It seems that ~/.editrc isn't the right place to customize GHCi anymore, so this might help others as well. So, if you wish to set a custom keybinding or otherwise modify GHCi, you should now create a ~/.haskeline. An example would be:

bind: meta-h meta-backspace
maxHistorySize: 1000
historyDuplicates: IgnoreConsecutive

# Rudimentary autobracing
bind: { { } left
bind: ( ( ) left
bind: [ [ ] left

You can also throw in some colors in either ~/.ghci or ~/.ghc/ghci.conf:

:set prompt "\ESC[31m%s > \ESC[m"