Reactive Extensions (Rx) for .NET was first published in November 2009 under the short description “Rx is a .NET Library that allows programmers to write succinct declarative code to orchestrate and coordinate asynchronous and event-based programs based on familiar .NET idioms and patterns.” (See http://mng.bz/gQ31.)
I remember watching the first examples and reading the discussions. I was amazed by the elegance of the solutions and how simple they looked. Unfortunately, when I sat down and tried to use Rx, things were harder than I thought, and the mental change I needed to make toward reactive programming was significant. In those days, there wasn’t a lot of material on the subject, and I had to struggle to solve my issues and learn things the hard way with a lot of trial and error.