The project I've been involved with at Red Hat uses OCaml in a very procedural, imperative, workaday way. We purposely don't use fancy functional stuff, except in the very few cases where it makes sense. We also freely link to C code in the same programs.

These are programs used by large numbers of generally unaware real world users. Why would they need to know - from the outside they look and behave like C binaries.

Anyway, for some big open source projects written in OCaml, take a look:

https://github.com/libguestfs/libguestfs/blob/master/v2v/v2v... https://github.com/libguestfs/libguestfs/tree/master/sparsif... https://github.com/libguestfs/libguestfs/tree/master/resize https://github.com/libguestfs/libguestfs/tree/master/builder https://github.com/libguestfs/libguestfs/tree/master/sysprep