wxhaskell

I am experimenting with wxHaskell. I wasn't able to run the app under ghci, so I have to use application to test it. I wanted to test the program with println debugging. However, it seems that putStrLn doesn't work in GUI: {-# LANGUAGE Haskell2010 #-} module Main where import Graphics.UI.WX drawUI dc view = do circle dc (point 10 10) 5 [penKind := PenSolid, color := red] putStrLn "painted" helloGui :: IO () helloGui = do f <- frame [ text := "Example", resizeable := False, bgcolor := white, layout := space 400 300, on paint := drawUI] return () main :: IO () main = do putStrLn "Started" start

I'm trying to run an example using EnableGUI function . % ghci -framework Carbon Main.hs *Main> enableGUI >> main This is what I get instead of a working program: 2013-01-14 00:21:03.021 ghc[13403:1303] *** Assertion failure in +[NSUndoManager _endTopLevelGroupings], /SourceCache/Foundation/Foundation-945.11/Misc.subproj/NSUndoManager.m:328 2013-01-14 00:21:03.022 ghc[13403:1303] +[NSUndoManager(NSInternal) _endTopLevelGroupings] is only safe to invoke on the main thread. 2013-01-14 00:21:03.024 ghc[13403:1303] ( 0 CoreFoundation 0x00007fff8c8ea0a6 __exceptionPreprocess + 198 1 libobjc.A.dylib

Which is better for developing GUI applications with Haskell, wxWidgets (via wxHaskell ) or GTK (via Gtk2HS )? What are the pros and cons of each? Does it vary depending on which platform you are targeting (I would primarily be working on OS X but would like my programs to work on Linux and Windows too)? [Disclaimer: I am a wxHaskell maintainer] Both are stable and fairly complete GUI bindings, and you could choose either for most projects with confidence. Both have some degree of 'higher-level' Haskell bindings, but in both cases you will need to drop into rather imperative 'C' style coding