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Ask Slashdot: Do You Like Functional Programming? (slashdot.org) 418

An anonymous reader writes: Functional programming seems to be all the rage these days. Efforts are being made to highlight its use in Java, JavaScript, C# and elsewhere. Lots of claims are being made about it's virtues that seem relatively easy to prove or disprove such as "Its use will reduce your debugging time." Or "It will clarify your code." My co-workers are resorting to arm-wrestling matches over this style choice. Half of my co-workers have drunk the Kool-Aid and are evangelizing its benefits. The other half are unconvinced of its virtues over Object Oriented Design patterns, etc.

What is your take on functional programming and related technologies (i.e. lambdas and streams)? Is it our salvation? Is it merely another useful design pattern? Or is it a technological dead-end?

Python creator Guido van Rossum has said most programmers aren't used to functional languages, and when he answered Slashdot reader questions in 2013 said the only functional language he knew much about was Haskell, and "any language less popular than Haskell surely has very little practical value." He even added "I also don't think that the current crop of functional languages is ready for mainstream."

Leave your own opinions in the comments. Do you like functional programming?
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Ask Slashdot: Do You Like Functional Programming?

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  • It has its uses (Score:5, Insightful)

    by RightwingNutjob ( 1302813 ) on Sunday April 23, 2017 @09:55PM (#54289693)
    but I'm skeptical about functional as the hammer for every nail. Generics and lambda expressions in C++ can make some niche problems disappear entirely by making the compiler do all the work for you, Scheme and Lisp and the like are useful for some very narrow and very academic use cases. As the go-to tool in the tool box? Not so much.
    • Re:It has its uses (Score:5, Insightful)

      by beelsebob ( 529313 ) on Sunday April 23, 2017 @10:14PM (#54289761)

      There's two big things that have come out of the recent move towards more functional programming which are really important.

      1) People are understanding that reducing the amount of state that any particular bit of code carries reduces the complexity of working with it. Less state means more testability, more easy reasoning about the code, more clarity, more easy debugging, and fewer edge cases to consider. That's not to say that you should never has state, as pure functional programming would have you believe, but reducing state dependance pretty much helps make your code better universally.

      2) People are realising that inheritance is not the be-all and end-all of modelling code that the OOP world would have you believe. They're realising that inheritance is what screws up type systems, and makes them hard to work with. They're realising that deep inheritance hierarchies often lead to complex code which is tricky to understand exactly what code is going to execute when, and where you're going to jump to when you're reading it. Again - this isn't to say you should never use inheritance, but people are realising that composition can work equally well, or better, and that using it over inheritance has some substantial benefits.

      As to the bandwagon of "write javascript, it's a functional language, that makes it brilliant". Fuck off... That's just yet another of the latest fads towards pascal on trains; nodeHaskell; and reactMonkey. I'll happily sit here continuing to write ancient languages, but trying to apply some of the concepts from FP to make my code simpler and more readable.

      • by plopez ( 54068 )

        *2) People are realising that inheritance is not the be-all and end-all of modelling code that the OOP world would have you believe*

        In the GoF book they flat out state that they prefer aggregation to inheritance. There is a reason you cannot do diamond inheritance in Java. Am I the only one who got the memo?

      • Re:It has its uses (Score:5, Interesting)

        by Dutch Gun ( 899105 ) on Monday April 24, 2017 @12:25AM (#54290173)

        Few "in the OOP world" (whatever that means) promotes inheritance as the end-all-be-all these days. I think that went out of style fifteen or twenty years ago. The notion of eschewing inheritance whenever possible [wikipedia.org] has its own Wikipedia entry, and was described in detail in the famous "Design Patterns" gang of four book.

        That being said, there's a time when reality can intrude on "theoretically" clean designs or programming paradigms. Functional programming and unit testing are things you don't see widely used in the videogame development world, at least that I've seen. Not all paradigms and patterns apply to all types of problems. Ultimately, I think that's the most valuable thing I've learned over time. Use the tools and techniques most appropriate to the problem at hand you're trying to solve. Religious wars over programming techniques and methodologies are for pedantic fools.

        • by dgatwood ( 11270 )

          Functional programming and unit testing are things you don't see widely used in the videogame development world, at least that I've seen.

          I'd expect functional programming to be used quite a bit in that space, but only for very small chunks of performance-critical code, such as massively parallel bits down in the guts of raytracing engines. Now whether they actually use functional programming languages or not is another question.

          Unit testing is something you don't see widely used in software development, pe

          • very small chunks of performance-critical code, such as massively parallel bits down in the guts of raytracing engines. Now whether they actually use functional programming languages or not is another question.

            Looking at OpenCL/Vulkan/Direct3D/OpenMP/etc, the answer seems to be a clear no. The lots-of-'threads'-running-sequential-C-code model seems to work pretty well though, and programmers are essentially forced to think about state. You don't stand much of a chance messing about with globals in those environments (but I guess you could try it).

        • Re:It has its uses (Score:4, Interesting)

          by silentcoder ( 1241496 ) on Monday April 24, 2017 @06:22AM (#54290907)

          I would argue that OO remains the best paradigm we have for constructing data presentation - especially when the data represents something that exists in the real world (or a reasonable facsimile as in GUI programming or video-game dev). Functional programming on the other hand - is often the best paradigm we have for data processing, especially big data processing. Use them each in their own domains and break these rules-of-thumb whenever it makes sense to.

          • Games dev actually avoids OOP like the plague these days. Anything that runs on the GPU is purely functional, much of what runs on the CPU is purely functional, and data oriented rather than object oriented. Games devs care more about whether you can keep everything in cache, and crunch through it, rather than whether its modeled nicely.

        • by Big Hairy Ian ( 1155547 ) on Monday April 24, 2017 @07:11AM (#54291011)

          Religious wars over programming techniques and methodologies are for pedantic fools.

          Us Pastafarians would disagree! We prefer to write Spaghetti Code :D

      • Re:It has its uses (Score:4, Insightful)

        by jandrese ( 485 ) <kensama@vt.edu> on Monday April 24, 2017 @12:40AM (#54290203) Homepage Journal
        There is certainly value in reducing the amount of state you are managing, but too often it seem like Functional programmers are willing to declare it gone when they've just swept it under the rug. Sure you don't have a variable now, but instead you have the logic tied up in your stack. This is especially true when the language does pattern matches on the parameters to determine which function to call. In the end you have to keep track of that iterator somehow, and I tend to think something like a for loop tends to be clearer than looking through the function headers to figure out how the loop is initialized and when it terminates.
      • "People are realising that inheritance is not the be-all and end-all... They're realising that deep inheritance hierarchies often lead to complex code which is tricky to understand exactly what code is going to execute when..."

        I'm pretty sure it was 1990 when one of my professors said, "We used to worry about spaghetti GOTOs; now we have to worry about spaghetti inheritance".

        • by Z00L00K ( 682162 )

          And spaghetti inheritance is especially prevalent in some solutions where there's an unnecessary amount of interfaces declared - so that everything is just declared and accessed through badly documented interface items so you can't figure out how to create new objects when you need them.

          Don't get me wrong - interface declarations are good too, but they have to be documented so others can understand how the objects they carry are constructed. The overall system design strategy is also something that has to b

          • Re:It has its uses (Score:5, Insightful)

            by RightwingNutjob ( 1302813 ) on Monday April 24, 2017 @02:12AM (#54290409)
            It ain't f'ing unnecessary. If it's a spaghetti or gotos it'll be a spaghetti of inheritances or a spaghetti of lambda's. At some point, the complexity of the task the program is executing requires complex code. Goto's can be done so that they're easy to understand. So can inheritance. So can lambda's. But you've got to be aware of the fact that some things are just plain hard to understand because they're hard, no matter how good of a communicator the programmer is.
            • by fyngyrz ( 762201 ) on Monday April 24, 2017 @09:00AM (#54291295) Homepage Journal

              I would add to this that reducing the complexity by turning everything into separate functions tends to also increase what I call "opacity by non-locality."

              Not only are some things hard, some things benefit from having the logic right there in front of your face; not in a header, not in some function elsewhere, not in a library.

              Benefits in both comprehension, and so ease of construction, but also in execution time and smaller executables depending on just how smart the language is in constructing its own executables.

    • I would have expected that everyone wants functional programming. Well, except for people being specifically paid to fix up dysfunctional programming, but I'll take functional code any day of the week.
    • The computer scientist in me loves functional languages, the MBA in me doesn't.
      Functional languages makes very tight code. Which for the programmer and the computer scientist is great. Less coding, a solid routine with little effort.
      However it makes it difficult to maintain a program over a life time. As it is always near one feature away from a full rewrite, vs just slapping some if conditional in the code which while inelegant, is easy to code, easy to see the change, and easier to test.

      • by HiThere ( 15173 )

        Functional languages are a bit more difficult to think about, but that may be a combination of my inexperience and the implementations I've seen. OTOH, some problems do not deal with with lack of state. I'd really like to use Erlang, e.g., but I need mutable state. You can do it in Erlang, but you've got to fight the system to do it.

        Note: I don't need externally visible mutable state. That's clearly dangerous in a concurrent system. I need internally mutable state. In Erlang that means either storing

  • by FrankHaynes ( 467244 ) on Sunday April 23, 2017 @09:59PM (#54289699)

    seem to be the prevalent choice on the web these days.

  • by motorsabbath ( 243336 ) on Sunday April 23, 2017 @10:04PM (#54289717) Homepage

    I like functional composition, it certainly has its uses (at least as middleware). I disagree with the notion that it makes code more readable though, in general. It only makes code more readable if you're familiar with it (functional programming).

    • It only makes code more readable if you're familiar with it (functional programming).

      Well that's a truism. Object-oriented programming is the same: it only makes code more readable if you're familiar with it.

      The main distinction between the two, however, is that object-oriented programming was invented, but functional programming was discovered.

  • Scala (Score:3, Interesting)

    by Anonymous Coward on Sunday April 23, 2017 @10:05PM (#54289721)

    I prefer to use functional programming where it makes sense (most of the time). One reason I like Scala is that it's not pure. You can always write a for loop if you need to. Haskell, is a bit less forgiving.

  • by Z80a ( 971949 ) on Sunday April 23, 2017 @10:09PM (#54289729)

    Use only that which works, and take it from any place you can find it.

  • "Like"? (Score:5, Insightful)

    by eyenot ( 102141 ) <eyenot@hotmail.com> on Sunday April 23, 2017 @10:13PM (#54289757) Homepage

    I don't get what you mean by "like".

    Procedures are procedures, period.

    Sometimes it's helpful to have some procedure (or subroutine) store some value in some location before popping the stack.

    What I really don't get in this write-up is the insinuation that a focus on (purely) functional programming is a "recent trend". That implies that the majority of today's coders have no fucking idea how coding has progressed through the last few decades (which I've been there to see firsthand).

    That's the only interesting thing about this article.

    • by gl4ss ( 559668 )

      That implies that the majority of today's coders have no fucking idea how coding has progressed through the last few decades

      ..and you were unaware of this? how in the hell?

    • Re:"Like"? (Score:5, Insightful)

      by lucm ( 889690 ) on Monday April 24, 2017 @12:09AM (#54290125)

      What I really don't get in this write-up is the insinuation that a focus on (purely) functional programming is a "recent trend".

      There is a new area where functional programming does shine, and it's large scale analytics. Sometimes when you think about solving a specific problem, you can go about it in a few different ways, but almost every time if your solution later needs to be parallelized (i.e. running on a Hadoop cluster) the functional programming way will be easier to adapt.

      For instance, let's imagine a situation where you have a small e-commerce website and the marketing team wants to know what are the most common sequences of pages visited by users. You could write a quick & dirty python script that parses the logs and creates a hash of every possible sequence, then you could use that to "rank" sequences by time, browser, location, etc. Or you can play the fancy card and use something like Petri nets in a map-reduce-ish kind of way. Both approaches work.

      But then your small website becomes a big success, and grows and grows and grows, and one day your script runs out of steam. So you figure, let's run that bitch on a big Hadoop cluster. Well guess what, a script that is map-reduce friendly will be a lot easier to adapt for that.

      I'm not saying every single situation warrants for this kind of thinking. But that qualifies as a kind of problem that is fairly new for mainstream programmers.

       

      • by dgatwood ( 11270 )

        In the long run, I'd expect the tools to adapt to solve those problems more transparently, e.g. through the use of standardized libraries that hide the parallelization behind procedural wrappers so that developers can write seemingly procedural code, but gain the benefits of massively parallelized code for the pieces that matter.

        Or not; hard to say.

    • I don't get what you mean by "like".

      Procedures are procedures, period.

      Indeed they are. And purely functional programming languages don't have procedures.

      The grafting of functional programming constructs onto imperative languages is interesting and useful, but every programmer should spend some time learning to program in a purely functional style, even if they then go back to imperative languages for their everyday work. It opens up a whole new way of thinking about code.

  • by gwolf ( 26339 ) <gwolf@gwo l f . org> on Sunday April 23, 2017 @10:15PM (#54289771) Homepage

    But it seems that I will.

    Around ten years ago, I started writing a column for a magazine. My first article was precisely a way to use functional programming for "real" code, using a multi-paradigm language (Ruby).

    I didn't jump on the Functional bandwagon first time I saw it; it took me around ten years to understand and embrace what it can do. So we are talking about 20 years of hype. At least.

    I am far from proficiently thinking functionally, although I have used it for many interesting things. It is a cool, and very different, way to work. It can make many things faster and simpler, but if you completely bite the bullet and make it your dominant paradigm, it will kill your productivity (with many other things that are not best served by that paradigm.

    It has a clear spot under your programmer belt. But it should not be The Only Way to approach a program - unless you are Truly One with the Tao.

  • by reanjr ( 588767 ) on Sunday April 23, 2017 @10:18PM (#54289785) Homepage

    While I wouldn't want to program in a pure functional, no side effect language, a good mix of differing paradigms seems to me to be the way to go. Java and .NET went overboard on the OOP, and it leads to these poor abstractions in many cases (I.e. AbstractFooProcessor), which are much better approached with some FPd

    Pure functional code is super easy to reason about, though, especially asynchronous code. OOP has its role, but oftentimes you find yourself on loose footing, with its focus on always changing state. This can be addressed with good practices, which leads you down class hiearchy hell. Throwing some FP in the mix gives you (mostly) the best of both worlds.

  • by nanolith ( 58246 ) on Sunday April 23, 2017 @10:20PM (#54289797)

    Functional programming languages like Haskell, ML, and Gallina can be very beautiful. The problem is that they have a steep learning curve that has less to do with the syntax of the language and more to do with the semantics. If one is well versed in category theory or has spent a significant amount of time working with functor spaces, monoids, and monads, then it's much easier to understand a non-trivial application written in Haskell than the equivalent object hierarchy in an object-oriented language. The up-front cost is greater in terms of study and learning the semantics, but the end result is significantly more powerful.

    I love functional programming. I went from C++ to Haskell and C as my go-to languages for personal projects. However, in my professional work, I tend to factor long-term language popularity into my decisions. So, I'm more inclined to use languages like Java, C#, Go, Python, and Ruby when I'm paid to write software. I have to consider the total cost of ownership in my professional work, and part of that cost is finding people to maintain it years from now.

    I think that FP has an elegance that makes it a worthy model, and I hope that some day, FP becomes more popular than OOP. But, I'm old enough to understand that technical superiority rarely wins out to popularity. Popularity matters. This sort of calculus is one of the reasons why FP has not gained much traction despite all of the buzz.

    • If one is well versed in category theory or has spent a significant amount of time working with functor spaces, monoids, and monads, then it's much easier to understand a non-trivial application written in Haskell than the equivalent object hierarchy in an object-oriented language. The up-front cost is greater in terms of study and learning the semantics, but the end result is significantly more powerful.

      I strongly suspect (but can't yet prove) that the supposed up-front cost in understanding Milner-esque functional languages is just the same as the up-front costs for Simula-style object oriented languages. The difference is that in the case of Simula-style object oriented languages, most of the up-front cost has already been largely paid by the time you come to them.

      If it's any help, consider that there seems to be a significant learning cost in wrapping your brain around "real" object-oriented languages s

      • by nanolith ( 58246 ) on Monday April 24, 2017 @12:06AM (#54290117)

        I don't disagree with your assessment. However, if your assessment is valid, then a functional language is still going to be quite foreign to someone who has only been taught object-oriented programming. I agree that we can go deep down the rabbit hole with OOP as well. The minimal interface that has been extracted from the science behind OOP and introduced to programmers in general is a mere shadow of the works of folks like Barbara Liskov.

        FP has yet to have this generational winnowing. It is still fresh and academic. We can build people up to understand this, or we can pull these concepts down to their most basic versions that are still useful. I suspect that both will have to happen before the industry can meet in the middle with FP. We are seeing this happen already as mainstream languages are adopting bits and pieces of functional concepts. I think it's more likely that we will see functional applications of OOP, such as in languages like Scala, than OOP superseded by FP. That's okay. There are already plenty of examples of non-mutable objects with copy-on-write semantics. We are seeing functions treated more and more like first-class objects. There are examples of the FP-as-style movement taking off.

        I believe that we should teach higher math in high school and even as a requirement for engineering or information systems disciplines. Currently, most universities top out bachelor degree seeking students specializing in these disciplines to calculus, differential equations, and linear algebra if they are lucky. It would be nice to see abstract algebra and some category theory taught as well. When I advise people genuinely interested in pursuing software development as a career, I strongly recommend that they minor in mathematics so they can have the opportunity to take these more advanced classes.

        That being said, there's nothing that prevents people from studying this for self-improvement. Learning either or both OOP and FP will fundamentally change the way that one organizes software. I'd love to see high school kids exposed to these concepts and the mathematics behind them. Then again, I'd also love to see high school kids taught how to build their own CPUs from 74-series logic ICs. Understanding the theory of computation at an intuitive level will do incalculable good for most of these kids through the rest of their careers. If I were to teach a class to high school level students, it would be along this line. I can guarantee that they will never look at a computer, embedded device, or "smart" device the same way again.

  • Wrong question (Score:4, Insightful)

    by gweihir ( 88907 ) on Sunday April 23, 2017 @10:23PM (#54289805)

    The right question would be "Do you understand functional programming?". And when you see about 99% of all "coders" having no clue, then you could ask the rest why they invested the time.

    • A more basic question: "Do you understand recursion?" Lot of programmers really struggle with recursion, and avoid it like the plague. A common mistake is thinking that exiting the function means exactly that, rather than exiting only the current invocation of the function.
  • by corporate zombie ( 218482 ) on Sunday April 23, 2017 @10:35PM (#54289839)

    Wow. Really?

    Functional programming.

    1. Prefer non-mutable data. No more action at a distance bugs. Hand off a reference to your data structure and don't have to care. Replay any data transform at any point as a unique structure.
    2. Prefer a defined and well known API often involving transforms that take a function as an argument to provide the predicate (e.g., filter), transform (e.g., map), aggregation (e.g., foldLeft/Right), or whatever building block.
    3. Prefer data structures that you can reason about based on a well-known set of patterns. (Best quote ever: "You say `patterns' and everyone is warm and fuzzy. You say `monad' and every loses their f-ing minds.)

    Given (2) in a language you'll often see in a language that functions are first-class data.

    Functional programming is just (a set of) best-practices. It's scary when the big words are new. Once you use it a bit you'll wonder why when you say, "use a flatMap", folks freak out because all you've said is, "You are transforming the elements of some container into values that are themselves an instance of the same container but you want to flatten everything back from nested containers. [E.g., Container is C with element type A; thus C[A]. You've run a transform that will create C[C[A]] but want to end up with C[A] at the end]." Now you could say that second part but that's a lot of words. Because of points (2) and (3) above we just say, "use a flatMap" (or however you spell `bind` in your language of choice).

    Nothing to see here. Please move along. (And yes. I like functional programming. A lot.)

    • by mikaere ( 748605 )

      I'm a C# and BI developer I was paid to learn Clojure (a LISP) for a cloud-based contact centre platform project. I really liked it, but it did take me a while to get my head around the different patterns

      If you have a problem that can be solved using functional programming (e.g. operating on sets of data) then it can be a good choice. For example, I reckon it would be extremely useful in a business intelligence transformation layer.

  • Not sure whether that was an intended pun or not, but I'm using it...

  • by brian.stinar ( 1104135 ) on Sunday April 23, 2017 @10:37PM (#54289849) Homepage

    I got my master's degree with this guy [unm.edu], and I had to take a Haskell course, or seminar, every semester. I was, and still am, pretty terrible at Haskell.

    However, what I attempted to learn helped my Python out a lot. Map and filter are two of my favorites, and the other functional paradigms [python.org] are occasionally useful to me as an actually working, productive, programmer. I'm happy I was exposed to those concepts, since they tend to come in handy. Yes, everything is Turing complete, and you can accomplish the same things without functional programming, or without high level language, or without computers [xkcd.com], but that doesn't mean they are all equally useful to solving the problem at hand.

    I recommend everyone become familiar with functional concepts in some way, if only to make them more well rounded. I don't advocate writing your next web application in Haskell though...

  • It's a very useful way of thinking about certain problems and it is often simpler that a lot of pattern heavy code. Take something like a template method. With functional programming just provide the functions to the method or instance. It accomplishes the same thing without an explosion of subclasses.

    There's a lot of other classic OO patterns that aren't needed or just done a lot more cleanly with higher order functions and other functional programming paradigms. It's also unfortunate that people assume fu

  • Not a panacea by any means. Sometimes it's harder to apply to general business programming in a meaningful and useful way - immutable objects aren't necessarily the best fit for data objects, to my mind anyway. Applied correctly and maybe less-than-completely the patterns and thinking from functional programming can be a good thing - but I'm not really a fan of pure functional programming and prefer the hybrid approaches like Scala.

  • Are the people who won't stop talking about it.

  • Yes, I like functional programming. But like most other things, it depends on the problem you're trying to solve. If you mosty deal with nails, you'll want to use a hammer. If you mostly deal with screws, you'll want to use a screwdriver. Hammers make lousy screwdrivers and vice-versa.

    Functional languages are great for highly parallelized computation because well-behaved functions don't have side effects, and that eliminates entire classes of race condition and locking issues. Functional languages ar

  • by PhrostyMcByte ( 589271 ) <phrosty@gmail.com> on Sunday April 23, 2017 @11:04PM (#54289949) Homepage

    The best functional programming to me, is the kind being integrated into various primarily procedural languages. I use it daily in C# at work, and find it invaluable in performing complex transformations on data. Python, C#, etc. have the best of both worlds -- the choice to use whatever is best for your situation.

    I'll expand further, maybe to start an interesting conversation because I'm sure someone will disagree: purely- or mostly-functional languages are the original hype-driven languages. A lot of people say they're amazing, but don't actually do anything useful with them. Sure, some are making great apps with them, but they're clearly the exception. At the end of the day most of the people I've talked to who preach about how awesome their favorite functional language is have only gone skin-deep. Their experience is limited to the academic or experimental, and has never gone into the practical.

    The few times I've tried to really master these languages, I've been left with no epiphanies. I've found it extremely useful for some problems, like data processing mentioned above. But for most everything else, it doesn't get me anything useful. On some level it is nice having the flow of immutability -- it "feels" right, like you've discovered something special. The same way adding an extra layer of abstraction on top of something might feel. But when I'd look back on it and ask myself what I gained from having it, there's really very little to be found. It is, mostly, a dogma.

    • Yep. I like functional programming, but it's a tool. But then OO is just a tool as well. It's not suitable for everything, and attempting to apply OO principles to problems that don't really need them is just a waste of everyone's time, just as being forced into a functional pattern when it's not necessary is useless.

      I'm mostly familiar with functional programming in R, where it's an extremely useful part of the language, but you don't have to use it. But once you get used to it, loops end up looking like

  • by jma05 ( 897351 ) on Sunday April 23, 2017 @11:19PM (#54289989)

    All programming paradigms have useful abstractions to offer. Eventually, they will all come together. Object orientation is great, until one overdoes it in design pattern hell. Likewise with functional programming. There are great many ideas in academic programming languages that will be made more accessible and integrated into mainstream programming languages. Functional programming is a dead end only in the sense SmallTalk was a dead end. People may not use SmallTalk much today, but its ideas live on in nearly every language we use today. Functional programming is here to stay. It won't replace imperative and object-oriented programming, but will add to them.

    First and foremost, programming languages are for people, not computers. So if regular programmers who form the bulk of the workforce can't grok them, the languages need to be fixed, not people. Haskell is too hard for most. But it has many wonderful ideas that can be distilled into simpler forms and adopted and integrated elsewhere. Python got list comprehensions from it and perhaps the indentation.

    C# is absorbing some features and Java is doing that less elegantly. Scala is a good balance and has already established itself. But people still find the type system complicated. So there are attempts to bring forth a simpler Scala - Kotlin, Ceylon etc.

    We all agree that things like compact syntax, first order functions, lambdas, streams, type inference etc that functional languages pioneered, belong in every language. We still haven't sorted out how to make more advanced type systems, provability, strict programming without side effects etc more approachable. We should not need to have this much trouble explaining what a monad is or isn't. We'll get there, eventually.

    • So if regular programmers who form the bulk of the workforce can't grok them, the languages need to be fixed, not people.

      I know what you're saying, but there's a real danger here that the industry will find itself caught in a local extremum. An engineer of 1880 could easily have said that if regular engineers who form the bulk of the workforce can't understand this "electricity", then it needs to be fixed to conform to the world of steam.

      The worst thing we can do as an industry is think we know what we're doing [youtube.com]. And in a sense, we're already there.

  • by Jeremi ( 14640 ) on Sunday April 23, 2017 @11:36PM (#54290031) Homepage

    When I was learning about functional programming in college, I got about as far as learning about the avoidance of side effects, at which point I started asking myself, "how would one write a video game in an FP language if you're not supposed to e.g. update the player's on-screen position in response to a keystroke"? The answer I got was to either generate an entire new game-state for each update (which seemed unwieldy), or work around the problem using monads, which admittedly I never really understood. I went back to procedural programming since that looked like the more straightforward way to implement the kinds of programs I wanted to write.

    My question now is, do people ever actually write video games using functional programming? And if so, how would an FP-based arcade-style video game realistically handle things like updating the state of the player and the monsters at 60fps, as the game progresses?

    • You just sketched the worst-case for FP, true. FP is bad for that scenario.

      But it is better at modelling the small state transitions in the objects themselves

    • I would do it by making a function something like, newGameStateScreen() which is a function of the old screen, and the current state (maybe even the old state). That part is fine enough.

      Then I would cheat and optimize it to actually update in place. Conceptually it would still be functional, but every useful functional program ever written mutates state.

      But if you have FP, then you have repeatability. Given a particular game state, combined with a given input, you can know what the next game state wi
    • by jbolden ( 176878 )

      Functional reactive programming came out of the functional community. Assume you had an array of all the inputs the end user entered for a game that already happened. Then the engine can create an array of all the corresponding outputs. That's your engine. Now wrap the construction of those two arrays in a stateful monad (IO).

      This book ( https://www.amazon.com/Haskell... [amazon.com] ) is out of date but it will teach the ideas well. You'll create a video game and a music player.

      In general though, no video games d

    • by Dutch Gun ( 899105 ) on Monday April 24, 2017 @02:06AM (#54290405)

      As a professional videogame programmer, I can assure you that I haven't heard functional programming discussed much at work or among other peers in the industry. Videogames are giant, data-intense state machines, with lots and lots of state to track and manage. My feeling is that it's really not a great fit for functional programming. Traditional object-oriented programming is *heavily* used (C++ is the defacto industry standard language), because that's a reasonable and proven way to encapsulate complex, independently-operating entities into well-behaved packages of data + code.

      It's the same reason that the industry doesn't extensively use unit testing for engines and game code (not broadly at least), which may surprise some programmers in other fields. The reason is simple: many game engine tasks can't be boiled down into simple algorithmic data transformations that can be checked and verified by a simple function. For instance, how would one write a unit test to ensure audio is playing correctly, or a graphic shader is working as intended, or a physics engine "looks" correct in realtime interactions? It's not really practical. Thus, videogames tend to rely on integration tests using QA team members to spot anomalies.

      In short, not every programming paradigm can be effectively applied to every problem. That's not to say you *couldn't* write a game purely in a functional language, of course. I just don't think you'd be working to FP strengths.

  • I tried a websearch the other day on "functional programming considered harmful" and found remarkably few hits. If anyone is so inspired, there's an opportunity there to gain some fame while earning the emnity of the hordes of javascript kids and half of the Computer Science digirati.
    • by dgatwood ( 11270 ) on Monday April 24, 2017 @01:41AM (#54290345) Homepage Journal

      It needs to be done and done well. Very tempting. But alas, just like drug use, there's only so much any sane person can write about the subject, because anyone who knows functional programming well enough to fully explain why it is harmful is probably mentally damaged beyond the point of being able to understand why it is harmful. :-D

      The thing is, functional programming is a good paradigm for students to be exposed to in school. Briefly. It forces you to think about data flow through your program, and forces you to think about your software as a giant state machine and visualize how the states change as your software does work. It is not the only way to teach that concept, but it is a halfway decent way. And once you pick up those concepts, you'll start to understand why singletons are so useful (approximately the polar opposite of functional programming, but often the software equivalent of the data you'd be passing around in a functional world).

      So basically, there's a time and a place for everything, and it's called college. But just like with drugs, if you continue to do significant amounts of functional programming after that, don't be surprised if the rest of us ask what you're smoking. Functional programming as a real-world paradigm tends to be almost invariably a disaster, because it neither fits the way we think about problems (human thinking is almost entirely procedural) nor the way machines do work (computers are inherently procedural). It can provide useful extensions to procedural programming languages that serve specific purposes (e.g. closures), but calling functional programming useful for that reason is akin to calling a diesel-electric freight train a perfect commuter car that saves fuel because a Prius is also hybrid hydrocarbon-electric.

      About the only space where functional programming techniques might really make sense is when working in a massively multithreaded environment, e.g. creating really efficient implementations of certain massively parallelizable functions (such as FFTs). But for the most part, that functional programming is limited to creating components that are then utilized as small (but performance-critical) parts in what is otherwise on the whole still procedural (or OO) software.

      Outside of those very limited scopes, though, the theoretically ivory-tower-pure, zero-side-effect functional programming model is pure garbage. Real world systems don't just have side effects; they are side effects, whether you're talking about storing data on disk, sending it over a wire, drawing it on the screen, reading data from a keyboard, or whatever. The notion of treating all of those "side effects" as some giant state object that mutates as it gets passed around is fundamentally antithetical to real-world use of the data, because state must be stored to be useful. And the entire notion of passing around the complete state of real-world software is so far beyond infeasible that the concept is utterly laughable. Cell phones have a gigabyte of RAM, not a petabyte. There's simply no way to write something like MS Word in a pure functional language, because it would take all the computing resources on the planet to barely run a single instance of it.

      Using functional programming in most real-world environments, then, cannot possibly do anything but cause brain damage, because the whole functional paradigm is wrong for the problem space. It is like cutting the grass on a football field using only a single pair of nail clippers—theoretically possible, but completely infeasible. To that end, although I wouldn't say that functional programming is inherently considered harmful, it should be approached with approximately the same level of skepticism as goto statements, and for approximately the same reason. When used correctly, in a very limited way, it is a powerful tool to have in your toolbox that can seriously improve your software. When overused or misused, it is a black hole that consumes infinite amounts of programmer time while emitting very little.

  • The only time I've tried functional programming was during a class at the Uni. My memory from that class, was that when I finally got a progam through the compiler, it simply worked. No flaws or bugs at all. Of course, a single class doesn't make me qualified to neither promote nor dismiss it. Having said that, I prefer Python for simple PC-based tasks, C (or the non-obscure parts of C++ if the resources permits) for my daily work as embedded designer on ARM Cortex-M and smaller MCU's.
  • My first encounter with both OO and functional programming was Clipper 5.0, the dBase compiler. It incorporated parts of OO and parts of functional programming, lambdas actually, called code blocks. Both have their uses.
  • I've yet to see realistic examples of improvements, at least for domains I work in. Those pushing FP either invent contrived "lab toy" circumstances where FP shines, use vague buzzwords that don't describe any concrete benefit, or merely expose the weakness of a particular language or API design (such as Java's poor OOP model).

    If you want to convince people, show them realistic examples and explain the benefits in concrete and measurable terms. Is that asking too much?

    They may say, "If you use it long enoug

    • A seed planted yields fruit after a few months/years; it needs to be watered and cared for until it grows to that big tree. There are certain things in existence that can't be shown; you have to do it to see it happen to you. If someone hesitates to walk the path because of a lack of proof likely will miss a lot. As Morpheus says, there is a difference between knowing the path and walking the path. It's a about taking a leap of faith; not based on logic.
  • It is helpful in context of walking data model trees in OO languages. It also allows to write stateless code which supports parallelism. It helps with reactive systems including UIs and PLCs. It also sucks in some high performance areas. When people think Optional is a good idea to avoid if then else as code construct and replace it by function calls.

  • by yes-but-no ( 4133651 ) on Monday April 24, 2017 @03:29AM (#54290559)
    In my experience FP style (in python), makes me spend lot more time in the design phase. The emphasis is on data/data-structure more than the code/algorithm/operations [the spotlight of imperative languages]. You start thinking more about how your data gets transformed from input to output. I felt this way of separating data representation from the code/operation lead to more robust code; also much faster implementation phase. FP surely changes the way you think at a higher plane of the problem at hand.
  • I have found two ideas that came from Lisp that are invaluable.

    Minimize side effects in most functions. Any effort to reduce side effects will be repaid tenfold the next time you have to fix a bug or add a feature.

    Keep data objects immutable. This is the key to the easy life if you have to do concurrent programming (and who doesn't these days?).

  • It's just another framework we've had for ages..
    I see it with so many languages, all they do is add functions we already created in the past as standard options. It's really nothing new..
    A problem with a lot of newer frameworks, is that a developer doesn't have any idea anymore as how it actually works underneath, so if something doesn't work they can't figure out why as they don't have the understanding (doesn't mean you have to know all the ins and outs).
    Problem these days is, there are sooooo many framew

  • by DrXym ( 126579 ) on Monday April 24, 2017 @04:54AM (#54290739)
    Anonymous functions / closures / lambdas are fine for small snippets of code, e.g. iterating loops, firing timers, success / fail handlers etc. When you start nesting them or chaining them together with promises or similar constructs, then things can get really hairy.

    Try writing sets of asynchronous Jasmine tests that use promises, lodash iterators, success callbacks and other things of that nature arrays and madness swiftly follows.

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