OCaml Unbound Graphics Module

Graphics module is not ready by default. You need to load it manually. In toplevel:

$ ocaml
       OCaml version blahblah
# #load "graphics.cma";;
# open Graphics;;

or you can specify it at the command line:

$ ocaml graphics.cma
       OCaml version blahblah
# open Graphics;;

I do not know about Fedora but if the above fails, graphics is not really installed in your environment.

This error also appears often on Mac OS X. With Homebrew this module is disabled by default on installation, so brew install ocaml will not install the Graphics module, probably due to the XQuartz dependency.

If you run brew info ocaml, it will tell you that there's a flag, namely --with-x11, that will "Install with the Graphics module". So to install/reinstall ocaml you'll have to run:

brew install Caskroom/cask/xquartz
brew [re]install ocaml --with-x11

Finally remember to check that the instance of ocaml that is running is the one in /usr/local/Cellar/objective-caml/x.yy.z[_w]/bin, and if it isn't then prepend that url to your PATH environment variable. Also remember to restart your computer after the XQuartz installation.