outline mode

[vzaliva]

I am missing a feature: an outline of the current OCaml buffer with a list of top-level definitions. There is a similar feature in Proof General mode for Coq, which I find very useful. Hence this feature request.

Below is a screenshot of how this looks in Proof General:

I get somehow similar results with imenu using helm-imenu-anywhere, but I would prefer to have an outline.