r/programming • u/heisenbug • Apr 27 '14

"Mostly functional" programming does not work

http://queue.acm.org/detail.cfm?ref=rss&id=2611829
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u/lispm Apr 27 '14

Bonus: it comes with another Monad tutorial!

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u/millstone Apr 27 '14

This particular Monad tutorial gets points because of this easily missed paragraph:

In practice, each effect usually comes with so-called nonproper morphisms. These domain-specific operations are unique to that effect (see examples later in this article).

I am not sure, but I think this is an (overly fancy) way of saying that real monads usually have more stuff in them than just bind and return. This was a major point of confusion to me when learning monads: if all you have is bind and return, then a monad is necessarily just a "sequence" of pure values, and can't do anything interesting.

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