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There are a lot of tutorials around monads and monad topics using Haskell because... Haskell is one of the few languages which uses monads in a principled and e

by Dewie 12y ago

There are a lot of tutorials around monads and monad topics using Haskell because... Haskell is one of the few languages which uses monads in a principled and explicit way.

pekk 12y ago
Haskell introduced monads as a way of solving certain problems Haskell had. So if you want to use Haskell effectively, you have to learn about monads. Monads are useful in Haskell. But that doesn't mean they are as useful in every language. So other languages don't NEED tutorials on monads as much as Haskell does. This isn't because those other languages are worse (less "principled" or "explicit") than Haskell. It's because they aren't structured to make it important to have tutorials on monads. Instead you worry about whatever the specific issues are for those other languages.
- Dewie 12y ago
  Yeah yeah, they are all strong independent languages that don't need no monads. What do I care. EDIT: you don't strictly need something like monad transformers, though. In general, monads are just another type class. A special one since IO is implemented with them, but other than that, they are not essential.
- codygman 12y ago
  Monads are useful and unknowingly created in other languages all the time [0]. If you aren't quite comfortable enough with monads to follow the first link, I found this implementing monads in python tutorial[1] to be a huge help. For those that want to play with Monads in Python, check out PyMonad[2]. 0: http://blog.sigfpe.com/2006/08/you-could-have-invented-monads-and.html http://blog.sigfpe.com/2006/08/you-could-have-invented-monad... 1: http://www.valuedlessons.com/2008/01/monads-in-python-with-nice-syntax.html http://www.valuedlessons.com/2008/01/monads-in-python-with-n... 2: https://pypi.python.org/pypi/PyMonad/ https://pypi.python.org/pypi/PyMonad/
- jerf 12y ago
  Expanding on the other replies, monads are not useful in most languages because most languages are not powerful enough to use them. The syntax is too heavy, because you need lots of function closures. The type system is too weak, because using monadic values without higher-kinded types is much more difficult and less useful. The fact that everybody tries to import monadic values into their languages is evidence that they would indeed be useful; the fact that such libraries are always useless in practice and incapable of even transliterating the Haskell, and often fail to even implement the full feature set of monadic values in Haskell even if you're willing to type reams of code, is why you don't use them in other languages. You don't ignore monads in non-Haskell languages because the other languages are too powerful to need them, hurr hurr Haskell is teh weaks... you ignore monads in other languages because those languages are too weak to usefully implement them. If they could, you'd see them, and I am very, very confident over the next 10 years you're going to see more and more languages coming out that really have and really use monadic values, because they will be strong enough to do so, and once you have that, the value proposition is just too good to ignore. They are too darned useful to ignore.
  - AnimalMuppet 12y ago
    > The fact that everybody tries to import monadic values into their languages is evidence that they would indeed be useful... Could you give a bit more detail here? From where I sit, I certainly don't see people trying to import monadic values into the languages I use, and I don't see much evidence that they'd be useful. (I've been trying to get my mind around monads and when and how to use them, and one of the problems I have in learning them is that, as far as I can tell, they don't look like the solution to any problem I've ever actually had.)
    - yohanatan 12y ago
      The reason you don't discern the presence of any problem is that you happily purr along as an effective 'human compiler' in a language with a [relatively] lower level of abstraction. You cannot detect that you're actually doing compilation from higher-level constructs because those higher-level concepts have not been formed in your mind (and you haven't been exposed to languages which capture those concepts more precisely/succinctly). It's quite likely, in fact, that your [manual] compilation process is not consistent or repeatable and you end up with a lower fidelity translation (i.e., with lots of noise interspersed) than a truly mechanistic compiler would.
- prakashk 12y ago
  See "The Marvels of Monads" (http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marve...), where the author talks about controlling complexity using composition, and how monads aid in accomplishing it. It's all in C#.

by Dewie 12y ago

There are a lot of tutorials around monads and monad topics using Haskell because... Haskell is one of the few languages which uses monads in a principled and explicit way.

pekk 12y ago

Haskell introduced monads as a way of solving certain problems Haskell had. So if you want to use Haskell effectively, you have to learn about monads. Monads are useful in Haskell. But that doesn't mean they are as useful in every language. So other languages don't NEED tutorials on monads as much as Haskell does. This isn't because those other languages are worse (less "principled" or "explicit") than Haskell. It's because they aren't structured to make it important to have tutorials on monads. Instead you worry about whatever the specific issues are for those other languages.

Dewie 12y ago
Yeah yeah, they are all strong independent languages that don't need no monads. What do I care. EDIT: you don't strictly need something like monad transformers, though. In general, monads are just another type class. A special one since IO is implemented with them, but other than that, they are not essential.
codygman 12y ago
Monads are useful and unknowingly created in other languages all the time [0]. If you aren't quite comfortable enough with monads to follow the first link, I found this implementing monads in python tutorial[1] to be a huge help. For those that want to play with Monads in Python, check out PyMonad[2]. 0: http://blog.sigfpe.com/2006/08/you-could-have-invented-monads-and.html http://blog.sigfpe.com/2006/08/you-could-have-invented-monad... 1: http://www.valuedlessons.com/2008/01/monads-in-python-with-nice-syntax.html http://www.valuedlessons.com/2008/01/monads-in-python-with-n... 2: https://pypi.python.org/pypi/PyMonad/ https://pypi.python.org/pypi/PyMonad/
jerf 12y ago
Expanding on the other replies, monads are not useful in most languages because most languages are not powerful enough to use them. The syntax is too heavy, because you need lots of function closures. The type system is too weak, because using monadic values without higher-kinded types is much more difficult and less useful. The fact that everybody tries to import monadic values into their languages is evidence that they would indeed be useful; the fact that such libraries are always useless in practice and incapable of even transliterating the Haskell, and often fail to even implement the full feature set of monadic values in Haskell even if you're willing to type reams of code, is why you don't use them in other languages. You don't ignore monads in non-Haskell languages because the other languages are too powerful to need them, hurr hurr Haskell is teh weaks... you ignore monads in other languages because those languages are too weak to usefully implement them. If they could, you'd see them, and I am very, very confident over the next 10 years you're going to see more and more languages coming out that really have and really use monadic values, because they will be strong enough to do so, and once you have that, the value proposition is just too good to ignore. They are too darned useful to ignore.
- AnimalMuppet 12y ago
  > The fact that everybody tries to import monadic values into their languages is evidence that they would indeed be useful... Could you give a bit more detail here? From where I sit, I certainly don't see people trying to import monadic values into the languages I use, and I don't see much evidence that they'd be useful. (I've been trying to get my mind around monads and when and how to use them, and one of the problems I have in learning them is that, as far as I can tell, they don't look like the solution to any problem I've ever actually had.)
  - yohanatan 12y ago
    The reason you don't discern the presence of any problem is that you happily purr along as an effective 'human compiler' in a language with a [relatively] lower level of abstraction. You cannot detect that you're actually doing compilation from higher-level constructs because those higher-level concepts have not been formed in your mind (and you haven't been exposed to languages which capture those concepts more precisely/succinctly). It's quite likely, in fact, that your [manual] compilation process is not consistent or repeatable and you end up with a lower fidelity translation (i.e., with lots of noise interspersed) than a truly mechanistic compiler would.
prakashk 12y ago
See "The Marvels of Monads" (http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marve...), where the author talks about controlling complexity using composition, and how monads aid in accomplishing it. It's all in C#.