Like makefile, we can define custom variables.
But I didn’t find out how to do so in dune file.
Does anyone know whether dune support this?
Dune rules can depend on environment variables.
(env_var <var>)depends on the value of the environment variable<var>. If this variable becomes set, becomes unset, or changes value, the target will be rebuilt.
https://dune.readthedocs.io/en/stable/concepts/dependency-spec.html
It doesn’t cover all cases but maybe that’s enough for you.
The short answer is “no”. However, you can often replace variables with files generated with (rule).
Cheers,
Nicolas
Thanks for your help.