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Formatting your code

Instead of giving a long style guide on how to format your OCaml code, we recommend that you use ocamlformat, which is an auto-formatter for OCaml code. Here's how.

Installing ocamlformat

To install ocamlformat, type these commands into a terminal:

$ opam update
$ opam install ocamlformat

Then type this to verify that it has been installed:

$ ocamlformat --version

The most recent version is 0.26.2, which is what you should see.

Configuring ocamlformat

Create a file in your src directory called .ocamlformat (the leading . is important!), with these contents:

profile = ocamlformat
version = 0.26.2
field-space = loose

This sets the ocamlformat profile as the one to use (there are a couple of others which don't concern us). The field-space = loose line is our personal preference; type ocamlformat --help to learn more about this.

Using ocamlformat

There are two ways to use ocamlformat from the terminal command line.

The first is just to see if the new format is acceptable to you. Say you are reformatting a file called remove_complex.ml. Then type:

$ ocamlformat remove_complex.ml

and it will output the reformatted file on the screen. Assuming this is acceptable to you, and you want to permanently change the file to the reformatted one, add the -i argument (-i means "in place" since the file is modified in place):

$ ocamlformat -i remove_complex.ml

Of course, after you've added code to this file, you may want/need to run ocamlformat again.

Note

Use of ocamlformat is optional. You're not required to use it, but if you find that formatting is a nuisance to you, go ahead and give it a try.

To learn more

The "home page" for ocamlformat is here.