direnv is mentioned in the official OCaml documentation, so having a formal way for direnv to layout does not seem like a bad idea. I often have projects that use OCaml with Node.js, and I just wanted to use layout node and layout opam together, but in the long run it's pretty convenient to be able to maintain changes on the opam side in one place.

sounds good!

Gentle ping

If opam switch is not initialized, this error will happen, but the OPAMSWITCH variable is exposed, so opam will definitely not point to any different switch and will not cause unexpected behavior.

❯ direnv allow

direnv: loading ~/src/github.com/kuis-isle3sw/IoPLMaterials/.envrc
[ERROR] The selected switch /Users/smorimoto/src/github.com/kuis-isle3sw/IoPLMaterials is not installed. Please fix the value of the OPAMSWITCH environment variable, or use the '--switch <name>' flag
direnv: export +OPAMSWITCH

@zimbatm Ready to merge!

@zimbatm Thank you for your review and the effort you put into creating and maintaining this software!

@zimbatm Could you create a new release for this PR?

Gentle reminder