Re: [Caml-list] use of ";;" when teaching Ocaml

[Philippe Wang <mail@philippewang.info>]

Apart from the ";;" thing, if you teach to beginners (well, actually
it could help experimented programmers as well), I suggest to make
function signatures explicit, meaning:
write
let f (x : int) : int = x + 1
instead of
let f x = x + 1
or
let rec map (f : 'a -> 'b) (l : 'a list) : 'b list = ...
instead of
let rec map f l = ...

for two main reasons:
1. it helps if there are bugs! Bugs are easier to find when we tell
the type checker what we expect.
2. it helps the students, because type inference is not that helpful.

But, I wouldn't force students to write those type annotations, except
perhaps the first few weeks...

Note that I would totally avoid this style:
let rec map : ('a -> 'b) -> 'a list -> 'b list = fun f l -> ...
(not that I don't like it, but I believe the other one is a lot more
efficient, pedagogically speaking)


Cheers,
Philippe Wang