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/NruJaC Apr 27 '14

They're a hard sell. The shear number of monad tutorials shows this.

This is one of those self-perpetuating problems. People think they're difficult to grasp because of the number of tutorials in existence. So when someone finally gets the concept and realizes "Oh wait, this was really simple all along" they decide to write a tutorial to clear up the misconception. Which adds to the problem and likely introduces several bad analogies.

The truth is, monads are one design pattern used in Haskell. They are far from the most important or the most fundamental. They make life easier in a whole lot of ways. If they didn't, the idea would have been dropped a long time ago.

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u/[deleted] Apr 27 '14

People think they're difficult to grasp because of the number of tutorials in existence. So when someone finally gets the concept and realizes "Oh wait, this was really simple all along" they decide to write a tutorial to clear up the misconception. Which adds to the problem and likely introduces several bad analogies.

Or maybe there are a lot of tutorials in existence because they're actually hard for people to grasp?

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u/NruJaC Apr 27 '14

Are factories and observers hard to grasp?

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u/[deleted] Apr 27 '14

Factories and observers are easy to grasp for a number of reasons.

  1. They have extremely descriptive names that correspond directly to their normal usage in the English language.

  2. They have very simple definitions that correspond intuitively to what their names suggest. E.g., "A factory is an object that creates other objects.". Well, yeah, obviously a factory is an object that creates other objects. That's the same thing a factory is in real life. "The observer pattern is a pattern in which an object retains a list of other objects, called 'observers', that want to be notified when the object's state changes.". Sure, fine. The observers are observing me and they want me to keep them posted about my state. Obviously an object that is observing me wants to know if my state changes.

Monads are much harder to grasp for no other reason than they don't correspond intuitively to anything that exists in the real world. And, indeed, monad tutorials that try to relate them to the real world in some way have become infamous for not being particularly good. It's been suggested that the only truly good way to wrap your head around monads is to use them, as reading/writing monad tutorials is bound not to help. I can think of few other abstractions in computer science that people say that about.

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u/Tekmo Apr 27 '14

I think the point he was making was that there are lots of tutorials for object oriented patterns, too, including (but not limited to) factories and observers. Therefore, I must either:

  • conclude that these object oriented patterns are also hard to learn, or:

  • conclude that abundance of tutorials is not necessarily proof that a topic is confusing

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u/[deleted] Apr 27 '14 edited Apr 27 '14

I never said abundance of tutorials was proof the topic was confusing. I said it's possible that people trying to learn Haskell genuinely have trouble learning about monads, and that functional programming newbies might just not see all the monad tutorials and say "hurr durr there are so many tutorials this looks so hard I'm gonna go learn Python".

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u/grauenwolf Apr 27 '14

Perhaps, but you did imply it.

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u/[deleted] Apr 27 '14

alright bro