threepenny-gui VS gi-atk

Maybe? https://github.com/HeinrichApfelmus/threepenny-gui

Not if you use my Threepenny-gui library. 😉

If you really want FRP, use Obelisk (based on Reflex-Dom. I will call just say "Obelisk" to refer to Obelisk's dependencies Reflex-Dom, Reflex,... too). I like the author of threepenny-gui and the library has the great advantages of not needing GHCJS (Obelisk does not need GHCJS either theoretically but I do not know how easy it currently is to make it work without) nor Nix. But the library was originally built as a non-FRP library and it has been lacking essential FRP combinators for a long time.

The threepenny-gui library is probably best if you just want a simple way to make GUIs. However, it doesn't really do desktop GUIs as such: it displays your GUI as a webpage running on localhost. However, it does work pretty well with Electron, which gives you a desktop application.

For this purpose, I normally use threepenny-gui, which can be used with Electron. (As it happens, that combination is what I’m using for my current Haskell program.)

Not that I really know anything about the package, but you might be experiencing this issue: https://github.com/haskell-gi/haskell-gi/issues/396

As far as I can tell, I haven’t explicitly set extra-prog-path to anything in particular. haskell-gi’s package.cabal doesn’t seem to have this variable set either. If it does have some value out of the ordinary, I would have no idea how to figure that out.

gi-gtk (part of the haskell-gi project) is still actively maintained and it is in LTS 18.

Excellent news! For Windows, there’s some detailed documentation on installation, which I personally think is excellent. (Though I may be biased, since I wrote some of it myself!) For Linux, I remember installation being pretty simple last time I tried it (on an Ubuntu VM, as I already mentioned), though I haven’t attempted it again lately.