7 ms·

To be fair, most programmers have no clue what a monad is. To understand what a monad is you first have to understand what a monad is. (No, that wasn't a typo.)

by Nadya 11y ago

dudul 11y ago
Ha true :) I was making a jest to say that most scala programmers don't know anything about FP and just use it for the type inference and stick to OO practices, vars, etc.
- threeseed 11y ago
  No I think almost all Scala programmers understand the basics of FP. They just don't understand / have much interest in the intermediate/advanced parts. I've seen lots of beginners take to for comprehensions, maps, filters etc pretty quickly. The problem with Scala is that at an advanced level the code can become pretty unreadable.
- k3d3 11y ago
  To be fair, I'd hardly say that not knowing what a monad is = not knowing anything about FP.
- sanderjd 11y ago
  I'm honestly curious why Kotlin hasn't gathered more steam amongst this (gigantic) group of people. It seems like there's definitely room for a "Java, but a bit nicer", but that's not what Scala is intended to be. Did Scala just start winning before Kotlin was around?
  - mindcrime 11y ago
    Did Scala just start winning before Kotlin was around? I think so. By the time I heard of Kotlin, I mentally lumped it in the basket of "just another JVM language". I mean, there are so many now, and you already had Groovy, Clojure, Scala, JRuby, and Jython pretty well established, along with a couple of dozen other niche players. Then Kotlin comes along... I don't know about most people, but I never heard anything about Kotlin that was so compelling that I felt the need to go mess with it. I mean, why what instead of Nice, or Fantom, or Gosu, or Beanshell, or Mira, etc., etc... Same thing for Ceylon. It looks like just another "also ran" to me. If the people behind these languages want people to use them, they are going to have to work hard to get the word out about whatever advantages (purported or real) they have.
    - pron 11y ago
      I'll tell you why. Because right now Kotlin is the JVM language made by the largest company outside Java and Oracle. Well, technically, Ceylon is a Red Hat project, but Red Hat is a company that's basically built on lots of very loosely-related projects (Red Hat also fund JRuby, I believe), and one cannot say "Red Hat has Ceylon's back", while Kotlin certainly has JetBrains' back. As a result, it is also the non-Java JVM language with the best IDE support, best Android support and best build-tool support.
      - mindcrime 11y ago
        Because right now Kotlin is the JVM language made by the largest company outside Java and Oracle Truth be told, I don't really find that very compelling. I mean, do programming languages always need "big company" support to be successful? I don't know. So far Scala, Clojure and Groovy have done pretty well, with varying degrees of commercial support. As a result, it is also the non-Java JVM language with the best IDE support, best Android support and best build-tool support. I guess, but here's the thing... the languages I use now (mainly Groovy and Java) have at least good enough IDE support, Android support (ok, I don't really care about that) and build-tool support. So even if Kotlin is incrementally better, or hell, even dramatically better, that stuff doesn't do a lot to sway me to Kotlin. That said, like most geeks, I like dabbling with new languages, and I am sure I'll try out Kotlin (and Ceylon) at some point. And maybe then one or the other will "wow" me. But for now, it isn't a high priority. And I expect a lot of other people are approaching it with a similar mindset.
        pron 11y ago
        > do programming languages always need "big company" support to be successful? History shows that the answer to that is a resounding yes. Aside from a couple of scripting languages (BASIC and Python), there have been exactly zero successful mainstream languages without a large company behind them. Scala, Clojure and Groovy are doing fine, but their adoption is one or two orders of magnitude less than the mainstream languages (Java, C, C++, C#).
  - zak_mc_kracken 11y ago
    > Did Scala just start winning before Kotlin was around? Scala has about 2% mind share on the JVM after ten years in existence, I would say that not only is it not winning but its time has passed. Ceylon is one year old, Kotlin is not even out yet, there is plenty of time for either of these two to gain some solid mind share. Or maybe not. Maybe Java is going to reign supreme for quite a while. Whatever the replacement of Java will eventually be, I'm pretty sure it won't be Scala.
  - andrewflnr 11y ago
    Kotlin is still in development, and the documentation is patchy. I couldn't recommend it for production usage just yet. However, having used a bit of it in an Android app, I think in a couple years it has a chance to be the canonical "java but better". At least I hope so.
  - justthistime_ 11y ago
    The thing is that while Scala's main focus is not on being "a slightly nicer Java", it does that job fairly well. There just doesn't seem to be a good point in using Kotlin, as you can tell from how fast the Kotlin proponent in this thread is changing the frame of reference. - Higher-kinded types? Better compare with Haskell! - Compilation speed? Let's pick Java, the language with the least useful typesystem! - Popularity? Let's compare Scala with Java, but compare Kotlin to Scala! - Commercial backing? Let's conveniently ignore that the language lives by the cross-subsidization of JetBrain's IDE business, instead of relying on the success of their language. Point is, there is nothing that Kotlin does substantially better that would give it a niche between Java and Scala. - Non-incremental compilation speed is not that much faster compared to Scala, and substantially slower than Java. - Most of the things regularly used in Scala cannot be expressed in Kotlin, it only makes Java idioms slightly nicer to write down. - Like in Scala, IDE support is ongoing work. - Compared to both Java and Scala, the ecosystem isn't there. Compared to Scala, Kotlin makes you pay 80% of the cost for 20% of the benefits. I predict that future Java releases will keep cannibalizing Kotlin from the bottom, while Kotlin will fail to attract developers from more expressive languages.
- coldtea 11y ago
  >don't know anything about FP Depends on how we define FP. Until 2010, when Haskell started to emerge as a HN fad, people were OK to define FP as what LISP programmers do, and didn't demand FP programmers know what a modad is, type theory or even use "immutability" everywhere... If you read discussions from 2000-2005 for example, very few people define FP as "what Haskell does".
  - tome 11y ago
    Has Haskell really been a fad here for five years? It feels like just a year or two ...
david-given 11y ago
I think a lot of the problems with monads is that they're way too low level to really get a grip on what they're for --- it's like trying to explain algebra by talking about manipulating pixels on a screen. Once I finally saw some of the things you can do with a monad rather than those useless examples based around Maybe, I had an 'aha!' moment as everything went click. No sodding idea what a monoid is, though.
- rarepostinlurkr 11y ago
  Ooo! Something I think I can answer! A monoid is just a thing that knows how to add to itself!
  - Nadya 11y ago
    My understanding of a monad is that it isn't currying or recursion though. E: I shouldn't even call it an understanding of monads. I've read at least 15+ explanations of what a monad is and still don't grok it.
    - skwosh 11y ago
      Apologies in advance for the unsolicited monad tutorial (it's my turn to be that asshole)... Firstly, saying "`X` is a monad" is the same as saying "class `X` implements the monad interface". The monad interface is usually defined with `return` and `bind`, but I think it's more instructive to borrow the terminology from JavaScript's `Promise`... * `Promise#resolve(value)` is the same as `return`, also known as `pure`. It just wraps the given value in a promise. * `Promise#then(function)` combines both `bind` (when a new Promise is constructed and returned) and the functor method `map` (when a plain value is returned). To provide a unified monad/functor interface for both `Promise` and `Array` (using `wrap` instead of `resolve): // `then` provides both `bind` and `map` depending on the return type of the given function: Promise.prototype.map = Promise.prototype.then Promise.wrap = Promise.resolve // f maps elements to arrays of elements: Array.prototype.then = function (f) { return [].concat.apply ([], this.map(f)) } Array.wrap = function (x) { return [x] } There's no intrinsic value beyond that shared interface, it just allows you to write abstractions without knowing specifically what kind of monad you're dealing with (like the "do" syntax). EDIT: BTW, I've purposely skipped a few things in this description, it's meant to be illustrative, not definitive...
coldtea 11y ago
I don't see why that should be the case though (apart from the prolification of bad, overwrought, explanations). Monads are not that exotic. People present it as "deep math" but for a mathematician for example it's kids stuff at the level you need to understand them for Haskell et al. It's like saying differential equations are some "deep voodoo math" (only monads are even simpler).
- jbooth 11y ago
  I think the bad, overwrought explanations are the whole reason. Yes, they're much simpler than differential equations. But the difference is, differential equations are the simplest way to solve some difficult problems -- monads are often the gratuitously complex way to solve simple problems.
  - iopq 11y ago
    Monads are simple ways to solve simple problems. Consider the Maybe monad - it encodes optional values in a simple way. The approach before this is to have something called "null" that would wreck your programs. Maybe monad is one of the best improvements to day-to-day programming tasks that I've personally experienced in my lifetime.
    - mafribe 11y ago
      I agree, the concept of monads is very simple, actually trivial. It's just a generalised form of function composition. But thinking monadically and abstracting monadically is extremely different from what programmers normally learn, for a start because important monads like state and exceptions are built-in features of most programming languages. Seeing that these things have a common pattern, and seeing that it may be worthwhile to abstract this common pattern takes a lot of time. The mismatch between the utter simplicity of the concept of monads, and the complicated explanations one comes across doesn't help.
kika 11y ago
To be fair, (I think) you don't need to know category theory to successfully apply FP principles and/or use any functional language. I had a great (GREAT) success at using erlang not only not knowing what monad is, but even not knowing about existence of category theory at all, leave aside monads, monoids, functors, etc. You also don't need to know category theory to understand what monad is [0] This video is all you, as a practicing programmer, need to know about monads and it's just 1 hour long. [0] https://www.youtube.com/watch?v=ZhuHCtR3xq8 https://www.youtube.com/watch?v=ZhuHCtR3xq8
OnleMeMeMe 11y ago
Monads, Monoids, Applicatives, all very simple things. Most people make it seem difficult just to show off and feel as part of an elite. Which is a shame as it prevents wider usage. James is one of the few people who don't make Monads into a mythical being. http://james-iry.blogspot.de/2007/09/monads-are-elephants-part-1.html http://james-iry.blogspot.de/2007/09/monads-are-elephants-pa...

To be fair, most programmers have no clue what a monad is. To understand what a monad is you first have to understand what a monad is. (No, that wasn't a typo.)

by Nadya 11y ago

To be fair, most programmers have no clue what a monad is. To understand what a monad is you first have to understand what a monad is. (No, that wasn't a typo.)

dudul 11y ago

Ha true :) I was making a jest to say that most scala programmers don't know anything about FP and just use it for the type inference and stick to OO practices, vars, etc.

threeseed 11y ago
No I think almost all Scala programmers understand the basics of FP. They just don't understand / have much interest in the intermediate/advanced parts. I've seen lots of beginners take to for comprehensions, maps, filters etc pretty quickly. The problem with Scala is that at an advanced level the code can become pretty unreadable.
k3d3 11y ago
To be fair, I'd hardly say that not knowing what a monad is = not knowing anything about FP.
sanderjd 11y ago
I'm honestly curious why Kotlin hasn't gathered more steam amongst this (gigantic) group of people. It seems like there's definitely room for a "Java, but a bit nicer", but that's not what Scala is intended to be. Did Scala just start winning before Kotlin was around?
- mindcrime 11y ago
  Did Scala just start winning before Kotlin was around? I think so. By the time I heard of Kotlin, I mentally lumped it in the basket of "just another JVM language". I mean, there are so many now, and you already had Groovy, Clojure, Scala, JRuby, and Jython pretty well established, along with a couple of dozen other niche players. Then Kotlin comes along... I don't know about most people, but I never heard anything about Kotlin that was so compelling that I felt the need to go mess with it. I mean, why what instead of Nice, or Fantom, or Gosu, or Beanshell, or Mira, etc., etc... Same thing for Ceylon. It looks like just another "also ran" to me. If the people behind these languages want people to use them, they are going to have to work hard to get the word out about whatever advantages (purported or real) they have.
  - pron 11y ago
    I'll tell you why. Because right now Kotlin is the JVM language made by the largest company outside Java and Oracle. Well, technically, Ceylon is a Red Hat project, but Red Hat is a company that's basically built on lots of very loosely-related projects (Red Hat also fund JRuby, I believe), and one cannot say "Red Hat has Ceylon's back", while Kotlin certainly has JetBrains' back. As a result, it is also the non-Java JVM language with the best IDE support, best Android support and best build-tool support.
    - mindcrime 11y ago
      Because right now Kotlin is the JVM language made by the largest company outside Java and Oracle Truth be told, I don't really find that very compelling. I mean, do programming languages always need "big company" support to be successful? I don't know. So far Scala, Clojure and Groovy have done pretty well, with varying degrees of commercial support. As a result, it is also the non-Java JVM language with the best IDE support, best Android support and best build-tool support. I guess, but here's the thing... the languages I use now (mainly Groovy and Java) have at least good enough IDE support, Android support (ok, I don't really care about that) and build-tool support. So even if Kotlin is incrementally better, or hell, even dramatically better, that stuff doesn't do a lot to sway me to Kotlin. That said, like most geeks, I like dabbling with new languages, and I am sure I'll try out Kotlin (and Ceylon) at some point. And maybe then one or the other will "wow" me. But for now, it isn't a high priority. And I expect a lot of other people are approaching it with a similar mindset.
      - pron 11y ago
        > do programming languages always need "big company" support to be successful? History shows that the answer to that is a resounding yes. Aside from a couple of scripting languages (BASIC and Python), there have been exactly zero successful mainstream languages without a large company behind them. Scala, Clojure and Groovy are doing fine, but their adoption is one or two orders of magnitude less than the mainstream languages (Java, C, C++, C#).
- zak_mc_kracken 11y ago
  > Did Scala just start winning before Kotlin was around? Scala has about 2% mind share on the JVM after ten years in existence, I would say that not only is it not winning but its time has passed. Ceylon is one year old, Kotlin is not even out yet, there is plenty of time for either of these two to gain some solid mind share. Or maybe not. Maybe Java is going to reign supreme for quite a while. Whatever the replacement of Java will eventually be, I'm pretty sure it won't be Scala.
- andrewflnr 11y ago
  Kotlin is still in development, and the documentation is patchy. I couldn't recommend it for production usage just yet. However, having used a bit of it in an Android app, I think in a couple years it has a chance to be the canonical "java but better". At least I hope so.
- justthistime_ 11y ago
  The thing is that while Scala's main focus is not on being "a slightly nicer Java", it does that job fairly well. There just doesn't seem to be a good point in using Kotlin, as you can tell from how fast the Kotlin proponent in this thread is changing the frame of reference. - Higher-kinded types? Better compare with Haskell! - Compilation speed? Let's pick Java, the language with the least useful typesystem! - Popularity? Let's compare Scala with Java, but compare Kotlin to Scala! - Commercial backing? Let's conveniently ignore that the language lives by the cross-subsidization of JetBrain's IDE business, instead of relying on the success of their language. Point is, there is nothing that Kotlin does substantially better that would give it a niche between Java and Scala. - Non-incremental compilation speed is not that much faster compared to Scala, and substantially slower than Java. - Most of the things regularly used in Scala cannot be expressed in Kotlin, it only makes Java idioms slightly nicer to write down. - Like in Scala, IDE support is ongoing work. - Compared to both Java and Scala, the ecosystem isn't there. Compared to Scala, Kotlin makes you pay 80% of the cost for 20% of the benefits. I predict that future Java releases will keep cannibalizing Kotlin from the bottom, while Kotlin will fail to attract developers from more expressive languages.
coldtea 11y ago
>don't know anything about FP Depends on how we define FP. Until 2010, when Haskell started to emerge as a HN fad, people were OK to define FP as what LISP programmers do, and didn't demand FP programmers know what a modad is, type theory or even use "immutability" everywhere... If you read discussions from 2000-2005 for example, very few people define FP as "what Haskell does".
- tome 11y ago
  Has Haskell really been a fad here for five years? It feels like just a year or two ...

david-given 11y ago

I think a lot of the problems with monads is that they're way too low level to really get a grip on what they're for --- it's like trying to explain algebra by talking about manipulating pixels on a screen. Once I finally saw some of the things you can do with a monad rather than those useless examples based around Maybe, I had an 'aha!' moment as everything went click. No sodding idea what a monoid is, though.

rarepostinlurkr 11y ago
Ooo! Something I think I can answer! A monoid is just a thing that knows how to add to itself!
- Nadya 11y ago
  My understanding of a monad is that it isn't currying or recursion though. E: I shouldn't even call it an understanding of monads. I've read at least 15+ explanations of what a monad is and still don't grok it.
  - skwosh 11y ago
    Apologies in advance for the unsolicited monad tutorial (it's my turn to be that asshole)... Firstly, saying "`X` is a monad" is the same as saying "class `X` implements the monad interface". The monad interface is usually defined with `return` and `bind`, but I think it's more instructive to borrow the terminology from JavaScript's `Promise`... * `Promise#resolve(value)` is the same as `return`, also known as `pure`. It just wraps the given value in a promise. * `Promise#then(function)` combines both `bind` (when a new Promise is constructed and returned) and the functor method `map` (when a plain value is returned). To provide a unified monad/functor interface for both `Promise` and `Array` (using `wrap` instead of `resolve): // `then` provides both `bind` and `map` depending on the return type of the given function: Promise.prototype.map = Promise.prototype.then Promise.wrap = Promise.resolve // f maps elements to arrays of elements: Array.prototype.then = function (f) { return [].concat.apply ([], this.map(f)) } Array.wrap = function (x) { return [x] } There's no intrinsic value beyond that shared interface, it just allows you to write abstractions without knowing specifically what kind of monad you're dealing with (like the "do" syntax). EDIT: BTW, I've purposely skipped a few things in this description, it's meant to be illustrative, not definitive...

coldtea 11y ago

I don't see why that should be the case though (apart from the prolification of bad, overwrought, explanations). Monads are not that exotic. People present it as "deep math" but for a mathematician for example it's kids stuff at the level you need to understand them for Haskell et al. It's like saying differential equations are some "deep voodoo math" (only monads are even simpler).

jbooth 11y ago
I think the bad, overwrought explanations are the whole reason. Yes, they're much simpler than differential equations. But the difference is, differential equations are the simplest way to solve some difficult problems -- monads are often the gratuitously complex way to solve simple problems.
- iopq 11y ago
  Monads are simple ways to solve simple problems. Consider the Maybe monad - it encodes optional values in a simple way. The approach before this is to have something called "null" that would wreck your programs. Maybe monad is one of the best improvements to day-to-day programming tasks that I've personally experienced in my lifetime.
  - mafribe 11y ago
    I agree, the concept of monads is very simple, actually trivial. It's just a generalised form of function composition. But thinking monadically and abstracting monadically is extremely different from what programmers normally learn, for a start because important monads like state and exceptions are built-in features of most programming languages. Seeing that these things have a common pattern, and seeing that it may be worthwhile to abstract this common pattern takes a lot of time. The mismatch between the utter simplicity of the concept of monads, and the complicated explanations one comes across doesn't help.

kika 11y ago

To be fair, (I think) you don't need to know category theory to successfully apply FP principles and/or use any functional language. I had a great (GREAT) success at using erlang not only not knowing what monad is, but even not knowing about existence of category theory at all, leave aside monads, monoids, functors, etc. You also don't need to know category theory to understand what monad is [0] This video is all you, as a practicing programmer, need to know about monads and it's just 1 hour long. [0] https://www.youtube.com/watch?v=ZhuHCtR3xq8 https://www.youtube.com/watch?v=ZhuHCtR3xq8

OnleMeMeMe 11y ago

Monads, Monoids, Applicatives, all very simple things. Most people make it seem difficult just to show off and feel as part of an elite. Which is a shame as it prevents wider usage. James is one of the few people who don't make Monads into a mythical being. http://james-iry.blogspot.de/2007/09/monads-are-elephants-part-1.html http://james-iry.blogspot.de/2007/09/monads-are-elephants-pa...