[Haskell-cafe] "Prompt" Monad

[Martin Hofmann]

I just came across last year's thread about Ryan Ingram's "Prompt" monad
( http://www.mail-archive.com/haskell-cafe@haskell.org/msg33040.html )
and wondered if it might be useful for debugging and program analysis
purposes. In particular, I thought about enforcing program decisions
interactively. Consider for example modifying the heuristic function of
a search algorithm at specific breakpoints.

Is this possible with the "Prompt" monad? Furthermore, could somebody
post the full code of it (and maybe a short example how to use it if at
hand)? I was not able to run the code from the previous posts and the
referring links are dead.

Thanks a lot,

Martin