[Haskell-beginners] one more step backwards

Stephen Tetley stephen.tetley at gmail.com
Sun Jan 31 15:22:41 EST 2010

On 31 January 2010 19:53, Felipe Lessa <felipe.lessa at gmail.com> wrote:

> Along these lines we may also change evalStep using the Writer
> monad.

Hi Felipe - nice!

Bill Harrison lists DebugT (equipped with the non-proper morphism
'rollback') as one of the monad transformers in his periodic table of


I've been curious since first seeing the slides, how an implementation
might efficiently store the state...

Best wishes


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