Install OCaml Compiler

Learn how to install the OCaml compiler and the REPL utop on your local machine as well as OCaml's compilation process.

OCaml compiler

The recommended way to install the OCaml compiler on a local machine is to use the package manager OPAM.

First, let’s use the following script to install OPAM:

$ sh <(curl -sL

The script checks the architecture of the computer and downloads and installs the suitable pre-compiled binary to /usr/local/bin by default.

Verify that OPAM has been installed successfully by typing in the terminal:

$ which opam

Next, follow the [instruction for installing OCaml via OPAM]( to install the latest OCaml compiler version. At the time of this writing, the latest OCaml compiler version is 4.12.0.

$ opam init
$ eval `opam env`
$ opam switch create 4.12.0
$ eval `opam env`

After this, install the following tools:

  • ocamlc: The OCaml bytecode compiler that compiles OCaml source files to bytecode files.
  • ocamlopt: The OCaml native compiler that compiles OCaml source files to native code object files and links them to produce standalone executables.
  • ocamlrun: The bytecode interpreter that executes bytecode files produced by ocamlc.

Note: Verify that the OCaml bytecode compiler has been installed successfully before continuing.

$ which ocamlc

REPL utop

A great way to learn functional programming with OCaml on a local machine is using the read–eval–print loop (REPL) utop. Use the package manager OPAM mentioned previously to install utop.

$ opam install utop

You can start utop by entering it in the shell.

$ utop

You should see something like the following screenshot:

Get hands-on with 1200+ tech skills courses.