Why Ocaml
OCaml is a surprisingly different language: it has both syntax and semantic features I've not seen elsewhere.
Following the Grokking​ALanguage format, let's look at features you may not have seen before.
Underrated: Tooling
Merlin is code analysis tool OCaml, offering classic IDE feaetures like go-to-definition, code completion, and type-at-cursor.
That's table stakes: Merlin has some incredible features I've not used elsewhere.
type MyList =
| Cons of (int * MyList)
| Nil
let takes_list (x : MyList) =
x
Ask Merlin to destruct x on the last line, and you get this:
let takes_list (x : MyList) =
match x of
| Cons _ -> (??)
| Nil -> (??)
This makes pattern matching a joy to use.
Merlin has some even more exotic features, such as a type-driven function search.
Overrated: Syntax
Even if you've dabbled with Haskell, OCaml has some odd bits of syntax.
[1, 2] is legal syntax, but it's not a list of a numbers. It's actually shorthand for [(1, 2)].
Precedence can be surprising too: [let y = 2 in y; 3] doesn't work as you'd expect.
This is particularly unfortunate for blocks:
if true then
f 1
else
f 2;
g 3
g 3 is unconditionally executed!
Nesting match statements can end up with a type error rather than a parse error.
Solution: I've found #ocaml on Freenode to be a great place to ask questions. ocamlformat will indent your code in a way that makes the precedence obvious too.
