ocamllex is a tool for generating scanners: programs which recognized lexical patterns in text. ocamllex reads the given input files, for a description of a scanner to generate. The description is in the form of pairs of regular expressions and Ocaml code, called rules. ocamllex generates as output a Ocaml source file which defines lexical analyzer functions. This file is compiled and linked to produce an executable. When the executable is run, it analyzes its input for occurrences of the regular expressions. Whenever it finds one, it executes the corresponding Ocaml code.
If you execute the following command with the input file named lexer.mll
ocamllex lexer.mllyou will get Caml code for a lexical analyzer in file lexer.ml