OCaml Style guide?

This might be a FAQ: is there a definitive style guide out there for OCaml?

(If one googles for it, the first hits are from some classes at Cornell and U. Penn, and I don’t think those are “definitive”.)


I quite like https://ocaml.org/learn/tutorials/guidelines.html


Just started reading it. It has a lot of good stuff, though it seems a bit silent on a few things I’d like answers on. (For example, what’s preferred, begin ... end vs ( ... ), and when?) But I’ll should try to read the whole thing before making such comments. :slight_smile:

I’ve found https://github.com/hammerlab/style-guides/blob/master/ocaml.md to be a useful supplement to @techate’s link above.


There is the ocamlformat ( https://github.com/ocaml-ppx/ocamlformat ) style; the advantage with this one is that it can plug in to your editor and auto-format your code for you, like gofmt, etc.

I think (but I haven’t tried it) Emacs’ tuareg-mode also autoformats your code while you type.

And finally of course, there is refmt which autoformats ReasonML code if you write in that syntax.

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Hardly definitive, but we just posted our style guide here:


I think there is a typo here, a missing |:

match/with expressions

Put ‘ 	’ before the first pattern, e.g.:


Another one:

let position_change function

In general, this is a nice and sane guide. Will be a great benefit to incoming OCamlers. The Xen one is also fairly good https://wiki.xenproject.org/wiki/OCaml_Best_Practices_for_Developers

Under “Directory Names,” there’s a sentence that looks like it was meant as an editor’s note:

Is there guidance for organizing projects around lib/ and bin/ directories?

Thanks all for pointing out the issues. Should be fixed now.


Just reporting another typo I noticed:

The order argument to List.iter in the second code snippet should be orders (to match the first code snippet).