Oh, the range notation. It's a little convenience that can save a bit of typing here and there. Not a tremendously important feature, to be honest. About multi

Oh, the range notation. It's a little convenience that can save a bit of typing here and there. Not a tremendously important feature, to be honest. About multithreading, not sure what you mean but F# definitely has parallel collections in addition to its general async capability that lets you handle concurrency in a safe way. If you haven't already, check out the Hopac project (http://hopac.github.io/Hopac/Hopac.html http://hopac.github.io/Hopac/Hopac.html , scroll down to the Description section). About memory use, yes you create copies but at the same time immutability means you can have persistent data structures which share and thus save a lot of memory. Also, in general performance is good enough that you don't really have to worry about it, and when you do, you can always measure, profile, and see what's actually causing the memory pressure. That said, it's true that functional programming languages have a different memory profile than imperative languages, and implementations which have been designed with this profile in mind perform really well. E.g. check out OCaml's performance in this GC pause benchmark: https://making.pusher.com/golangs-real-time-gc-in-theory-and-practice/ https://making.pusher.com/golangs-real-time-gc-in-theory-and...