The OCaml logo: an orange background with a white foreground of a camel.|thumb|OCaml logo]]

~~== Findlib, ocamlfind ==~~

According to the official [ocaml.org Ocaml website]:<blockquote>

[Ocaml is]... an industrial-strength functional programming language with an emphasis on expressiveness and safety </blockquote>

== Developping in OCaml with Nix ==

Most packages related to OCaml, in particular the OCaml compiler and many libraries, belong to the '''ocamlPackages''' attribute set of nixpkgs. Tools for OCaml development are, in particular, available:

* the [https://dune.build/ dune] builder;

* the [https://github.com/ocaml/ocaml-lsp OCaml language server];

* the [https://github.com/ocaml-ppx/ocamlformat ocamlformat formatter].

=== Build tooling ===

Modern development practices in OCaml tend to use '''dune''', a builder dedicated for OCaml projects. Nixpkgs provide a dedicated builder: [https://nixos.org/manual/nixpkgs/stable/#sec-language-ocaml-packaging buildDuneProject].

'''dune''' can generate a '''.opam''' file, which can be ingested by tools like [https://github.com/tweag/opam-nix opam-nix] to automatically generate a derivation.

Manual package building is also possible using the following approaches:

==== Findlib, ocamlfind ====

OCaml libraries are usually located using [http://projects.camlcity.org/projects/findlib.html findlib] and the associated '''ocamlfind''' tool. These tools are found under the '''ocamlPackages.findlib''' attribute and rely on the '''OCAMLPATH''' environment variable.

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This hook also sets the '''CAML_LD_LIBRARY_PATH''' environment variable that is used for locating the dynamically loaded shared libraries (aka stublibs).

== Scripting with OCaml ==

=== Scripting with OCaml ===

OCaml can be used in nix-shell scripts as follows:

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</syntaxHighlight>

== Using Emacs ==

=== Using Emacs ===

[https://github.com/ocaml/tuareg Tuareg] is an Emacs OCaml mode. It can be installed with

<code>nix-env -iA nixpkgs.emacsPackagesNg.tuareg</code>.

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</syntaxHighlight>

== Specific version of the OCaml compiler ==

=== Specific version of the OCaml compiler ===

Various versions of the '''ocamlPackage''' attribute set are available, corresponding to various versions of OCaml. For instance, the attribute set '''ocaml-ng.ocamlPackages_4_04''' contains the OCaml compiler at version 4.04 and OCaml libraries compiled with that particular compiler.

=== Custom version ===

==== Custom version ====

So as to get the set of OCaml libraries built with/for a custom version of the OCaml compiler, e.g., to enable '''flambda''' support, you may use the '''ocamlPackages.overrideScope''' function:

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-Most packages related to OCaml, in particular the OCaml compiler and many libraries, belong to the '''ocamlPackages''' attribute set of nixpkgs.
+[[File:OCaml Logo.svg|alt=The OCaml logo: an orange background with a white foreground of a camel.|thumb|OCaml logo]]
-== Findlib, ocamlfind ==
+According to the official [ocaml.org Ocaml website]:<blockquote>
+ [Ocaml is]... an industrial-strength functional programming language with an emphasis on expressiveness and safety        </blockquote>
+== Developping in OCaml with Nix ==
+Most packages related to OCaml, in particular the OCaml compiler and many libraries, belong to the '''ocamlPackages''' attribute set of nixpkgs. Tools for OCaml development are, in particular, available:
+* the [https://dune.build/ dune] builder;
+* the [https://github.com/ocaml/ocaml-lsp OCaml language server];
+* the [https://github.com/ocaml-ppx/ocamlformat ocamlformat formatter].
+=== Build tooling ===
+Modern development practices in OCaml tend to use '''dune''', a builder dedicated for OCaml projects. Nixpkgs provide a dedicated builder: [https://nixos.org/manual/nixpkgs/stable/#sec-language-ocaml-packaging buildDuneProject].
+'''dune''' can generate a '''.opam''' file, which can be ingested by tools like [https://github.com/tweag/opam-nix opam-nix] to automatically generate a derivation.
+Manual package building is also possible using the following approaches:
+==== Findlib, ocamlfind ====
 OCaml libraries are usually located using [http://projects.camlcity.org/projects/findlib.html findlib] and the associated '''ocamlfind''' tool. These tools are found under the '''ocamlPackages.findlib''' attribute and rely on the '''OCAMLPATH''' environment variable.
@@ Line 11: / Line 31: @@
 This hook also sets the '''CAML_LD_LIBRARY_PATH''' environment variable that is used for locating the dynamically loaded shared libraries (aka stublibs).
-== Scripting with OCaml ==
+=== Scripting with OCaml ===
 OCaml can be used in nix-shell scripts as follows:
 <syntaxHighlight lang=ocaml>
@@ Line 22: / Line 42: @@
 </syntaxHighlight>
-== Using Emacs ==
+=== Using Emacs ===
 [https://github.com/ocaml/tuareg Tuareg] is an Emacs OCaml mode. It can be installed with
 <code>nix-env -iA nixpkgs.emacsPackagesNg.tuareg</code>.
@@ Line 61: / Line 80: @@
 </syntaxHighlight>
-== Specific version of the OCaml compiler ==
+=== Specific version of the OCaml compiler ===
 Various versions of the '''ocamlPackage''' attribute set are available, corresponding to various versions of OCaml. For instance, the attribute set '''ocaml-ng.ocamlPackages_4_04''' contains the OCaml compiler at version 4.04 and OCaml libraries compiled with that particular compiler.
-=== Custom version ===
+==== Custom version ====
 So as to get the set of OCaml libraries built with/for a custom version of the OCaml compiler, e.g., to enable '''flambda''' support, you may use the '''ocamlPackages.overrideScope''' function: