Seems like FRP is catching on in other languages (as steveklabnik's sibling comment mentions, Javascript, and in C# and Objective C) but in Haskell it still see

Seems like FRP is catching on in other languages (as steveklabnik's sibling comment mentions, Javascript, and in C# and Objective C) but in Haskell it still seems to be a wash; there are a bunch of competing frameworks and, as far as I can tell, no clear leader. I used reactive-banana to do a school project last year, and it was ok but not on the level of Rx or ReactiveCocoa as far as I can tell. There are a half-dozen or so other frameworks, and some of them are implemented differently from others as the research moves in different directions (different ways of representing events/signals, using arrows, etc). Of course, for this specific use case (GUIs) there are similar issues in terms of implementations of GUI toolkits in Haskell (GTK? wx? some other half baked ones? and so on) But back to your other point, sure you can write imperatively in Haskell and use IO and so on, but to really take advantage of the strengths of Haskell you need to write declaratively (i.e. functionally) and take advantage of the ways that helps you write things like GUIs (which are naturally declarative).