Execute Brain****/OCaml
Quick implementation of a Brainfuck interpreter in OCaml.
Execute Brain****/OCaml is an implementation of Brainf***.
Other implementations of Brainf***.
Execute Brain****/OCaml is part of RCBF. You may find other members of RCBF at Category:RCBF.
Like the Haskell version but without the lazy lists:
Pairs of lists are used to implement both the two-side infinite band of cells, and the program storage.
run interprets a Brainfuck program and reads integers from stdin and outputs them to stdout.
A more efficient implementation could for example only admit well-bracketed brainfuck programs, and parse bracket blocks first, to replace the matchLeft and matchRight which need linear time.
# let move_left (x::l, r) = (l, x::r);; val move_left : 'a list * 'a list -> 'a list * 'a list = <fun> # let move_right (l, x::r) = (x::l, r);; val move_right : 'a list * 'a list -> 'a list * 'a list = <fun> # let rec match_left d = match d with '['::_, _ -> d | ']'::_, _ -> match_left (move_left (match_left (move_left d))) | _ -> match_left (move_left d);; val match_left : char list * char list -> char list * char list = <fun> # let rec match_right d = match d with _, '['::_ -> move_right d | _, '['::_ -> match_right (match_right (move_right d)) | _ -> match_right (move_right d);; val match_right : char list * char list -> char list * char list = <fun> # let pad = function [], [] -> [0], [0] | [], r -> [0], r | l, [] -> l, [0] | d -> d;; val pad : int list * int list -> int list * int list = <fun> # let modify f (l, x::r) = l, f x :: r;; val modify : ('a -> 'a) -> 'b * 'a list -> 'b * 'a list = <fun> # let dec x = if x = 0 then 0 else x - 1;; val dec : int -> int = <fun> # let rec exec p d = match p, d with (_, []), _ -> () | (_, '>'::_), _ -> exec (move_right p) (pad (move_right d)) | (_, '<'::_), _ -> exec (move_right p) (pad (move_left d)) | (_, '+'::_), _ -> exec (move_right p) (modify succ d) | (_, '-'::_), _ -> exec (move_right p) (modify dec d) | (_, ','::_), _ -> let c = read_int () in exec (move_right p) (modify (fun _ -> c) d) | (_, '.'::_), (_, x::_) -> print_int x; print_newline (); exec (move_right p) d | (_, '['::_), (_, 0::_) -> exec (match_right (move_right p)) d | (_, '['::_), _ -> exec (move_right p) d | (_, ']'::_), (_, 0::_) -> exec (move_right p) d | (_, ']'::_), _ -> exec (match_left (move_left p)) d;; val exec : char list * char list -> int list * int list -> unit = <fun> # let run s = exec ([], s) ([0], [0]);; val run : char list -> unit = <fun> # let char_list_of_string s = let result = ref [] in String.iter (fun c -> result := c :: !result) s; List.rev !result;; val char_list_of_string : string -> char list = <fun> # run (char_list_of_string ",[>+<-].>.");; 5 0 5 - : unit = ()