[WJW]

At my previous job there was a need for a microservice that would compute a PhotoDNA hash of images and then compare that to a list of "known bad" material. Since this was very CPU-intensive we opted for Crystal instead of the usual Ruby that was used for almost everything else there. When I left it was churning away at ~500 images per second (over many cores, obv).

Development was pretty smooth and it was pretty easy to get new people onboarded since it look so much like Ruby. Some caveats though:

- If you want every last bit of performance, type signatures are very needed. Otherwise the compiler will still have to determine at runtime if the argument to a function is a uint32 or a uint64 for example.

- Library support is definitely lacking compared to Ruby. For example, AWS has an official SDK for Ruby with support for everything you can think of. Crystal has a 3rd party library with support for a few services. It's just not comparable.