How to detect Esc key using Unix module and raw mode?

This is the code in OCaml to detect keys using the Unix module and raw mode in the linux terminal.

The only key I can't detect is ESC. There could be others, but my main goal is to detect ESC key.

Here is the code of the function:

    (* Function to read a character and recognize special keys *)    let read_character () =      let in_chan = in_channel_of_descr stdin in      let c = input_char in_chan in      if c = '\027' then        let next1 = input_char in_chan in        let next2 = input_char in_chan in        match (next1, next2) with        | ('[', 'A') -> "Up Arrow"        | ('[', 'B') -> "Down Arrow"        | ('[', 'C') -> "Right Arrow"        | ('[', 'D') -> "Left Arrow"        | ('[', 'H') -> "Home"        | ('[', 'F') -> "End"        | ('[', '3') when input_char in_chan = '~' -> "Delete"        | ('[', '2') when input_char in_chan = '~' -> "Insert"        | ('[', '5') when input_char in_chan = '~' -> "Page Up"        | ('[', '6') when input_char in_chan = '~' -> "Page Down"        | _ -> "Ignore"      else        match c with        | '\n' -> "Enter"        (* Handle Enter key *)        | '\127' -> "Backspace"  (* Handle Backspace (DEL) *)        | _ -> String.make 1 c   (* Return single character *)

Please, take into account that C/curses works, but it is very slow to initialize/finish and it clears the screen, so it is not an optimal option.

It is kind of a challenge. AI suggested me using Lwt/Async, but none of that worked, since I didn't have success installing that in Arch Linux.