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Why functional languages?
I began programming with C/C++, VB, and eventually Python - all imperative languages. I took a course about programming languages and learned my first functional language - OCaml. It was terrible.
Syntax and other horrors aside, OCaml took my imperative thought process and threw it out the window. It was frustrating. I insisted that everything that could be done functionally could also be done imperatively. I thought of functional programming as imperative programming without a limb (side effects). In response to my frustration, the only benefit my professor could come up with was an FPL's ability to parallelize side-effect-free functions.
Anyways, enough talk.
What are some advantages that FPLs offer above IPLs?
Is there anything that can easily be done in an FPL that cannot easily be done in an IPL?
Are there any real-world examples of FPLs in use, or do they mostly serve as academic exercises? (When I say real-world, I mean a project that heavily relies on the functional aspect of the language and doesn't cram an FPL into a scenario where it doesn't belong).
Thanks,
Advait
First of all, almost any language in common use today is equivalent in expressive power, be it imperative or functional, so it's natural to think that anything you can do in a functional language you can probably do in an imperative one, because it's probably true.
One of the really nice things about functional languages is that their structure permits the application of Hindley-Milner type inference. This is the type system used in SML, OCaml and a bunch of other functional languages. It genuinely seems to lead to reduced rates of errors and is capable of saving you a lot of time and energy by finding bugs up-front as compile errors.
The automatic parallelisation argument is a bit over-used, especially because the promise simply hasn't eventuated. I have written explicitly parallel code in functional languages and it is nicer, IMHO, than doing something similar in Java or the like.
Anecdotally at least, I wouldn't be the first person to claim that learning a functional language makes you a better imperative programmer! That discomfort you felt in having your "imperative" thought process interrupted when using OCaml is actually a really good process to go through. It makes you question assumptions and stops you from writing code in a particular way just because you have always done it that way.
As for real-world use, you might like to look at the proceedings of the Commercial Users of Functional Programming workshops. There are also some very large projects written in various functional languages, although most of them are probably of limited interest outside fairly small communities. The theorem provers Coq and Isabelle are written in Ocaml and SML, respectively.
Whatever you do, I would persevere. I spent a long time banging my head against ML before things finally clicked. These days I'm not sure I even remember how Java or C work, because I haven't had a need for them in a long time... I just use ML!
When one finally manages to silence his imperativelly (mis)trained mind, FP actually becomes easier and more fun than IP.
FP tends to be safer, less bug prone, due to its declarative nature.
I like to think that parallelising imperative code doubles its complexity (try yourself with a non-trivial parallel app). IMO, FP reduces the gap a lot, thanks to lack of syncronisation in many cases.
Citing Gian, learning FP make you a wiser imperative programmer...
You can read http://www.paulgraham.com/avg.html
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I have read numerous time that learning a language such as Haskell, Lisp or Smalltalk will somehow make you a better programmer while you program in other languages.
Is there more than just anecdotal evidence for that claim?
Or is it just the way people rationalize having spend a lot of time learning a programming language that they will never use?
IMHO, it is all about learning a new programming paradigm. If you know Java and then C#, there's not much gain, once both of them have almost the same "type of programming".
But if you get to learn a functional language or dynamic, for instance, you're forced to think another way, and that will probably help you to program better in your favorite language.
It is something like: "It is so easy doing this in {different language you learned}. There must be a better way to do this in {language you already know}". And then you rethink, and build up a more elegant way to do this in {language you already know}.
I don't have any hard evidence, but I have really appreciated the different way of looking at problems that I have since learning lisp (the same goes for python and c).
The key isn't necessarily learning different languages though, I believe that the key is actually the different viewpoints that you gain by learning different programming styles.
Good examples are functional, imperative, object-oriented, etc. Also, there are common design differences is interpreted vs compiled languages; static vs dynamic typing, etc.
Although most people do a majority of their programming using a single style (most commonly OOP over the past few years), I think that all programmers should know multiple styles so that they are better able to see the shortfalls of their own style.
Can't shed much light on this in terms of programming languages, but it seems very similar to the "why learn a dead language?" argument that surrounds Latin, and much of the reasoning there can be applied here.
Programming is a way of thinking, not writing code in programming language X: that is "coding", not "programming".
By knowing at least something about more than just one programming language - preferably across different paradigms, so imperative/OOP/functional/logical - you train that way of thinking about problems outside the context of the specific details and quirks of language X.
I think this always improves your abilities to be(come) a better programmer tremendously.
A great side-effect of learning new languages is the potential for application in your existing language.
For instance, I'm a Java programmer and I took the time to learn my first functional language (Haskell). I was recently asked to learn Scala for an upcoming project. This is extremely easy since I understand the comcepts of guards, recursion, etc. from Haskell.
Deeply learning language just for learning language has too little benefits. If you have a lot of tasks and you don't know language that ideal for solving it then it is make sense to learn that language. Otherwise it is make sense to spend the time to become expert in languages you already know.
I don't know that there will have been much rigorous study regarding the benefits of multi-programming language exposure on overall programming ability, but I would argue that the studies regarding why learning a foreign human language (which you may never use in practice) is beneficial would in general hold equally well for studying foreign programming languages. The benefits ascribed often include improved cognitive abilities as well as improved understanding of one's native language.
here's some links to studies
anecdotally, I complained a great deal about taking COBOL, and have never really used it but was able to apply things I learned in that class at my first job.
If you give any credence to the Pragmatic Programming guys, consider their advice from page 14 of their first book:
Learn at least one new language every year. Different languages
solve the same problems in different ways. By learning several
different approaches, you can help broaden your thinking and avoid
getting stuck in a rut.
Some examples that come to mind:
Knowing C and having to deal with memory management and do-it-yourself data structures can help you understand performance issues when programming in a higher level language where those details are hidden from you.
Conversely, learning an OO language can affect your C programming - with, for example, the concept of Polymorphism prompting you to use function pointers in ways you might not have otherwise.
Learning a language where functions are first class objects that can be passed around can make you think of similar techniques in other languages, even if, in those other languages, you have to make the functions methods in objects that get passed around.
Learning about the way Erlang handles concurrency can make you rethink how much shared state you use between threads in other languages.
Any language that has a built-in feature you find useful can prompt you to implement your own version of that feature in another language that doesn't have it, and thus allow you to solve problems in ways you might not have thought of if you hadn't been exposed to the feature in the language that has it built-in.
Learning about Interfaces in Java can make you think about the benefits of precisely specifying your (small "i") interfaces in other languages that don't have them as a formal construct in a type system.
No doubt there are others.
Learning a language is not a binary event. If you are a decent programmer, you should be able to trust your own instincts as to whether a language offers you a new take on your craft.
Virtually every language worth considering these days can be downloaded and test-driven in a couple of minutes. So do it -- pick one and try it out.
There are a limited number of cases where this "laissez-faire" approach falls short. If you're a complete beginner, of course it doesn't work. When I first learned C, I had to have it beaten into me, but it did turn out to be worth it because it made me understand pointers, memory reference and dynamic allocation in a way I hadn't previously.
But if you know that much already, just poke around and look for a language that makes your lightbulb go on.
Different languages have different ways of implementing the same ideas. By learning new languages, you get a different perspective on how things can be accomplished, and can then use that knowledge to approach how you program in your current environment. Think about object oriented and functional programming. OO Programmers can learn a lot about parrellization from languages like C.
Learning a language, especially one that practices a new paradigm, is very beneficial for every programmer. For example learning Scheme will help someone understand functional programming. The programmer can later practice what he/she learned with other languages like C#. She can think of new ways of doing things.
Also, as languages evolve, it's high likely that the language you use will adopt some features of other languages. Having taught myself Ruby, I was able to grasp the changes in C# 3.0 much easier.
I think learning languages will always benefit you even if you don't use them again. I started playing with Ioke as an attempt to learn something experimental and because of it my JavaScript has improved because certain ideas have been cemented.
learning a new language will possibly give you new insights that you will try translate to your main language.
I don't think there will be any hard evidence--I think this is more of an intuitive thing. Learning a totally different language will help you look at things totally different. Or maybe it won't. In any case, what's the harm in learning something?
It's entirely subjective, but way back when, after taking an undergraduate course in Haskell, I did notice that my programming style in C became more 'Haskell-like' for a while; I used a lot of simple, recursive functions. I also noticed that this programming style seemed to yield some of the same benefits programming in Haskell had; bugs were fewer, code was easier to understand (albeit slower).
So, while learning another programming language may not make everyone a better programmer, it definitely was a learning experience for me, personally.
What are the benefits of learning mathematics or physics that you won't use, or the benefits of studying philosophy or dead tongues?
It's the intellectual achievement and the enlightenment what matters, you will be a wiser person with any new thing that you learn, no matter if they are programming languages, literature, role playing games... of course if it's related to your working field, then you'll actually find a use, sooner or later :-)
I spent some time studying clojure even though I knew I wouldn't use it in the near-term (mostly because I can't really deploy on the JVM).
It has concepts that aren't supported by the languages I use (C#/C/C++/Python/Perl) and I wanted to know what I was missing and also if it would be worth looking into libraries that purport to add these features.
Specifically, I'm very interested in understanding Lisp-style macros and the direct concurrency support. I also spent some time reading the implementation, specifically the datastructures, which was very educational -- good to see a quality implementation of persistent datastructures to learn how they work (and give you immutability without sacrificing much performance).
Bryond what has already been said, I really like new languages just because it can bring new interest to programming. You learn different ways to approach problems and the strengths/weaknesses of certain languages. It is something new to learn and any good programmer should be striving to always be learning new things. It mixes up your daily routine of possibly programming in the same language for years.
I also like what everyone has said about programming perspective.
Some good points have been made.
I would add that learning languages you won't use in production work can be of value
To better appreciate and absorb the arguments and methods in texts and papers that will improve programming ability in languages I do use for production work (e.g. MIX/MMIX for Knuth's Art of Computer Programming; RATFOR for Kernighan and Plauger's Software Tools; I still use some ALGOL-based syntax for some pseudocode although I never wrote runnable code in ALGOL outside University)
To be able to check or prototype programs that will be written in a different language (e.g. some routines for numerical computing in C can be quickly checked or scaled using languages that have appropriate functionality built in such as Fortran, Python or Haskell)
Learning a new language can give insight as to how it could be used to more easily solve problems that were put to one side because of time or complexity constraints.
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What is the real benefit of creating a new programming language? It is highly unlikely that you are going to actually use it.
In short, how will the process of creating a new language make you a better programmer?
You will understand the decisions behind language design and garner a better overall understanding of the compromises made between readability, performance, and reliability.
Your familiarity with concepts such as recursion, closures, garbage collection, reference management, typing, data structures and how these things actually work will increase. Most programmers will utilize resources and language features better.
Similar to the way we learn new ways to code solutions when we use other languages, when we write our own languages, we explore new ways to create solutions. See Metaprogramming. Contrary to the what the question suggests, Domain Specific Languages are used in many environments.
If you're writing a compiler, you'll learn more about how computers work than you ever did before. (Depending on your goal, perhaps more than you intended to learn)
When I wrote my own sort routines in school, even re-implementations of good ones, it really drove home some of the weaknesses of some of the algorithms.
In short, there's an order of magnitude of difference in a programmer who knows how to use tools, and a programmer who knows how to make tools.
I can speak from experience here ...
Fun, Domain specific problem solving, Complexity in context
I love creating new languages for fun, and for tackling domain specific problems. A very simple example might be Wikipedia markup or something as complex as Erlang which specializes in concurrent processing.
Many general purpose languages are similar, because they are general purpose. Sometimes you need a more accurate abstraction of the mechanics of the problem you are solving. Another example would be the M4 macro language.
Remember a language is not magic, it is just a collection of defined grammatical structures with implied semantics. SQL is a good example of a language for a purpose, with that purpose defined in it's syntax and semantics.
Learning how languages work, what makes a language parsable, what makes semantics sensible and the implementation of this, I think can make you a better programmer.
compilers embody alot of theory that underpins computer science:
Translation, abstraction, interpretation, data structures, state .... the list goes on. Learning these things will make you understand the implications of your program and what goes on under the hood. You can of course learn things independently but compilers are a great context to learn complex topics such as DFA/NDFA automata, stack-based parsers, abstract syntax trees ....
compilers are beautiful machines I think :)
Multiple reasons:
bragging rights
economic incentives
extreme boredom
dissatisfaction with the hundreds of existing languages
untreated insanity
desire to implement language that facilitates new design concepts (like languages that make design patterns more straightforward to incorporate)
other reasons, perhaps
I think Jeff Attwood answers this well in this Coding Horror post -- though he's talking about a more general issue (why create any new library, framework, etc, when other artifacts in the same design space already exist), I suspect that exactly said broader viewpoint gives him a different and interesting perspective.
I will add that if you write a semantics, so that your language is an actual language and not merely what happens to be accepted by some particular implementation, you will learn an enormous amount about how to describe computational behaviors precisely:
You will learn what kinds of behaviors are and are not easy to describe—and prove correct.
You will learn how to trade off different kinds of formalisms for describing different kinds of features.
You will ultimately be a better programmer because the formalism and proof techniques you will learn will apply to all kinds of problems: locking techniques, safety properties in kernels, lock-free data structures, network protocols, and information security, to name just a few. All these areas are amenable to the same kind of formal treatment that is given to a programming language.
To pick just one example, if you give your language a static type system and you then prove that a well-type program is guaranteed to be memory-safe, you will learn just as much (on a different dimension) as you will by writing an interpreter or compiler.
EDIT: If you want to learn this stuff I think the easiest starting point is Benjamin Pierce's series of two books on Types and Programming Languages. There is also a graduate textbook by Glynn Winskel which is a little harder but more oriented toward semantics and proof techniques.
Creating Domain Specific Languages is very valuable. Instead of thinking only about general purpose languages, consider creating so-called "little languages" that clearly express abstractions in your project.
For example, in a recent project I decided to use a Command Pattern to drive a Service Layer. I found some repetition in my command code, so I wrote a little compiler that accepts a simple language that expresses commands and emits command implementations in the "underlying" language.
For the same reason that taking a Compiler Construction course at university will benefit you even if you never write a single compiler in your whole life. It's a look under the hood, if you may.
In addition to what altCognito said, which is a theoretical/academic perspective, some highly specialized languages are created to solve specific problems efficiently when existing "general-purpose" languages are either extremely inefficient for your task or there just isn't an easy-to-use existing alternative.
Granted, that such cases tend to be rare and if your first instinct on encountering a problem is "I need a new language for this.", then it is most likely you're missing something. There needs to be a fairly substantial gap in "available" tech and and your needs to warrant such an undertaking.
I think there are really two conceptually different answers to this. First, you gain an understanding of how compilers transform your code into executable code. This can help you make better decisions about how to structure your code to optimize (or allow it to be optimized) better. If, for instance, you knew that a certain construct would prohibit the compiler from inlining a code block or unrolling a loop, then you could avoid that if performance became a real concern.
Second, all current languages were invented (or derived) at some point in history. For each one of these, the likelihood that it would actually be used was potentially small, yet here they are. They all found their reason for being in the fact that someone wanted to do something that wasn't possible or easy to do in an existing language and decided to do something about it. Laziness (or the desire to let the computer do the work for you) is the mother of invention.
Just for fun... and then you'll realize that you cannot make anything better than all the languages that you thought they sucked xD (so you stop complaining about them).
how will the process of creating a new language make you a better programmer?
You're right, you may or may not use the language, but at the least the experience you will gain from doing it will benefit you to understand the implementation of programming languages and of certain things that you will be able to apply to future computation problems that you run into.
Writing a compiler or interpreter requires a very firm understanding in computer science theory. And if you're compiling to machine code instead of to another language, it requires a firm understanding in hardware design as well.
In addition to that, knowing how to design a compiler means you will have a better understanding of languages in general, and the languages you work with specifically. You will have a better appreciation for syntax and trade-offs the language designers took when they wrote their specification.
It's not that writing compilers makes you a better programmer. It's the deep understanding of language theory and compiler design that makes you better.
Mostly you do this for fun or to broaden your comprehension of a subject.
I disagree that creating new language influences performance - performance of what? IMHO execution speed should not depend on the language constructs but what the language is translated to - which is something different: like creating a syntax for a language and writting a compiler/virtual machine for it.
Because a talking frog is pretty neat.
I want a managed language that permits tinkering with its internals as standard practice. Kind of like Ruby's duck punching on a wider scale.
I should, as the client of a library, be able to swap out library functions that don't do what I want.
That's what drives me crazy with .NET. There are bugs in the framework Microsoft will not fix and thanks to GAC signing I cannot. And even if it were not for GAC signing, hotpatching a global library is a bad idea (might break some other application).
I for one don't care about how compilers work, don't care about learning new languages, and don't care about using scripting languages like perl and javascript. I'm much more interested in the ways big programs are constructed (or should be constructed). There are still no good solutions for making LARGE software as easy to use as prototyped code. Programming languages are not helping with that. They solve trivial problems like sorting and memory deallocation, and leave you struggling alone with problems that really matter (that keep you or your firm from losing money).
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These days I'm getting seriously into functional programming.
While I'm really excited about Haskell and the possibilities it seems to offer, I can also see now that it is going to take me a while to learn. In an SO question on How to learn Haskell an answer states that it'll take months if not years to actually "master" it.
Now, I know C, PHP, some object oriented stuff, etc. And having been told that Haskell isn't much used out there in "the real world", will I be better off improving my skills in the regular languages I know? Is Haskell worth the struggle?
In this question on Why people think functional programming will catch on the conclusion seems to be that functional programming will "catch on". But surely procedural programming will stay on top, right?
EDIT: keparo nicely clarifies my question to: As opposed to procedural languages, will it be valuable for me to study Haskell and functional programming paradigms?
Haskell isn't as hard as people like to make out to learn. Haskell opens up a new world that you never knew existed for you. It's as valuable to learn as any other language. You might not find a job requiring you to do Haskell programming, but does that really mean a language isn't valuable?
Haskell will teach you a lot of new stuff, and it will show you how to program even better in the languages you /do/ work with. You can do your own personal projects in your spare time with it.
Haskell isn't really used much in the "real world" if you define "real world" as "cash generator". So if that is your objective, then you might have to rethink objectives :p
Also, I don't really like that part of chosen "how to learn haskell" answer. It takes months to years to master any language, not just Haskell. Depending on how you define "master". I can use Haskell to a pretty good degree of efficiency and I've only been learning it for a month, and I've been taking it slow even.
If nothing else, the change in mindset that learning Haskell provides will help you when you have to go back to using those procedural languages that still are used in the workplace.
The functional paradigm is beginning to make it's way into various mainstream applications and languages - Even C++ is going to be adding a (crippled) lambda in C++0x.
You may also want to look at some of the hybrid languages like Scala or OCaml. Scala is being used at Twitter, and OCaml is being used at Jane's Street in a financial trading platform.
I learned Haskell because it was by far the best functional language that I tried out of Scala, Clojure, OCaml and Scheme but I didn't seriously expect to use it for work.
As it turns out, it is perfect for those sorts of odd jobs that are too small for a team and would be just too time consuming in Java. So far, I've used it for ad-hoc data migrations i.e. mangling CSV exports into another format, batch conversions of XML (HXT is more concise and more powerful than XSLT), screen-scraping off the internet and software project estimating including modelling risk using the probability monad and producing optimum gantt charts using backtracking. This is all real work that needed doing, that I wouldn't have even bothered to try and do in Java as it would be a multi-day undertaking.
I now use it instead of Excel for anything vaguely mathematical as it is little more effort to create a list of values in haskell source in a text editor than it is to type them into Excel. Once in haskell, I can then do all sorts of magic like backtracking, probability distributions etc. that Excel can't do. If I need a graph then I spit the values out as CSV (2 lines of code) and load them into Excel.
The only downside is that it does take several months to get proficient, but worth the effort IMHO.
You probably shouldn't expect to use Haskell anywhere nearly as often as a C family language in professional settings. If the question is whether it will be valuable for you to study Haskell and functional programming paradigms, the answer is yes. You can apply your enriched understanding of programming to all of your work.
As opposed to procedural languages, will it be valuable for me to study Haskell and functional programming paradigms?
If having an expanded skill set is valuable, then: yes.
One advantage you might pick up: parallel and concurrent programming. Procedural languages of the past tend to have no clear notion of side effects, as a result writing parallel programs in them is difficult to do correctly. Functional languages (in particular, ones that limit side effects like Haskell) have a lot more to say about productive parallel programming.
Having that skill up your sleeve can't hurt.
As opposed to procedural languages, will it be valuable for me to study Haskell and functional programming paradigms?
Not unless you want to be miserable. Luke Plant says, in Why learning Haskell/Python makes you a worse programmer:
So, learning Python and Haskell has demoralised me and encouraged
me to write code that is bizarre and difficult to understand...
(This is not entirely a joke.)
I can see that functional programming can be a plus in a production environment if it's very easy to use by non functional code. MS could see that too when they came up with F# I guess.
Since they both compile to IL, you can handle problems that ask for a functional approach functional and use those solutions very easily in your procedural code.
In that way functional code can easily find its way in a production environment a bit at a time
Therefore, and since the userbase of MS is that big, my guess is that if F# will not catch on in the very near future, that Haskell won't either.
I think it's worth the struggle. It will help you to understand how problems are solved and not only how a computer works.
Maybe one particular problem is Haskell itself - As a purely functional language, it's kinda "hardcore" which may on the other hand even complicate things.
Functional programming instead may be extremely useful in a very pragmatic manner - Many OO/imperative languages have now included functional elements for this reason (Linq, anonymous functions, readonly values, function pointers/delegates, type-inference): You can concentrate on what should be done which allows you to express more in less code (that is even less error-prone).
Non-purely functional languages (standard functional languages) like Scala or F# can be integrated easily into existing Java or .NET-projects, so you can combine the benefits of both paradigms where they are needed. For typical advantages of functional languages, see this thread. Just think of extremely powerful parsing (Monadic parser combinators / Parsec) or concurrent programming that is possible with functional languages and you'll see how useful they are.
Broadening your horizons helps you be a better programmer no matter what language you happen to be using at the moment. You'll never look at programming the same way after you've written Lisp macros, for instance. After you begin to think in Haskell terms, you'll find yourself composing functions and wishing for closures in less advanced languages.
Judging from goodies in C# such as lambdas, type inference, closures, and so on, learning Haskell will give you a leg up on tomorrow's cutting edge in mainstream languages.
Some people enjoy programming in Haskell. If you can choose your environment, and enjoyment is a consideration, then maybe you should hop in.
Many programmers are not in position to choose their tools and enjoyment is not a factor for their choices. Many of them get to use C/Java/etc at their workplace for the "core project source", but then also choose or need to use Python for "scripts" such as build-scripts with SCons, other scripts that generate Java/etc code, testing systems, proofs-of-concepts, etc.. And in other places Python is also used in the "core project".
In 8 years, it will be Haskell, not Python, which will be "coming to you". But you can come to it sooner.
You can combine the use of functional programming and be pragmatic about the language.
All modern scripting languages s.a. JavaScript or Lua allow use of the functional paradigm.
The functional concept is coming on strong. Note the flurry of activity and interest around Ruby. I've also noticed a bit more interest in JavaScript beyond a mere browser scripting language lately. You can get ahead of the game by diving in now, though the time invested might not pay off this year or next.
It depends on your general game plan. Are you into programming as an end in itself or as a means to an end? If it's the former, go nuts with Haskell. If the latter, stick with mainstream, "employable" languages. Wait for Haskell to take off and then pounce.
Why procedural and not Object Oriented, not seen procedural being used for many years apart from C.
Commercially speaking. I would go with Java or C#. Doesn't really matter which they both pay well and the skills are interchangeable with other like minded languages such as python, Ruby and JavaScript.
Haskell is worth the time and effort, although it is very academic, some banks use it, although many in Europe and the UK are moving the code base over to F#.
I don't think FOP will be moving at great speeds commercially speaking. But the techniques are definitely making an appearance in the main stay languages. Especially with Multi-Core chip designs and making code run parallel on them.
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I see a lot of talk on here about functional languages and stuff. Why would you use one over a "traditional" language? What do they do better? What are they worse at? What's the ideal functional programming application?
Functional languages use a different paradigm than imperative and object-oriented languages. They use side-effect-free functions as a basic building block in the language. This enables lots of things and makes a lot of things more difficult (or in most cases different from what people are used to).
One of the biggest advantages with functional programming is that the order of execution of side-effect-free functions is not important. For example, in Erlang this is used to enable concurrency in a very transparent way.
And because functions in functional languages behave very similar to mathematical functions it's easy to translate those into functional languages. In some cases, this can make code more readable.
Traditionally, one of the big disadvantages of functional programming was also the lack of side effects. It's very difficult to write useful software without I/O, but I/O is hard to implement without side effects in functions. So most people never got more out of functional programming than calculating a single output from a single input. In modern mixed-paradigm languages like F# or Scala this is easier.
Lots of modern languages have elements from functional programming languages. C# 3.0 has a lot functional programming features and you can do functional programming in Python too. I think the reasons for the popularity of functional programming is mostly because of two reasons: Concurrency is getting to be a real problem in normal programming, because we're getting more and more multiprocessor computers; and the languages are getting more accessible.
I don't think that there's any question about the functional approach to programming "catching on", because it's been in use (as a style of programming) for about 40 years. Whenever an OO programmer writes clean code that favors immutable objects, that code is borrowing functional concepts.
However, languages that enforce a functional style are getting lots of virtual ink these days, and whether those languages will become dominant in the future is an open question. My own suspicion is that hybrid, multi-paradigm languages such as Scala or OCaml
will likely dominate over "purist" functional languages in the same way that pure OO language (Smalltalk, Beta, etc.) have influenced mainstream programming but haven't ended up as the most widely-used notations.
Finally, I can't resist pointing out that your comments re FP are highly parallel to the remarks I heard from procedural programmers not that many years ago:
The (mythical, IMHO) "average" programmer doesn't understand it.
It's not widely taught.
Any program you can write with it can be written another way with current techniques.
Just as graphical user interfaces and "code as a model of the business" were concepts that helped OO become more widely appreciated, I believe that increased use of immutability and simpler (massive) parallelism will help more programmers see the benefits that the functional approach offers. But as much as we've learned in the past 50 or so years that make up the entire history of digital computer programming, I think we still have much to learn. Twenty years from now, programmers will look back in amazement at the primitive nature of the tools we're currently using, including the now-popular OO and FP languages.
The main plus for me is its inherent parallelism, especially as we are now moving away from higher CPU clock frequency and towards more and more cores.
I don't think it will become the next programming paradigm and completely replace OO type methods, but I do think we will get to the point that we need to either write some of our code in a functional language, or our general purpose languages will grow to include more functional constructs.
Even if you never work in a functional language professionally, understanding functional programming will make you a better developer. It will give you a new perspective on your code and programming in general.
I say there's no reason to not learn it.
I think the languages that do a good job of mixing functional and imperative style are the most interesting and are the most likely to succeed.
I'm always skeptical about the Next Big Thing. Lots of times the Next Big Thing is pure accident of history, being there in the right place at the right time no matter whether the technology is good or not. Examples: C++, Tcl/Tk, Perl. All flawed technologies, all wildly successful because they were perceived either to solve the problems of the day or to be nearly identical to entrenched standards, or both. Functional programming may indeed be great, but that doesn't mean it will be adopted.
But I can tell you why people are excited about functional programming: many, many programmers have had a kind of "conversion experience" in which they discover that using a functional language makes them twice as productive (or maybe ten times as productive) while producing code that is more resilient to change and has fewer bugs. These people think of functional programming as a secret weapon; a good example of this mindset is Paul Graham's Beating the Averages. Oh, and his application? E-commerce web apps.
Since early 2006 there has also been some buzz about functional programming and parallelism. Since people like Simon Peyton Jones have been worrying about parallelism off and on since at least 1984, I'm not holding my breath until functional languages solve the multicore problem. But it does explain some of the additional buzz right about now.
In general, American universities are doing a poor job teaching functional programming. There's a strong core of support for teaching intro programming using Scheme, and Haskell also enjoys some support there, but there's very little in the way of teaching advanced technique for functional programmer. I've taught such a course at Harvard and will do so again this spring at Tufts. Benjamin Pierce has taught such a course at Penn. I don't know if Paul Hudak has done anything at Yale. The European universities are doing a much better job; for example, functional programming is emphasized in important places in Denmark, the Netherlands, Sweden, and the UK. I have less of a sense of what's happening in Australasia.
I don't see anyone mentioning the elephant in the room here, so I think it's up to me :)
JavaScript is a functional language. As more and more people do more advanced things with JS, especially leveraging the finer points of jQuery, Dojo, and other frameworks, FP will be introduced by the web-developer's back-door.
In conjunction with closures, FP makes JS code really light, yet still readable.
Cheers,
PS
Most applications are simple enough to be solved in normal OO ways
OO ways have not always been "normal." This decade's standard was last decade's marginalized concept.
Functional programming is math. Paul Graham on Lisp (replace Lisp by functional programming):
So the short explanation of why this
1950s language is not obsolete is that
it was not technology but math, and
math doesn’t get stale. The right
thing to compare Lisp to is not 1950s
hardware, but, say, the Quicksort
algorithm, which was discovered in
1960 and is still the fastest
general-purpose sort.
I bet you didn't know you were functional programming when you used:
Excel formulas
Quartz Composer
JavaScript
Logo (Turtle graphics)
LINQ
SQL
Underscore.js (or Lodash),
D3
The average corporate programmer, e.g.
most of the people I work with, will
not understand it and most work
environments will not let you program
in it
That one is just a matter of time though. Your average corporate programmer learns whatever the current Big Thing is. 15 years ago, they didn't understand OOP.
If functional programming catches on, your "average corporate programmers" will follow.
It's not really taught at universities
(or is it nowadays?)
It varies a lot. At my university, SML is the very first language students are introduced to.
I believe MIT teaches Lisp as a first-year course. These two examples may not be representative, of course, but I believe most universities at the very least offer some optional courses on functional programming, even if they don't make it a mandatory part of the curriculum.
Most applications are simple enough to
be solved in normal OO ways
It's not really a matter of "simple enough" though. Would a solution be simpler (or more readable, robust, elegant, performant) in functional programming? Many things are "simple enough to be solved in Java", but it still requires a godawful amount of code.
In any case, keep in mind that functional programming proponents have claimed that it was the Next Big Thing for several decades now. Perhaps they're right, but keep in mind that they weren't when they made the same claim 5, 10 or 15 years ago.
One thing that definitely counts in their favor, though, is that recently, C# has taken a sharp turn towards functional programming, to the extent that it's practically turning a generation of programmers into functional programming programmers, without them even noticing. That might just pave the way for the functional programming "revolution". Maybe. ;)
Man cannot understand the perfection and imperfections of his chosen art if he cannot see the value in other arts. Following rules only permits development up to a point in technique and then the student and artist has to learn more and seek further. It makes sense to study other arts as well as those of strategy.
Who has not learned something more about themselves by watching the activities of others? To learn the sword study the guitar. To learn the fist study commerce. To just study the sword will make you narrow-minded and will not permit you to grow outward.
-- Miyamoto Musashi, "A Book of Five Rings"
One key feature in a functional language is the concept of first-class functions. The idea is that you can pass functions as parameters to other functions and return them as values.
Functional programming involves writing code that does not change state. The primary reason for doing so is so that successive calls to a function will yield the same result. You can write functional code in any language that supports first-class functions, but there are some languages, like Haskell, which do not allow you to change state. In fact, you're not supposed to make any side effects (like printing out text) at all - which sounds like it could be completely useless.
Haskell instead employs a different approach to I/O: monads. These are objects that contain the desired I/O operation to be executed by your interpreter's toplevel. At any other level they are simply objects in the system.
What advantages does functional programming provide? Functional programming allows coding with fewer potentials for bugs because each component is completely isolated. Also, using recursion and first-class functions allows for simple proofs of correctness which typically mirror the structure of the code.
I don't think most realistic people think that functional programming will catch on (becomes the main paradigm like OO). After all, most business problems are not pretty math problems but hairy imperative rules to move data around and display them in various ways, which means it's not a good fit for pure functional programming paradigm (the learning curve of monad far exceeds OO.)
OTOH, functional programming is what makes programming fun. It makes you appreciate the inherent, timeless beauty of succinct expressions of the underlying math of the universe. People say that learning functional programming will make you a better programmer. This is of course highly subjective. I personally don't think that's completely true either.
It makes you a better sentient being.
I'd point out that everything you've said about functional languages, most people were saying about object-oriented langauges about 20 years ago. Back then it was very common to hear about OO:
* The average corporate programmer, e.g. most of the people I work with, will not understand it and most work environments will not let you program in it
* It's not really taught at universities (or is it nowadays?)
* Most applications are simple enough to be solved in normal IMPERATIVE ways
Change has to come from somewhere. A meaningful and important change will make itself happen regardless of whether people trained in earlier technologies take the opinion that change isn't necessary. Do you think the change to OO was good despite all the people that were against it at the time?
I must be dense, but I still don't get it. Are there any actual examples of small application's written in a functional language like F# where you can look at the source code and see how and why it was better to use such an approach than, say, C#?
F# could catch on because Microsoft is pushing it.
Pro:
F# is going to be part of next version of Visual Studio
Microsoft is building community for some time now - evangelists, books, consultants that work with high profile customers, significant exposure at MS conferences.
F# is first class .NET language and it's the first functional language that comes with really big foundation (not that I say that Lisp, Haskell, Erlang, Scala, OCaml do not have lots of libraries, they are just not as complete as .NET is)
Strong support for parallelism
Contra:
F# is very hard to start even if you are good with C# and .NET - at least for me :(
it will probably be hard to find good F# developers
So, I give 50:50 chance to F# to become important. Other functional languages are not going to make it in near future.
I think one reason is that some people feel that the most important part of whether a language will be accepted is how good the language is. Unfortunately, things are rarely so simple. For example, I would argue that the biggest factor behind Python's acceptance isn't the language itself (although that is pretty important). The biggest reason why Python is so popular is its huge standard library and the even bigger community of third-party libraries.
Languages like Clojure or F# may be the exception to the rule on this considering that they're built upon the JVM/CLR. As a result, I don't have an answer for them.
It seems to me that those people who never learned Lisp or Scheme as an undergraduate are now discovering it. As with a lot of things in this field there is a tendency to hype and create high expectations...
It will pass.
Functional programming is great. However, it will not take over the world. C, C++, Java, C#, etc will still be around.
What will come of this I think is more cross-language ability - for example implementing things in a functional language and then giving access to that stuff in other languages.
When reading "The Next Mainstream Programming Language: A Game Developer’s Perspective" by Tim Sweeney, Epic Games, my first thought was - I got to learn Haskell.
PPT
Google's HTML Version
Most applications can be solved in [insert your favorite language, paradigm, etc. here].
Although, this is true, different tools can be used to solve different problems. Functional just allows another high (higher?) level abstraction that allows to do our jobs more effectively when used correctly.
Things have been moving in a functional direction for a while. The two cool new kids of the past few years, Ruby and Python, are both radically closer to functional languages than what came before them — so much so that some Lispers have started supporting one or the other as "close enough."
And with the massively parallel hardware putting evolutionary pressure on everyone — and functional languages in the best place to deal with the changes — it's not as far a leap as it once was to think that Haskell or F# will be the next big thing.
It's catching on because it's the best tool around for controlling complexity.
See:
- slides 109-116 of Simon Peyton-Jones talk "A Taste of Haskell"
- "The Next Mainstream Programming Language: A Game Developer's Perspective" by Tim Sweeney
Check out Why Functional Programming Matters.
Have you been following the evolution of programming languages lately? Every new release of all mainstream programming languages seems to borrow more and more features from functional programming.
Closures, anonymous functions, passing and returning functions as values used to be exotic features known only to Lisp and ML hackers. But gradually, C#, Delphi, Python, Perl, JavaScript, have added support for closures. It's not possible for any up-and-coming language to be taken seriously without closures.
Several languages, notably Python, C#, and Ruby have native support for list comprehensions and list generators.
pioneered generic programming in 1973, but support for generics ("parametric polymorphism") has only become an industry standard in the last 5 years or so. If I remember correctly, Fortran supported generics in 2003, followed by Java 2004, C# in 2005, Delphi in 2008. (I know C++ has supported templates since 1979, but 90% of discussions on C++'s STL start with "here there be demons".)
What makes these features appealing to programmers? It should be plainly obvious: it helps programmers write shorter code. All languages in the future are going to support—at a minimum—closures if they want to stay competitive. In this respect, functional programming is already in the mainstream.
Most applications are simple enough to
be solved in normal OO ways
Who says can't use functional programming for simple things too? Not every functional program needs to be a compiler, theorem prover, or massively parallel telecommunications switch. I regularly use F# for ad hoc throwaway scripts in addition to my more complicated projects.
Wow - this is an interesting discussion. My own thoughts on this:
FP makes some tasks relatively simple (compared to none-FP languages).
None-FP languages are already starting to take ideas from FP, so I suspect that this trend will continue and we will see more of a merge which should help people make the leap to FP easier.
I don't know whether it will catch on or not, but from my investigations, a functional language is almost certainly worth learning, and will make you a better programmer. Just understanding referential transparency makes a lot of design decisions so much easier- and the resulting programs much easier to reason about. Basically, if you run into a problem, then it tends to only be a problem with the output of a single function, rather than a problem with an inconsistant state, which could have been caused by any of the hundreds of classes/methods/functions in an imparative language with side effects.
The stateless nature of FP maps more naturally to the stateless nature of the web, and thus functional languages lend themselves more easily to more elegant, RESTFUL webapps. Contrast with JAVA and .NET frameworks that need to resort to horribly ugly HACKS like VIEWSTATE and SESSION keys to maintain application state, and maintain the (occasionally quite leaky) abstraction of a stateful imperative language, on an essentially stateless functional platform like the web.
And also, the more stateless your application, the more easily it can lend itself to parallel processing. Terribly important for the web, if your website happens to get popular. It's not always straightforward to just add more hardware to a site to get better performance.
My view is that it will catch on now that Microsoft have pushed it much further into the mainstream. For me it's attractive because of what it can do for us, because it's a new challenge and because of the job opportunities it resents for the future.
Once mastered it will be another tool to further help make us more productive as programmers.
A point missed in the discussion is that the best type systems are found in contemporary FP languages. What's more, compilers can infer all (or at least most) types automatically.
It is interesting that one spends half the time writing type names when programming Java, yet Java is by far not type safe. While you may never write types in a Haskell programm (except as a kind of compiler checked documentation) and the code is 100% type safe.
I agree with the first point, but times change. Corporations will respond, even if they're late adopters, if they see that there's an advantage to be had. Life is dynamic.
They were teaching Haskell and ML at Stanford in the late 1990s. I'm sure that places like Carnegie Mellon, MIT, Stanford, and other good schools are presenting it to students.
I agree that most "expose relational databases on the web" applications will continue in that vein for a long time. Java EE, .NET, Ruby on Rails, and PHP have evolved some pretty good solutions to that problem.
You've hit on something important: It might be the problem that can't be solved easily by other means that will boost functional programming. What would that be?
Will massive multicore hardware and cloud computing push them along?
Because functional programming has significant benefits in terms of productivity, reliability and maintainability. Many-core may be a killer application that finally gets big corporations to switch over despite large volumes of legacy code. Furthermore, even big commercial languages like C# are taking on a distinct functional flavour as a result of many-core concerns. Side effects simply don't fit well with concurrency and parallelism.
I do not agree that "normal" programmers won't understand it. They will, just like they eventually understood OOP (which is just as mysterious and weird, if not more so).
Also, most universities do teach functional programming , many even teach it as the first programming course.
In addition to the other answers, casting the solution in pure functional terms forces one to understand the problem better. Conversely, thinking in a functional style will develop better* problem solving skills.
*Either because the functional paradigm is better or because it will afford an additional angle of attack.