4 ms·

Words like 'monad' and 'kleisli category' (which I've never heard of) absolutely REEK of impracticality to me, regardless of the concepts. There's a rule for a

by jbooth 12y ago

Words like 'monad' and 'kleisli category' (which I've never heard of) absolutely REEK of impracticality to me, regardless of the concepts. There's a rule for academic papers where if the author is writing in clear language, he has something interesting to say, and if he's writing in fancy academese, he's probably saying absolutely nothing. I don't really see a huge additional value for your proposed method call semantics, can you explain more? Some(Result) can make nil go away, but you've still got the error to deal with. So you're talking some type system where a single value encapsulates Result/Nil/Error?

nine_k 12y ago
These words are merely unfamiliar. Do you think that 'pointer arithmetic', or 'open-closed principle', or 'abstract class', or 'exception propagation' sound less intimidating for a layman? But in reality none of these are complex after you've put a small effort to comprehend the notions behind them. Specifically, try reading these completely un-academic un-papers. 'Either' monad, with nice kid-friendly pictures: http://fsharpforfunandprofit.com/posts/recipe-part2/ http://fsharpforfunandprofit.com/posts/recipe-part2/ Bonus: Martin Fowler, of all men, endorses the above approach, in Java, of all languages: http://martinfowler.com/articles/replaceThrowWithNotification.html http://martinfowler.com/articles/replaceThrowWithNotificatio... A Kleisli category, with examples in down-to-earth, compact, un-hairy C++: http://bartoszmilewski.com/2014/12/23/kleisli-categories/ http://bartoszmilewski.com/2014/12/23/kleisli-categories/ This stuff is not hard and is utterly practical. It can very well be used in current industrial languages. The worst service you can render to yourself is to start thinking that you already know all what is worth knowing, and close your mind to new concepts. Guys that thought that Fortran and Cobol are enough to get by for foreseeable future were technically correct — both are still in some demand! Unfortunately, their market share has dramatically shrunk, deservedly, as have employment opportunities.
- AnimalMuppet 12y ago
  I've been trying to get my mind around this kind of stuff for maybe a year. And I have to say that monads don't look like the solution to any of the problems that I actually face or have ever faced, in a thirty-year career. So, no, it's not just that the words are unfamiliar. It's that the problems that they're trying to solve are so abstract that they're completely disconnected from the work that I actually do. And before you tell me that I'm really doing this stuff without realizing it: Maybe so. That doesn't mean that my life would be improved by doing it explicitly. It seems to me that the "everything is category theory" approach has the same over-abstraction problem that the Java "AbstractFactoryFactoryFactory" approach has, and deserves to be as frequently mocked.
  - lmm 12y ago
    When I found out about monads it was after I'd already implemented the same abstraction. It actually comes up quite a lot (async calls, error handling, audit logging, database access). http://m50d.github.io/2013/01/16/generic-contexts.html http://m50d.github.io/2013/01/16/generic-contexts.html . Just like when I was told about "the visitor pattern", my reaction was mostly "that? I've been doing that for years. So that's what it's called". Still, it's worth knowing the name for a concept so that you can talk to people about it, and it's certainly worth knowing the library tools that exist and can save you time. Pretty often I'll write two or three lines of code, look at it, and then realise "oh, that's just traverseM" or some such. Even if it doesn't save me any time writing, replacing three lines with one library call is a huge bonus to maintainability.
  - codygman 12y ago
    If you give some examples of the work that you do perhaps we can make some of the abstractions concrete.
    - AnimalMuppet 12y ago
      Perhaps you could. That's not the same as making them useful for me, though. I work primarily in embedded systems, where sequence is critical, many things are stateful, and there are multiple threads of control. So, for example, I could take the sequential aspects and re-write them as a monad. Or I could just do nothing, and let them be sequential imperative code. I know that in a pure functional world, sequence can be written as a monad. But why should I care? In my world, it does nothing for me. I'm not going to try to write imperative code in a monad to build an illusion of non-sequential purity when the essence of what I need to be doing is so sequential.
      - codygman 12y ago
        The purity is not an illusion though. Writing those sequences as a monad gives you the ability to compose actions, creating a new sequence from code you've already written for one.
LBarret 12y ago
While I understand your gut reaction, the fact that those words are unknown to you does not imply that they cover complicated concepts. It's just a new word, nothing more. it has nothing to do with . Monad is just a way to establish a (type verified) set of rules for a sequence of functions. This set of rules can be -for example- about the management of return value of these functions : executing the next function if we get a result, returning immediately if we have an error. What is powerful with Monads, is their genericity. They can be applied to many different contexts, and still provide the same type safety. You're likely already building very limited/specific monads without knowing it.
Chinjut 12y ago
Why should words you've never heard of reek of anything to you? You've never heard of them; you have no idea what they mean!

by jbooth 12y ago

nine_k 12y ago

These words are merely unfamiliar. Do you think that 'pointer arithmetic', or 'open-closed principle', or 'abstract class', or 'exception propagation' sound less intimidating for a layman? But in reality none of these are complex after you've put a small effort to comprehend the notions behind them. Specifically, try reading these completely un-academic un-papers. 'Either' monad, with nice kid-friendly pictures: http://fsharpforfunandprofit.com/posts/recipe-part2/ http://fsharpforfunandprofit.com/posts/recipe-part2/ Bonus: Martin Fowler, of all men, endorses the above approach, in Java, of all languages: http://martinfowler.com/articles/replaceThrowWithNotification.html http://martinfowler.com/articles/replaceThrowWithNotificatio... A Kleisli category, with examples in down-to-earth, compact, un-hairy C++: http://bartoszmilewski.com/2014/12/23/kleisli-categories/ http://bartoszmilewski.com/2014/12/23/kleisli-categories/ This stuff is not hard and is utterly practical. It can very well be used in current industrial languages. The worst service you can render to yourself is to start thinking that you already know all what is worth knowing, and close your mind to new concepts. Guys that thought that Fortran and Cobol are enough to get by for foreseeable future were technically correct — both are still in some demand! Unfortunately, their market share has dramatically shrunk, deservedly, as have employment opportunities.

AnimalMuppet 12y ago
I've been trying to get my mind around this kind of stuff for maybe a year. And I have to say that monads don't look like the solution to any of the problems that I actually face or have ever faced, in a thirty-year career. So, no, it's not just that the words are unfamiliar. It's that the problems that they're trying to solve are so abstract that they're completely disconnected from the work that I actually do. And before you tell me that I'm really doing this stuff without realizing it: Maybe so. That doesn't mean that my life would be improved by doing it explicitly. It seems to me that the "everything is category theory" approach has the same over-abstraction problem that the Java "AbstractFactoryFactoryFactory" approach has, and deserves to be as frequently mocked.
- lmm 12y ago
  When I found out about monads it was after I'd already implemented the same abstraction. It actually comes up quite a lot (async calls, error handling, audit logging, database access). http://m50d.github.io/2013/01/16/generic-contexts.html http://m50d.github.io/2013/01/16/generic-contexts.html . Just like when I was told about "the visitor pattern", my reaction was mostly "that? I've been doing that for years. So that's what it's called". Still, it's worth knowing the name for a concept so that you can talk to people about it, and it's certainly worth knowing the library tools that exist and can save you time. Pretty often I'll write two or three lines of code, look at it, and then realise "oh, that's just traverseM" or some such. Even if it doesn't save me any time writing, replacing three lines with one library call is a huge bonus to maintainability.
- codygman 12y ago
  If you give some examples of the work that you do perhaps we can make some of the abstractions concrete.
  - AnimalMuppet 12y ago
    Perhaps you could. That's not the same as making them useful for me, though. I work primarily in embedded systems, where sequence is critical, many things are stateful, and there are multiple threads of control. So, for example, I could take the sequential aspects and re-write them as a monad. Or I could just do nothing, and let them be sequential imperative code. I know that in a pure functional world, sequence can be written as a monad. But why should I care? In my world, it does nothing for me. I'm not going to try to write imperative code in a monad to build an illusion of non-sequential purity when the essence of what I need to be doing is so sequential.
    - codygman 12y ago
      The purity is not an illusion though. Writing those sequences as a monad gives you the ability to compose actions, creating a new sequence from code you've already written for one.

LBarret 12y ago

While I understand your gut reaction, the fact that those words are unknown to you does not imply that they cover complicated concepts. It's just a new word, nothing more. it has nothing to do with . Monad is just a way to establish a (type verified) set of rules for a sequence of functions. This set of rules can be -for example- about the management of return value of these functions : executing the next function if we get a result, returning immediately if we have an error. What is powerful with Monads, is their genericity. They can be applied to many different contexts, and still provide the same type safety. You're likely already building very limited/specific monads without knowing it.

Chinjut 12y ago

Why should words you've never heard of reek of anything to you? You've never heard of them; you have no idea what they mean!