#show Monad.OPTION
-2. The program that starts up when you type `ocaml` is OCaml's Standard "Toplevel" Interactive Interpreter. There's an alternative interactive interpreter that you can try out, which some people like. It's called **utop** and [you can read about it here](https://github.com/diml/utop) or [here](https://opam.ocaml.org/blog/about-utop). To install it, you can just type `opam install utop`. I'm not so crazy about it myself. But I prefer to use *some* kind of helper program with OCaml's Standard Toplevel, because the Standard Toplevel itself doesn't let you scroll back through commands you typed previously, has only very rudimentary facilities for editing a line if you made a mistake and so on. One virtue of utop is that it does those things better, but there are also other ways to do them better. What I use is a wrapper program called **rlwrap**. Here are instructions for how to install that:
+2. The program that starts up when you type `ocaml` is OCaml's Standard "[[Toplevel|/topics/week8_monads_and_modules/#toplevel]]" Interactive Interpreter. There's an alternative interactive interpreter that you can try out, which some people like. It's called **utop** and [you can read about it here](https://github.com/diml/utop) or [here](https://opam.ocaml.org/blog/about-utop). To install it, you can just type `opam install utop`. I'm not so crazy about it myself. But I prefer to use *some* kind of helper program with OCaml's Standard Toplevel, because the Standard Toplevel itself doesn't let you scroll back through commands you typed previously, has only very rudimentary facilities for editing a line if you made a mistake and so on. One virtue of utop is that it does those things better, but there are also other ways to do them better. What I use is a wrapper program called **rlwrap**. Here are instructions for how to install that:
> First, I had to upgrade the version of the "GNU readline" library on my computer. My Mac with System 10.9.5 has a version of that library, but it's too old to use with recent versions of `rlwrap`. So I downloaded [the source code for GNU readline](http://ftp.gnu.org/gnu/readline/readline-6.3.tar.gz). Double click the downloaded archive to expand it, if your browser doesn't do that automatically. Then go inside the `readline-6.3` folder in a Terminal. On a Mac, you can click on the folder in the Finder and do a Copy (or cmd-C). Then open a Terminal and type `cd` followed by a space then do a Paste (cmd-V). Then press <code><i>return</i></code>. Once you're inside the `readline-6.3` folder, type this command in the Terminal: