Лексический анализ
Ссылка на видеоразбор
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;;