为什么我的ocaml程序找不到模块Clflags？

Question

I am new to ocaml,I found this page: https://caml.inria.fr/pub/docs/manual-ocaml/libref/

is this page the ocaml standard lib?

when I write a program with one line:

open Marshal

ocamlc can build it

when I write

open Clflags

ocamlc give me error:Unbound module Cflags

but Clflags and Marshal are both in the list of this page

when I try to install Clflags with opam,opam tell me can't find this package

So how to use package Clflags?

Thanks

Answer 1

Cflags is a module, that belongs to the compiler-libs library, a library for compiler developers and those who are extending the compiler. So most likely, you're looking into a wrong module.

To use it, you need to add the compiler-libs folder to the search path and specify the library name that provides this module. Some automation tools will do this for you, but on the low level (for native compilation) this will look like this (assuming that your code is in the test.ml file):

ocamlopt -I +compiler-libs ocamlcommon.cmxa test.ml  -o test

Answer 2

This is not the index of the standard library, but the index of all modules provided by the standard distribution, including the compiler's front-end modules, which Clflags is a part of.

You can get the list of the standard library's modules here , and the "core", always opened module here .

Clflags isn't really useful unless you are hacking the compiler itself, which isn't really the best task for a beginner. You can find here in the documentation how to compile with it:

ocamlc other options -I +compiler-libs ocamlcommon.cma other files

But then again, you don't want to do it until you have a good grasp on OCaml and its compiler.