# Лексический анализ
## Ссылка на видеоразбор
https://youtu.be/NKhwfK0PurY
## Код из книги
    type token = Name of string| Num of string | Other of string;;
    let lex =
        let several p = many ( some p ) in
        let lowercase_letter s = " a" <= s & s <= " z " in
        let uppercase_letter s = "A" <= s & s <= "Z" in
        let letter s = lowercase_letter s or uppercase_letter s in
        let alpha s = letter s or s = "_" or s = " ’ " in
        let digits = " 0" <= s & s <= "9 " in
        let alphanum s = alpha s or digit s in
        let spaces = s = "␣ " or s = " \n" or s = "\ t " in
        let collect (h , t) = h^( it list ( prefix ^) t " " ) in
        let rawname =
        some alpha ++ several alphanum >> (Name o collect ) in
        let rawnumeral =
        some digit ++ several digit >> (Num o collect) in
        let raw other = some (K true) >> Other in
        let token =
        (rawname | | rawnumeral | | rawother) ++ several space >> fst in
        let tokens = (several space ++ many token ) >> snd in
        let all tokens = (tokens ++ finished) >> fst in
        fst o all token s o explode;;