Answer: Is it possible to use arrow keys in OCaml interpreter?

The stock OCaml toplevel doesn't have line editing built in. I use rlwrap:

$ cat bin/ocaml
#!/bin/sh
exec rlwrap /usr/local/bin/ocaml "$@"

Using the toplevel without something like this is quite painful, in my opinion!

Other possibilities are to run the toplevel under emacs (a popular choice, I think), or…