gistfile1.txt

let hexToByte x =
    match x with
    | '0' -> 0uy
    | '1' -> 1uy
    | '2' -> 2uy
    | '3' -> 3uy
    | '4' -> 4uy
    | '5' -> 5uy
    | '6' -> 6uy
    | '7' -> 7uy
    | '8' -> 8uy
    | '9' -> 9uy
    | 'a' -> 10uy
    | 'b' -> 11uy
    | 'c' -> 12uy
    | 'd' -> 13uy
    | 'e' -> 14uy
    | 'f' -> 15uy
    | _ -> failwith "invalid char"

let hexToBytes (x: string ) =
    String.iter : hexToByte x