0

I wonder which is the one comfortable way to program in Ocaml (in MAC).

I am currently using the VSCode to detect the syntactic and type errors, but then I use online interpreters to compile (it creates the ml) and to run examples on it; I mean, to instantiate variables, test examples etc. For example, I use the online: https://try.ocamlpro.com/.

I know this is not the best way to do it: for instance, if a package is not integrated (let us say num), I cannot do opam install num and open it.

So I wonder which is a proper option to have both (1) the cool interface like VSCode and (2) compile + test stuff on the fly.

I think I am close with the next option: I write ocaml in the terminal and then a mode is opened:

OCaml version 4.10.2
#
#
#

...

There, I can write: #open Num;; #open List;; #let... but I do not know how to load files on it.

Someone also told me there was something called "utop", but I have looked and it seems advanced for me.

Any help is appreciated!

Theo Deep
  • 666
  • 4
  • 15
  • 1
    It is a good question but the title was misleading as it looked like a typical "opinion-based" question, so I took the liberty to rephrase it to a more direct style. I think that way you will get much better and more useful answers. But, of course, if you think that my edit is too narrow, please feel free to revert/amend it. But keep in mind, that SO favors direct questions and direct answers. I will now work on the answer to your question :) – ivg May 05 '21 at 13:04
  • My only question is, do you mean 'interactive' or 'iterative' in the title? Both of them suit this question :) – Theo Deep May 05 '21 at 13:10
  • 1
    haha) I just coined a new word, iteractive for interactive/iterative development. But yes, I probably meant interactive (but thought about iterative). Please, correct this to your taste, this will make searching for the question easier. – ivg May 05 '21 at 13:13

1 Answers1

1

This mode of development is fully supported by dune that offers dune utop command that will automatically build your project, link it with top-level and start it with all your modules (and external dependencies) available.

Now if you're not yet using dune, you might wonder how to start using it. While the dune documentation is good and thorough, nobody wants to actually spend hours learning Dune, if the only thing that they want is to play with OCaml. So here is the quick tip, to create a ready to run OCaml code, use dune init, e.g.,

dune init proj play

This will create a play folder that will have the full OCaml project skeleton fully ready to use. So let's enter it,

cd play

Now we can easily build and run our project,

dune exec play

We also have the play library in the lib folder. It is empty, but you can create any files there, and they will be available in your bin/main.ml as well as in dune utop, e.g., let's create a simple module,

(* file lib/say.ml *)

let hello () = print_endline "Hi!"

and then we can use it in our executable,

(* file bin/main.ml *)

let () = Play.Say.hello ()

and we can play in the OCaml toplevel with our libraries, e.g,

$ dune utop

and then in the utop shell

utop # Play.Say.hello ();;
Hi!
- : unit = ()

So what about vscode? So far we played in the console, but vscode together with ocaml-platform can do this without leaving the comfort of your editor. You can even select pieces of code and send the toplevel (the default key binding is Shift-Enter) that enables interactive and iterative, bottom-up development.

ivg
  • 34,431
  • 2
  • 35
  • 63
  • First of all, thanks a lot for the answer!! The idea looks exactly what I was looking for. However, I am having one problem: it does not recognise the ```dune utop``` command (has worked fine with the other ones), and sends the message: ```Library "utop" not found```. I have been searching for a solution but cannot find it, any idea? Anyway, thanks a lot again!! (Looks like the closed the question, but I do not agree with the decision) – Theo Deep May 05 '21 at 16:23
  • 1
    I would start with `opam install utop` – ivg May 05 '21 at 16:56