Endo-Monoid of lists = differences lists
lemming at henning-thielemann.de
Fri Jan 2 09:47:15 EST 2009
How about a function for the Endo monoid, that lifts from a single value.
toEndo :: (Monoid a) => a -> Endo a
toEndo x = Endo (mappend x)
For 'a' being a list type one would have a nice difference list. This may
also occur in the documentation - both in the ones of Monoid.Endo and the
of http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dlist .
A similar application is Peano number with efficient addition. Would also
be a nice type for ShowS.
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