Visualising an Asynchronous Monad (opens in new tab)

One of the nice things about OPAM (the OCaml package manager) is that it can recompile upstream library dependencies if some new optional features gets inserted downstream. In this case, Thomas has put together a "lwt.profiling" library that adds profiling hooks, and then every upstream Mirage library gets systematically recompiled against this new functionality.

This way we can have profiling-free production code, and then just "opam install mirage-profiling" and have a coffee while everything gets instrumented. This is going to be incredible as we hook up more complex distributed unikernel-based systems.