type token =
Kwd of string
| Ident of string
| Int of int
| Float of float
| String of string
| Char of char
value make_lexer : string list -> (char stream -> token stream)
let lexer = make_lexer ["+";"-";"*";"/";"let";"="; "("; ")"]
The associated parser would be a function from token stream to, for instance, int, and would have rules such as:
let parse_expr = function
[< 'Int n >] -> n
| [< 'Kwd "("; parse_expr n; 'Kwd ")" >] -> n
| [< parse_expr n1; (parse_remainder n1) n2 >] -> n2
and parse_remainder n1 = function
[< 'Kwd "+"; parse_expr n2 >] -> n1+n2
| ...