Scion provides a way for emacs to chat to ghc, giving you nice squiggly red lines under your errors in realtime.
I thought I’d found a string encoding problem in scion, but after taking a long route (tcpdump etc) it turns out that it’s just a poor default. Out of the box, scion will assume that scion server (and in turn, ghc) speaks latin1. However, you can just add this to your .emacs to make it speak utf8 instead:
(setq scion-net-coding-system 'utf-8-unix)
Now your lambdas can be λ’s and you still get pretty error messages in scion!