If you are interested mainly in the functional language aspect of OCaml and use Windows, F# is very close to OCaml in syntax/semantics, but has really good support within Visual Studio (a really good debugger for example).
Once you want to use some of the more advanced features (Modules and Functors come to mind), you can switch back to OCaml relatively easily since they are so similar.
Once you want to use some of the more advanced features (Modules and Functors come to mind), you can switch back to OCaml relatively easily since they are so similar.