“Eval” a string in OCaml

Question

I\'m trying to \"eval\" a string representing an OCaml expression in OCaml. I\'m looking to do something equivalent to Python\'s eval.

So far I\'ve not been able to find

Answer 1

Here is how to do it, but I didn't tell you. (Also the Parsing module is about Parsing, not executing code)

#require "compiler-libs" (* Assuming you're using utop, if compiling then this is the package you need *)
let eval code =
  let as_buf = Lexing.from_string code in
  let parsed = !Toploop.parse_toplevel_phrase as_buf in
  ignore (Toploop.execute_phrase true Format.std_formatter parsed)

example:

eval "let () = print_endline \"hello\";;"

Notice the trailing ;; in the code sample.

To use ocamlbuild, you will need to use both compiler-libs and compiler-libs.toplevel.

Answer 2

OCaml is a compiled (not interpreted) language. So there's no simple way to do this. Certainly there are no language features that support it (as there are in almost every interpreted language). About the best you could do would be to link your program against the OCaml toplevel (which is an OCaml interpreter).