There is a flag to do this, and it's even In The Manual!

http://haskell.org/ghc/dist/current/docs/users_guide/ghci-set.html#id313085

  3.8.1. GHCi options

   GHCi options may be set using :set and unset using :unset.

   The available GHCi options are:

   +r

Thanks Stefan,

I just tried the ":set +r" trick. It looked really promising but it doesn't seem to work as expected.

The session with the ":set +r" is exactly the same as without it:

Prelude> :l debug68.hs
[1 of 1] Compiling Main ( debug68.hs, interpreted )
Ok, modules loaded: Main.
*Main> :set +r
*Main> :b qsort
Breakpoint 0 activated at debug68.hs:(1,0)-(3,55)
*Main> main
Stopped at debug68.hs:(1,0)-(3,55)
_result :: [a] = _
[debug68.hs:(1,0)-(3,55)] *Main> :del *
[debug68.hs:(1,0)-(3,55)] *Main> :cont
[0,1,3,4,8,11,18,23]
*Main> :b qsort
Breakpoint 1 activated at debug68.hs:(1,0)-(3,55)
*Main> main
[0,1,3,4,8,11,18,23]

Best regards,

Olivier.