There was some support for ghci on arm, but it wasn’t working
well and disabled it in Debian in 7.6.3:
* Disable GHCi on arm, as it is severly borken (for more information see
http://hackage.haskell.org/trac/ghc/ticket/7794)
Maybe things have improved in 7.8 (currently in experimental). We could
use some manpower dedicated to testing this, hunting down upstream
patches and trying them out. Unfortunately, the current 7.8 package does
not even build on arm:
https://buildd.debian.org/status/package.php?p=ghc&suite=experimental
and every developer trying to fix it gave up, mostly because the long
build times make it so annoying.