I'm Learning O'Caml!

[Null]

I'm trying to pick up O'Caml, and I must say, I'm really impressed.

I like that it's a functional language, with support for imparative and OO programming when needed.

Some code that I've written in order to teach myself:

Ocaml:

(* I'm learning O'Caml!  *) let reverse string =     let rec helper n =         match n - 1 with         | -1    -> ""         | x     -> String.make 1 (string.[x]) ^ helper x in     helper (String.length string);; let main =     let input = read_line () in     Printf.printf "%s\n" (reverse input);;

Ocaml:

type colour =     | Red     | Blue     | Green     | Yellow     | Black     | White;; class virtual shape ~(colour : colour) =     object (self)         method get_colour = colour         method virtual print : unit     end class triangle ~(colour : colour) =     object (self)         inherit shape ~colour:colour         method print = print_endline "Triangle"     end class circle ~(colour : colour) ~(radius : float) =     let pi = 4.0 *. atan 1.0 in     object (self)         inherit shape ~colour:colour         method get_radius = radius         method area = pi *. radius *. radius         method print = print_endline "Circle"     end;; let main =     let triangle = new triangle ~colour:Red in     let circle = new circle ~colour:Blue ~radius:2.4 in     triangle#print;     circle#print;     Printf.printf "%f\n" circle#area;;

[wtd]

code:

(* I'm learning O'Caml!  *) let reverse string =     let rec helper n =         match n - 1 with         | -1    -> ""         | x     -> String.make 1 (string.[x]) ^ helper x in     helper (String.length string);; let main =     let input = read_line () in     Printf.printf "%s\n" (reverse input);;

How about:

code:

let reverse string =    let sub = String.sub    and len = String.length    in       match          "" -> ""        | s -> reverse (sub 1 (len s - 1) s) ^ sub 0 1 s

Oh, and I would make this small modification to your classes:

code:

class virtual shape ~(colour : colour) =     object (self)         method colour = colour         method virtual print : unit     end

[wtd]

By the way, I think it's fantastic that you're learning O'Caml, and will help out in any way I can.