On Jul 17, 2009 1:40pm, Thomas Hartman wrote: > my question to all 3 (so far) respondants is, how does your > > explanation explain that the result is the power set? > >

I guess you forgot to reply to the cafe.

`Well, to me the modified definition I posted looks like the essence of`

`powerset, the set of all subsets. Every element x of the input list`

`divides the powerset in 2 halves, the first one contains x, the second`

`one doesn't. Filtering on the non-deterministic predicate (\x -> return`

`True `mplus` return False) in the List monad does exactly that.`

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