Intro

Example d’interpréteur en OCaml

let eval expr =
  let lst = String.split_on_char ' ' expr in
  let cmd = List.hd lst in (* hd = head *) 
  let args = List.map int_of_string (List.tl lst) in
  match cmd with
  | "num" -> Some (List.hd args)
  | "add" -> Some ((List.nth args 0) + (List.nth args 1))
  | "exit" -> None
  | _ -> 
	 Printf.eprintf "Error: unknown command '%s' \n" cmd ;
	 None

let rec repl invite = 
  print_string invite ;
  match read_line () |> eval_with
  | Some n -> Printf.printf "%d\n" n ;
			  repl invite
  | None   -> Printf.eprintf "Bye.\n"

let () = repl "> "

Example d’une implémentation de map en OCaml

let rec_map f l =
  match l with
  | [] -> []
  (* tl = tail *)
  | hd :: tl -> (f hd) :: (map f tl)

ratio

exception UnknownCmd of string

let to_python expr =
  let lst = String.split on_char ' ' expr in
  let cmd = List.hd lst in
  let args = List.map int_of_string (List.tl lst) in
  match cmd with
  | "num"  -> Printf.sprintf "print(%d)" (List.hd args)
  | "add"  -> Printf.sprintf "print(%d)" ((List.hd args) + (List.nth args 1))
  | "exit" -> Printf.sprintf "exit(1)"
  | _      -> raise (UnknownCmd)

let compile ic_oc =
  let rec comp l =
    try
      let expr = input_line ic in
      Printf.fprintf oc "%s\n" (to_python expr) ;
      comp (l + 1)
    with
    | End_of_file  -> ()
    | UnknownCmd c -> (* J'ai pas fini de recopié RIP x( *)

Projet marrant qui partent de NAND pour faire quelque chose de plus cool :

• Nand2Tetris
• Nand2Raytracer
• Ben Eater (youtube)

Utiliser son language comme compilateur du language ça permet de manger sa propore merde