camlboot: An OCaml bootstrap experiment

camlboot is an experiment on the boostraping of the OCaml compiler. It is composed of:

• An interpreter of OCaml, in the directory interpreter/, which is able to interpret the OCaml compiler. This interpreter is written in a subset of OCaml called miniml, for which a compiler is available as part of the experiment.
• A compiler for miniml, in the directory miniml/compiler/. This compiler compiles miniml to OCaml bytecode, which is then executed by the OCaml runtime. It is written in scheme (more specifically, guile), since the goal is to bootstrap OCaml. Note that guile is itself bootstrapped directly from gcc, and building OCaml needs a C compiler as well, so we effectively bootstrap OCaml from gcc.
• A handwritten lexer for the bootstrapping of ocamllex, in the directory lex/. This lexer is able to perform the lexing of ocamllex's own lexer.mll, the first step towards the bootstrap of ocamllex, and then OCaml.

Compilation:

After cloning, you first need to clone the ocaml/ submodule, with git submodule init && git submodule update --recursive. You will also need a C compiler, and guile.

Then you can perform make -j$(nproc) _boot/ocamlc && make -j$(nproc) fullboot, which will compile a bootstrap compiler, and use it to fully bootstrap OCaml from sources. The resulting bytecode should be bit-for-bit compatible with the one you can get by compiling the code in the ocaml-src/ submodule with its own bundled bootstrap compiler. Expect this to take some time: on an 8-core machine, it took about 16 hours of CPU time, and 4 hours of wall-clock time.