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I have been learning a bit of Haskell on the side recently just for the thrill of learning something completely different to the way I'm used to writing code.

by jdiez17 12y ago

I have been learning a bit of Haskell on the side recently just for the thrill of learning something completely different to the way I'm used to writing code. My two cents so far is that using Haskell for "Real World" applications is not practical (at least in my experience), but by writing small applications in Haskell you learn a lot, it changes how you think. In my opinion, learning Haskell makes you a better programmer.

mwotton 12y ago
I have a crawler downloading 160 million websites a day, almost all in Haskell. It is a much more practical language than the alternatives.
coolsunglasses 12y ago
>In my opinion, learning Haskell makes you a better programmer. No, it makes you a more dissatisfied programmer. Dissatisfied with how poor the tools in other ecosystems are. You can't take Haskell with you. Erik Meijer is wrong about this. You can't use monads productively in Python. You can try, but it doesn't work well. You need Haskell. Laziness, FP, immutability, types, the whole shebang. It all hangs together in a well designed way. Not even Scala can do FP well. https://twitter.com/bitemyapp/status/534498324296921088 https://twitter.com/bitemyapp/status/534498324296921088 https://twitter.com/bitemyapp/status/534498480430284801 https://twitter.com/bitemyapp/status/534498480430284801 https://twitter.com/bitemyapp/status/534498423870066688 https://twitter.com/bitemyapp/status/534498423870066688 https://twitter.com/bitemyapp/status/534498512398864384 https://twitter.com/bitemyapp/status/534498512398864384 https://twitter.com/bitemyapp/status/534500037901176832 https://twitter.com/bitemyapp/status/534500037901176832 To quote mwotton: "here is a lightsaber, an elegant and powerful weapon. After you practice with this, you will be much better at stick-poking." is absurd. More powerful abstractions tend to invalidate more and more combinations of terms. This means the space in which your program will be correct gets narrower and narrower. The good news is, it means your abstractions will more precisely represent the correct program you want. The bad news is, you'll want help from the computer and a well-designed language. I have a video of my Haskell workflow here: https://www.youtube.com/watch?v=Li6oaO8x2VY https://www.youtube.com/watch?v=Li6oaO8x2VY It's worth considering in this context what Haskellers mean when they talk about "type tetris".
- dragonwriter 12y ago
  > No, it makes you a more dissatisfied programmer. Maybe it makes you a more dissatistfied programmer. > You can't take Haskell with you. Erik Meijer is wrong about this. You can't use monads productively in Python. You can try, but it doesn't work well. Can you explain why? Because its my experience that monads, once you understand them even a little bit, open up a way of thinking about and addressing problems that can be productively used in most programming languages (Python certainly included). > You need Haskell. Laziness, FP, immutability, types, the whole shebang. It all hangs together in a well designed way. Certainly Haskell's very nice and hangs together fairly well (though its also got some warts.) And certainly, some people will be much more productive with Haskell than with other languages. But that doesn't mean that learning Haskell won't improve your productivity with other languages, and that the combination of available existing libraries, etc., might still make some other language a net win for a particular real-world project. > Not even Scala can do FP well. Scala is certainly less good at some things than Haskell is -- and its especially unsurprising that its not as great at FP since it deliberately compromises Haskell-style FP to support extended Java-style OO (and thereby also to interop well with Java.) > "here is a lightsaber, an elegant and powerful weapon. After you practice with this, you will be much better at stick-poking." is absurd. Except its not, either in the literal sense (lightsaber fighting, after all, is stick poking with SFX) or the figurative sense.
  - mightybyte 12y ago
    > Can you explain why? Because its my experience that monads, once you understand them even a little bit, open up a way of thinking about and addressing problems that can be productively used in most programming languages (Python certainly included). I talked about part of the answer to this question at the New York Haskell Meetup awhile back. http://vimeo.com/59215336 http://vimeo.com/59215336
    - dragonwriter 12y ago
      The criticism there doesn't seem to be about why static typing is particularly a bar to productive use of monads, just the general criticism that dynamic languages lack type safety, and so limit you to monadic operations without the safety of static languages. It also makes the mistake of asserting that, because dynamic languages lack enforced types, the definition of a monad is different in those languages is different. But the definition of a monad is the same -- and includes the Monad Laws as well as the signatures of the bind and return (or fmap and join) functions -- independent of language. And the monad laws -- which even Haskell can't enforce for user-defined monads -- are just as important to correct monad use as the type signatures of the bind/return functions. Enforcement of essential properties is useful, but its not essential to productive use as the use of Monads in Haskell itself demonstrates. Its manifestly clear that productive programming without type safety is possible, and I don't see anything there that distinguishes why that would be less true with monads.
codygman 12y ago
What "Real World" applications do you think Haskell isn't practical for? For instance, why wouldn't Haskell be practical for web development?

by jdiez17 12y ago

mwotton 12y ago

I have a crawler downloading 160 million websites a day, almost all in Haskell. It is a much more practical language than the alternatives.

coolsunglasses 12y ago

>In my opinion, learning Haskell makes you a better programmer. No, it makes you a more dissatisfied programmer. Dissatisfied with how poor the tools in other ecosystems are. You can't take Haskell with you. Erik Meijer is wrong about this. You can't use monads productively in Python. You can try, but it doesn't work well. You need Haskell. Laziness, FP, immutability, types, the whole shebang. It all hangs together in a well designed way. Not even Scala can do FP well. https://twitter.com/bitemyapp/status/534498324296921088 https://twitter.com/bitemyapp/status/534498324296921088 https://twitter.com/bitemyapp/status/534498480430284801 https://twitter.com/bitemyapp/status/534498480430284801 https://twitter.com/bitemyapp/status/534498423870066688 https://twitter.com/bitemyapp/status/534498423870066688 https://twitter.com/bitemyapp/status/534498512398864384 https://twitter.com/bitemyapp/status/534498512398864384 https://twitter.com/bitemyapp/status/534500037901176832 https://twitter.com/bitemyapp/status/534500037901176832 To quote mwotton: "here is a lightsaber, an elegant and powerful weapon. After you practice with this, you will be much better at stick-poking." is absurd. More powerful abstractions tend to invalidate more and more combinations of terms. This means the space in which your program will be correct gets narrower and narrower. The good news is, it means your abstractions will more precisely represent the correct program you want. The bad news is, you'll want help from the computer and a well-designed language. I have a video of my Haskell workflow here: https://www.youtube.com/watch?v=Li6oaO8x2VY https://www.youtube.com/watch?v=Li6oaO8x2VY It's worth considering in this context what Haskellers mean when they talk about "type tetris".

dragonwriter 12y ago
> No, it makes you a more dissatisfied programmer. Maybe it makes you a more dissatistfied programmer. > You can't take Haskell with you. Erik Meijer is wrong about this. You can't use monads productively in Python. You can try, but it doesn't work well. Can you explain why? Because its my experience that monads, once you understand them even a little bit, open up a way of thinking about and addressing problems that can be productively used in most programming languages (Python certainly included). > You need Haskell. Laziness, FP, immutability, types, the whole shebang. It all hangs together in a well designed way. Certainly Haskell's very nice and hangs together fairly well (though its also got some warts.) And certainly, some people will be much more productive with Haskell than with other languages. But that doesn't mean that learning Haskell won't improve your productivity with other languages, and that the combination of available existing libraries, etc., might still make some other language a net win for a particular real-world project. > Not even Scala can do FP well. Scala is certainly less good at some things than Haskell is -- and its especially unsurprising that its not as great at FP since it deliberately compromises Haskell-style FP to support extended Java-style OO (and thereby also to interop well with Java.) > "here is a lightsaber, an elegant and powerful weapon. After you practice with this, you will be much better at stick-poking." is absurd. Except its not, either in the literal sense (lightsaber fighting, after all, is stick poking with SFX) or the figurative sense.
- mightybyte 12y ago
  > Can you explain why? Because its my experience that monads, once you understand them even a little bit, open up a way of thinking about and addressing problems that can be productively used in most programming languages (Python certainly included). I talked about part of the answer to this question at the New York Haskell Meetup awhile back. http://vimeo.com/59215336 http://vimeo.com/59215336
  - dragonwriter 12y ago
    The criticism there doesn't seem to be about why static typing is particularly a bar to productive use of monads, just the general criticism that dynamic languages lack type safety, and so limit you to monadic operations without the safety of static languages. It also makes the mistake of asserting that, because dynamic languages lack enforced types, the definition of a monad is different in those languages is different. But the definition of a monad is the same -- and includes the Monad Laws as well as the signatures of the bind and return (or fmap and join) functions -- independent of language. And the monad laws -- which even Haskell can't enforce for user-defined monads -- are just as important to correct monad use as the type signatures of the bind/return functions. Enforcement of essential properties is useful, but its not essential to productive use as the use of Monads in Haskell itself demonstrates. Its manifestly clear that productive programming without type safety is possible, and I don't see anything there that distinguishes why that would be less true with monads.

codygman 12y ago

What "Real World" applications do you think Haskell isn't practical for? For instance, why wouldn't Haskell be practical for web development?