Regular Expressions in OCaml

问题

I want to use regexps in OCaml and it seems that Str module provides these functionalities.

So I tried with a simple program:

open Str
let regx = regexp "."

but it gives me the following error

File "lol.ml", line 1, characters 0-1: Error: Error while linking lol.cmo: Reference to undefined global `Str'

As if module is not present but if I remove open Str it says that regexp is an unbound value.

I don't get what kind of issue it is, Str should be a standard module (according to http://caml.inria.fr/pub/docs/old-311/libref/Str.html) so I'm clueless.. the only think I thought is that signature (mli) is present but implementation (ml) is not.

I'm running Objective Caml version 3.11.0 according to ocaml tool.

Can anyone help me figuring this out? Thanks in advance

回答1:

From the manual:

Programs that use the str library must be linked as follows:

ocamlc other options str.cma other files
ocamlopt other options str.cmxa other files

回答2:

Or you can put

#load "str.cma";;

if you are doing it in the interpreter

回答3:

As an alternative to the Str module there's also Re2.

1. Install it using opam install re2

2. Use the module in your_file.ml like this:

   open Re2.Std
   open Re2.Infix
   let change input_text = Re2.rewrite_exn ~/"change this" "to that" input_text
   let () = printf "%s" (change "change this")
   

3. Compile with ocamlbuild -use-ocamlfind -package re2 -package core -tag thread your_file.byte

来源：https://stackoverflow.com/questions/3221067/regular-expressions-in-ocaml