[Haskell-cafe] Looking for a source level debugger

Originally sent this to /r/haskell, but it doesn't show up there for some reason, so re-sending here. Is anyone aware of a source level debugger that can be used with GHC? That is, something integrated into an editor (as a plugin, perhaps) that can highlight the line being executed, show locals, etc. (Think of WinDbg without the registers window.) I'm mostly interested in something that can work on a Linux-based system, but solutions for other platforms are welcome, too! I've heard that Sublime can run on 3 OSes, is there a solution for it, for instance? P.S. I'm not looking for opinions on whether you think a debugger is necessary or not when programming in Haskell.