Prototype based OCaml
Talking about prototypes, here is a little module which allows prototype based programming in OCaml. I'll warn you right now : it's horrible, but funny.
Empty
| Obj of (string, string) Hashtbl.t * obj
let create ?(proto=Empty) () = Obj (Hashtbl.create 111, proto)
let set o k v =
match o with
Empty -> raise Not_found
| Obj (o, p) -> Hashtbl.replace o k (Obj.magic v)
let rec get o k =
match o with
Empty -> raise Not_found
| Obj (o, p) ->
try
Obj.magic (Hashtbl.find o k)
with Not_found -> get p k
There is nothing difficult to understand (it was actually difficult to do). An object is just a hashtable and a parent object. Typing is bypassed using Obj.magic
Let's have a little fun:
let _ =
let p = create () in
set p "foo" "p.foo";
set p "baz" "p.baz";
let o = create ~proto:p () in
set o "foo" "o.foo";
set o "bar" (fun f -> f (get o "baz"));
print_endline (get p "foo");
print_endline (get p "baz");
print_endline (get o "foo");
((get o "bar") : 'a->'b) print_endline;
The result:
p.foo
p.baz
o.foo
p.baz
Note : This is only a proof of concept, never use this in OCaml, it is not at all compliant with OCaml philosophy. It's funny, however 
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