Comment by themckman

For those interested, some of the underlying libraries that make up Docker for Mac (and, I think, Windows) are written in OCaml (or have components written in OCaml): VPNKit[0], DataKit[1] and HyperKit[2] (qcow2 support is implemented in OCaml).

0: https://github.com/moby/vpnkit

1: https://github.com/moby/datakit

2: https://github.com/moby/hyperkit