On Tue, Jul 12, 2011 at 6:55 PM, Felipe Almeida Lessa < [email protected]> wrote:
> ArrowChoice's (+++) documentation [1] says that "this is in general > not a functor" [1]. What does it mean for (+++) to be or not to be a > functor? > > The same note is made for (***). If you review Ross Patterson's paper [1], you'll see a note: "Note that *** does not in general preserve composition; for example, the order in which effects occur is significant." I expect the note in Control.Arrow is an oblique reference to this 'fact'. [1] http://www.soi.city.ac.uk/~ross/papers/notation.pdf
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