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|
open Format
open Vstte12_combinators
let rec pr fmt t =
match t with
| S -> fprintf fmt "S"
| K -> fprintf fmt "K"
| App(t1,t2) -> fprintf fmt "(%a %a)" pr t1 pr t2
exception SyntaxError
let rec parse_term s i =
match String.get s i with
| 'S' -> S, i+1
| 'K' -> K, i+1
| 'I' -> Vstte12_combinators.i, i+1
| '(' ->
let t1,i1 = parse_term s (i+1) in
begin
match String.get s i1 with
| ' ' ->
let t2,i2 = parse_term s (i1+1) in
begin
match String.get s i2 with
| ')' -> App(t1,t2),i2+1
| _ -> raise SyntaxError
end
| _ -> raise SyntaxError
end
| _ -> raise SyntaxError
let parse_term s =
try
let t,i = parse_term s 0 in
if i <> String.length s then raise SyntaxError;
t
with _ -> raise SyntaxError
|
