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Comment by ernst_klim | Hacker News Reader

>I find OCaml's syntax to be quite gnarly

What's wrong with the OCaml syntax? It's much more clean than say scala's one, it's indentation insensitive, and a' list feels more relevant than the list<'T>

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It's a lot of little random things. For example, the ~keyword: syntax, the need to paranthesize where other languages don't (e.g.: "foo -1" doesn't work, you have to do "foo (-1)"). The way argumentless functions must be declared with "function". The expression termination issue (";;") is a lot less elegant than, say, Haskell's whitespace awareness. Operators not being overloaded is annoying, although there's a valid argument for explicitness.

Overall, it's not a terrible syntax, but it feels a lot like someone just invented things along the way as they needed them, without a cohesive plan. Lots of pragmatic but visually ugly choices.

I also take issue with the tooling; things like error messages, or just the antiquated feel of the CLI tools. For example, having a REPL without built-in readline support (rlwrap to the rescue) in this day and age is not acceptable.

>The way argumentless functions must be declared with "function".

Could you show an example, I don't get it?

>The expression termination issue (";;")

Strange, I've never used ";;" in my code, only in repl.

>Operators not being overloaded is annoying, although there's a valid argument for explicitness.

Overloading is harmful. It's definitely the wrong way to do ad-hoc polymorphism, and OCaml have a polymorphic comparison operators, which brought so much headache. Type classes or modular implicits are the right way to do ad-hoc. Looking forward to see modular implicits in OCaml [1].

>For example, having a REPL without built-in readline support (rlwrap to the rescue)

What do you mean by "readline" support?

[1] http://ocamllabs.io/doc/implicits.html

OCaml doesn't have argumentless functions.. But they do have functions that take a 'unit' argument.

I know, I've asked about this:

>The way argumentless functions must be declared with "function".

function is just a sugar for fun+match, what does it have to do with argumentlessness?

I think by "argumentless function" OP just means "a function taking a single, unnamed argument", which is what function does as opposed to fun in OCaml (As you say, function is just sugar for (fun arg -> match arg with .... ) - it's a common enough idiom to have some sugar in the syntax).

Sorry, I should have been clearer. As I'm aware you have the choice between several ways:

  let foo : unit -> unit = <code>

  let foo = function
    | <pattern match stuff>

  let foo = (function () -> <code>)

  let foo = (fun () -> <code>)

I'm not an expert, but I guess this awkwardness comes from OCaml not having a dedicated function-declaration syntax; so if you do:

  let foo = do_stuff + 42;

...then you're obviously just defining a variable, which is evaluated right away. Which means that the only way to define a "procedure"-type function that takes zero arguments is the above.

> What do you mean by "readline" support?

Readline is a library that adds a line editor to a REPL. It adds keyboard shortcuts (arrow keys etc.), history, autocompletion, and so on. Unlike almost every single REPL out there (Python, Ruby, Haskell, etc.), OCaml doesn't come with built-in support, as far as I've been able to determine. You have to run "rlwrap ocaml" to get Readline into your REPL.

You can also do this:

    let foo () = <code>

That's news to me. Thanks!

() is just an empty tuple, so yes, you can write let f () =...

>Readline is a library that adds a line editor to a REPL.

There is a great advanced REPL for OCaml if you need something beyond simple stuff:

https://github.com/diml/utop

One problem is that it is full of shift-reduce conflicts, due to a lack of an "end" token in most expressions.

The one that bugs me the most is nested match expressions, which often need to be wrapped in parenthesis.

In OCaml's expression syntax, "begin" is a synonym for left parenthesis, and "end" is a synonym for right parenthesis. So I've taken to just using "begin match e with ... end" in every situation to avoid this problem.

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