This is pretty much that the GHCi debugger does expect it restores the environment at the end of a breakpoint.
I can't make any sense of what you wrote. Did you mean "what" instead of "that", and "except" instead of "expect"? In that case, it is good news to hear that it has already been done.
If you have GHC-6.6 or greater, try: let n = 2 in GHC.Base.breakpoint ()
Interesting, apparently that statement also contains the word 'print': :) $ ghci fly:~ ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.6.20070420, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done.
let n = 2 in GHC.Base.breakpoint
<interactive>:1:0: No instance for (Show (a -> a)) arising from use of `print' at <interactive>:1:0-31 Possible fix: add an instance declaration for (Show (a -> a)) In the expression: print it In a 'do' expression: print it -------- Frederik