How to read a character in OCaml without a return key?

Question

I'm looking for something like input_char stdin but without waiting for a return key. I would not to depend on a big dependency like lambda-term.

Answer 1

Handling input in full lines is easy. Handling it a character at a time is a little bit system dependent. If you're on a Unix-like system you should be able to do this using the Unix module:

let get1char () =
    let termio = Unix.tcgetattr Unix.stdin in
    let () =
        Unix.tcsetattr Unix.stdin Unix.TCSADRAIN
            { termio with Unix.c_icanon = false } in
    let res = input_char stdin in
    Unix.tcsetattr Unix.stdin Unix.TCSADRAIN termio;
    res