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SDK Extension for OCaml stable

This extension contains various components of the OCaml stable toolchain.

Includes the Dune build system and the OCaml Package Manager opam.

Create Flatpak OCaml applications

Several examples on how to Flatpak OCaml applications leveraging this SDK can be found here.


In order to use this extension in a Flatpak SDK environment you may add all provided tools in your PATH by executing first:

$ source /usr/lib/sdk/ocaml/enable.sh

Install packages interactivelly

Initializing the Environment

In order to interactivelly install OCaml Package Manager (opam) packages in a Flatpak environmment you will need to initialize a new environment:

$ opam init --disable-sandboxing --no-setup --root $XDG_DATA_HOME/ocaml

Load the Environment Per Session

The environment will be forgotten after you restart the app, if you use this method

Run the following command to load the create the environment

$ eval $(opam env --root=$XDG_DATA_HOME/ocaml --switch=default --set-root --set-switch)

$ opam switch
#  switch   compiler     description
→  default  ocaml.5.1.0  default

Load the Environment Permanently

Run the following command to get the path of your environment, using vscodium as an example

$ flatpak run --command=bash com.vscodium.codium

[📦 com.vscodium.codium ~]$ echo $XDG_DATA_HOME/ocaml

Copy the output /var/home/<username>/.var/app/com.vscodium.codium/data/ocaml, and add OPAMROOT=/var/home/<username>/.var/app/com.vscodium.codium/data/ocaml as a environment variable for the app in flatseal


To use the SDK with your favourite editor:

$ sudo flatpak override --env=FLATPAK_ENABLE_SDK_EXT=ocaml com.visualstudio.code
$ sudo flatpak override --env=FLATPAK_ENABLE_SDK_EXT=ocaml org.gnu.emacs
$ sudo flatpak override --env=FLATPAK_ENABLE_SDK_EXT=ocaml io.neovim.nvim

or just use FLATPAK_ENABLE_SDK_EXT=* to load every SDK available in your system:

$ sudo flatpak override --env=FLATPAK_ENABLE_SDK_EXT=* com.visualstudio.code

When running your editor you should see something like this, i.e.:

$ flatpak run com.visualstudio.code
flatpak-vscode: Enabling SDK extension "ocaml"