On Jun 19, 2010, at 1:48 PM, Heinrich Apfelmus wrote:
In my code, mzero is indeed an identity for orElse [...]
The observation is any action can be brought into one of the forms
mzero
return a `mplus` return b `mplus` ...
which corresponds to the list type [a] .
Ok that makes sense because the list types supports both a cancelling
`orElse` and a distributive `mplus` with identity `mzero`.
[...] you can implement your type as
newtype CMaybe a = CMaybe { forall b . (a -> [b]) -> [b] }
Yes. For me it was interesting to see how far we get by wrapping
`Maybe` in `Codensity`: we get more than `Maybe` but not as much as
`[]`.
Sebastian
--
Underestimating the novelty of the future is a time-honored tradition.
(D.G.)
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