I am pleased to announce the bootstrap of OCaml 4.07, using only guile and gcc! The bootstrap consists in a compiler for a small subset of OCaml, written in guile, and an interpreter for almost all features in OCaml written in that subset.
It is available here: https://github.com/Ekdohibs/camlboot/ and represents about 6k lines of code. The compilation takes about four hours on a parallel machine. Many thanks to Gabriel Scherer and Julien Lepiller, who contributed significant parts of the code.