ocaml is not a bytecode executable file (OSX)

[dcharkes]

Opening the editor gives me the following editor:

Fatal error: the file '/Users/myusername/.opam/system/bin/ocaml' is not a bytecode executable file
.
**********************************************

Error: ocaml process not operational.
Please check your installation and parameters
**********************************************

Running /Users/myusername/.opam/system/bin/ocaml in the terminal gives me a working OCaml REPL.

Why can the editor not use the ocaml executable?

[dcharkes]

Issue is the OCaml version, I was using 4.03.0.

Workaround:
opam switch 4.01.0
opam install ocaml-top

[mpodell]

Installed OCaml and OPAM via Homebrew today:
ocaml: stable 4.02.3 (bottled)
opam: stable 1.2.2 (bottled)
encountered same problem. Workaround worked for me.
Thx @dcharkes

[mpodell]

However, I could not get Core to load. It does not look like ocaml-top reads the .ocamlinit file. By explicitly adding at the prompt:
#use "topfind";;
#camlp4o;;
#thread;;
#require "core";;
#require "core.top";;
#require "core.syntax";;

I can then open Core.Std

Also, I am able to get ocaml-top to launch with a operational ocaml process under 4.02.3 by making sure my path is /Users/$USER/.opam/4.02.3/bin:$PATH instead of /Users/$USER/.opam/system/bin:$PATH (which is what my path was when I was originally having the problem described by @dcharkes above).

[dcharkes]

I got it to work with 4.02.1as well. So, it looks like it's a 4.03.0 specific problem.

[dcharkes]

@mpodell to load a module I passed an argument to the ocaml toplevel: ocaml-top --- -I ~/.opam/4.02.3/lib/adapton/.

Your solution

#use "topfind";;
#require "adapton";;
open Adapton;;

also works, but you can not use #use and #require if you want to compile the code (stackoverflow).

[infinity0]

This problem also exists with 4.02.3 Debian. The error is "correct" in the sense that .opam/system/bin/ocaml is indeed not bytecode executable. Not sure why this should block ocaml-top from using it, though.

[AltGr]

Sorry for replying so late. By default, ocaml-top will try to run ocamlrun ocaml -- which will only work with a bytecode version of the ocaml exec. Distributions apparently moved to have ocaml as a custom binary rather than pure bytecode, which break this.

Workaround: use ocaml-top -ocaml ocaml

The reason for originally running through ocamlrun has to do with Windows support, which makes process control very hard. When calling ocaml directly, there would be a new process spawned for ocamlrun, and, processes being non-hierarchichal, we would lose the handle on the child ocaml process. That took me a while to figure out at the time. There wasn't at the moment a reason to do differently on other OSes, but we could now discriminate to run through ocamlrun or not.