10 ms·

Functional Programming is Dead, Long Live Expression-Oriented Programming

45 points by Rickasaurus 14y ago

sohn10 14y ago
No.
- Rickasaurus 14y ago
  Care to elaborate?
smeg 14y ago
Functional programming was alive? Who knew.
monkeyfacebag 14y ago
I will freely admit to thinking I knew something about functional programming after learning about lambdas, map, filter and reduce in Python (and lamenting the language's lack of tail call optimization). Three days with Haskell set me straight.
- Ixiaus 14y ago
  Haskell, Scheme (a LISP), Erlang, Clojure will all set you straight. What's great is, once you grok one; the others are much easier to get a handle on.
cantankerous 14y ago
I don't get the jump between talking about how "functional" doesn't evoke purity, yet "expression-oriented", does. To be fair, most (probably all) functional languages aren't fully pure. Haskell is probably more pure than most of them, but eventually you have to get things done and dive into the sin bin. The term "functional" really evokes "first class" invokable function symbols that can be passed around in a higher-order kind of way. Everything else is secondary.
- Rickasaurus 14y ago
  Expression-Oriented evokes purity in that expressions have external facing properties which can be understood and even kept in the type system. If you use global mutation and you don't keep track of it in the type system you can't say much about those properties anymore. You can however use mutation locally and maintain your referential transparency which is a nice way to get around the limits of some not-so-functional-friendly algorithms. I'm planning on writing about that next time around because my tracking shows barely anyone gets to the end of an article beyond a certain length.
kenbot 14y ago
Making things like if/else/switch statements true expressions is a great feature, but I'm not sure it deserves a new foo-oriented programming buzzword.
- Rickasaurus 14y ago
  The reason I suggested it is because functional has been so badly perverted. We need a term that evokes the actual spirit/philosophy of the language, not just the heritage.
- Jebus 14y ago
  True, this is just a feature. I found it very useful in Ruby, but I don't see how a paradigm can be built on top of that.
jerf 14y ago
I would also accept "Compositional Programming". Just as the secret to deeply understanding Erlang is to understand that it is primarily about reliability and not about "functional", the secret to understanding where the bulk of the Haskell community is going (except the ones strictly studying theory for theory's sake) is that they are primarily working on composition. Purity and functional and lazy are just some of the buzzwords being turned in that direction. Just as aping Erlang's message passing in $YOUR_FAVORITE_LANGUAGE while missing everything it does for reliability is really missing the point, dropping a map and a fold into your language (and eyeing Monads, then skittering away, though I suspect this is often not because they're too complicated but because the languages are too weak to make them syntactically palatable) is also really missing the point. (Also, mocking Haskell and/or its community for being too theoretical is really missing the point. It's one of the few places where progress is being made on the topic of practical compositional programming. No, the work's not done yet, but, then, that's sort of my point, work is in fact being done. Almost everybody else is just shuffling the same handful of 25-year-old primitives around.)
- monkeyfacebag 14y ago
  I think the real reason Monads haven't been widely adopted is that there isn't a compelling need for them. Laziness, purity and referential transparency are nice-to-haves in most languages, whereas in Haskell, they're need-to-haves. Computers are imperative by nature. They have state. That Haskell has the capability to shield us from that is really, really cool, but that doesn't mean it's necessary to write good software.
  - oconnor0 14y ago
    Except that Monads are compositional (and have reasoning properties) that "normal stateful programming" doesn't allow for.
  - chii 14y ago
    electricity and other modern day conveniences are also not necessary to stay alive, but it sure makes it a lot more comfortable.
Locke1689 14y ago
No offense, but I think you may be pandering to people who don't know what they're talking about. Guido adds first class functions and functools to the standard library and people suddenly start calling Python "functional." The same is probably going to start happening to Java once λ expressions get added. I think functional programming has been most clearly defined as those languages whose base model of computation is the λ-calculus (or F_ω, etc.). Python is not functional because, despite having functional features, the idiomatic way of writing Python mirrors Turing machine computation. If you restricted yourself to only the functional features of Python, well, that would be Python in name, but is that really how people write Python?
- Rickasaurus 14y ago
  The problem is that the vast majority of programmers don't know what they're talking about. Scott Hanselman calls them then silent 99%. They don't blog or comment and they do real work everywhere. The point is terminology matters, especially in how those who can't be bothered to dig deeply come to understand things.
  - Locke1689 14y ago
    Yet your post simply concedes the point--would you not rather explain why people are wrong rather than walk the line yourself to make a point?
    - Rickasaurus 14y ago
      As someone who has regularly given tech talks on functional programming to audiences completely foreign with the ideas involved for almost five years I'm completely sick of explaining it. It takes up far too much of my time when I could be teaching other cool stuff. Calling it Expression Oriented programming is something I've taken to recently and it get people on the right track off the bat. They're focusing on the expressions and not just trying to understand how everything relates to functions.
gruseom 14y ago
I highly recommend Backus' "Can Programming Be Liberated from the von Neumann Style?" as a classic critique of the expression-statement dichotomy (which Backus calls "the von Neumann bottleneck" and then immediately blames himself for rather than von Neumann - Backus of course having led the creation of FORTRAN). www.cs.cmu.edu/~crary/819-f09/Backus78.pdf
- Xcelerate 14y ago
  That critique led to the creation of some function-level languages like FP and FL (nobody's ever heard of them): http://en.wikipedia.org/wiki/Function-level_programming http://en.wikipedia.org/wiki/Function-level_programming Most languages nowadays are value-level. The difference between the two is that function-level programs combine "sub-programs" into one giant new program. Value-level takes primitive types and transforms them into more complex types (I believe this is the same sort of complexity that Rich Hickey disparages).
  - doublec 14y ago
    There's an implementation of FP here: http://www.call-with-current-continuation.org/fp/ http://www.call-with-current-continuation.org/fp/
BadassFractal 14y ago
Hm.. should I stop learning Clojure right this instant? I can't take the "you GOT to learn Erlang/Haskell/Scala/Node/[...] right NOW!" any longer.
- Locke1689 14y ago
  No. Clojure is fine. I actually think that everyone's first functional language should be scheme, but Clojure is not too different. Erlang, Haskell, and Scala all want to sell you on some broader paradigm of functional programming, but they're all still functional at their core and understanding the fundamentals is far more important. Node.js isn't a language, it's just some libraries added on to Javascript.
  - Ixiaus 14y ago
    I highly support the idea of learning Scheme first too - particularly with the Little Schemer books!
lmkg 14y ago
Being a functional language is different than supporting functional programming. A functional program is one that fits the mold he describes: high-order functions as the primary abstraction, pure wherever possible, heavy emphasis on transformation of values rather than updating state. A language that supports functional programming is one where such a program is possible (without too much trouble). A functional language is one where programs that don't fit that mold are difficult or discouraged. To the author's point, supporting functional programming is not hard and most languages do it. Basically all languages, except Java and maybe like Pascal or something. I'm ok with that, though. I'm fine that I can write my own JavaScript functionally, even though other people may not. (Though it's annoying when I interface with less-than-functional third-party libraries.) After all, part of the reason to learn Lisp or Haskell is to make you better at Blub, right? Merely supporting functional programming means that I can still put those lessons to decent use.
- dllthomas 14y ago
  With the addition of unnamed classes, Java supports functional programming - it's just extremely verbose.
- Rickasaurus 14y ago
  > After all, part of the reason to learn Lisp or Haskell is to make you better at Blub, right? What's forcing you to stay in Blub to begin with? There's great same-platform alternatives to everything except for Javascript.
jroseattle 14y ago
Really, the volume of discussion ad nauseum around what normally amounts to syntactic sugar is over the top. I'm not disparaging the functional programming paradigm, but conversation seems to eventually gravitate toward measurements of how functional something is, which seems pointless.
ozataman 14y ago
I have to say, I'm not very fond of hyperbole-laden posts such as this one. People who devote the time and enthusiasm learn the details and hopefully enlighten themselves. People who lack that kind of enthusiasm will likely be confused throughout their lives across many of fronts. What is so surprising, interesting or new about this? Things are often called what they are called for continuity and for legacy reasons. What does it matter if we call it "Functional" vs. "Expression-Oriented"? Will Haskell, ML, Clojure, etc. or their impression on people change overnight because we have a new cool name? I guess a bunch of new/experimental library now claim to be Functional, but so what if they do? Maybe it's a bit too late here, but I don't see the point in this kind of sentiment.
ybother 14y ago
Thank you. This makes me feel much better after reading that awfull object-oriented article.
sherwin 14y ago
I think Ruby does a pretty good job with this, as far as an object oriented main stream language goes. For example, the switch case example from the article can be implemented in ruby as case n: when 1: "one" when 2: "two" etc, and the entire construct can be assigned to a variable because it is an expression. As an aside, ruby 1.9 also supports generic predicates for case statements through lambdas, which is very concise and powerful. Example: https://gist.github.com/838163 https://gist.github.com/838163, source: http://flazz.me/predicates-in-ruby-case-statements http://flazz.me/predicates-in-ruby-case-statements

45 points by Rickasaurus 14y ago

sohn10 14y ago

No.

Rickasaurus 14y ago
Care to elaborate?

smeg 14y ago

Functional programming was alive? Who knew.

monkeyfacebag 14y ago

I will freely admit to thinking I knew something about functional programming after learning about lambdas, map, filter and reduce in Python (and lamenting the language's lack of tail call optimization). Three days with Haskell set me straight.

Ixiaus 14y ago
Haskell, Scheme (a LISP), Erlang, Clojure will all set you straight. What's great is, once you grok one; the others are much easier to get a handle on.

cantankerous 14y ago

I don't get the jump between talking about how "functional" doesn't evoke purity, yet "expression-oriented", does. To be fair, most (probably all) functional languages aren't fully pure. Haskell is probably more pure than most of them, but eventually you have to get things done and dive into the sin bin. The term "functional" really evokes "first class" invokable function symbols that can be passed around in a higher-order kind of way. Everything else is secondary.

Rickasaurus 14y ago
Expression-Oriented evokes purity in that expressions have external facing properties which can be understood and even kept in the type system. If you use global mutation and you don't keep track of it in the type system you can't say much about those properties anymore. You can however use mutation locally and maintain your referential transparency which is a nice way to get around the limits of some not-so-functional-friendly algorithms. I'm planning on writing about that next time around because my tracking shows barely anyone gets to the end of an article beyond a certain length.

kenbot 14y ago

Making things like if/else/switch statements true expressions is a great feature, but I'm not sure it deserves a new foo-oriented programming buzzword.

Rickasaurus 14y ago
The reason I suggested it is because functional has been so badly perverted. We need a term that evokes the actual spirit/philosophy of the language, not just the heritage.
Jebus 14y ago
True, this is just a feature. I found it very useful in Ruby, but I don't see how a paradigm can be built on top of that.

jerf 14y ago

I would also accept "Compositional Programming". Just as the secret to deeply understanding Erlang is to understand that it is primarily about reliability and not about "functional", the secret to understanding where the bulk of the Haskell community is going (except the ones strictly studying theory for theory's sake) is that they are primarily working on composition. Purity and functional and lazy are just some of the buzzwords being turned in that direction. Just as aping Erlang's message passing in $YOUR_FAVORITE_LANGUAGE while missing everything it does for reliability is really missing the point, dropping a map and a fold into your language (and eyeing Monads, then skittering away, though I suspect this is often not because they're too complicated but because the languages are too weak to make them syntactically palatable) is also really missing the point. (Also, mocking Haskell and/or its community for being too theoretical is really missing the point. It's one of the few places where progress is being made on the topic of practical compositional programming. No, the work's not done yet, but, then, that's sort of my point, work is in fact being done. Almost everybody else is just shuffling the same handful of 25-year-old primitives around.)

monkeyfacebag 14y ago
I think the real reason Monads haven't been widely adopted is that there isn't a compelling need for them. Laziness, purity and referential transparency are nice-to-haves in most languages, whereas in Haskell, they're need-to-haves. Computers are imperative by nature. They have state. That Haskell has the capability to shield us from that is really, really cool, but that doesn't mean it's necessary to write good software.
- oconnor0 14y ago
  Except that Monads are compositional (and have reasoning properties) that "normal stateful programming" doesn't allow for.
- chii 14y ago
  electricity and other modern day conveniences are also not necessary to stay alive, but it sure makes it a lot more comfortable.

Locke1689 14y ago

No offense, but I think you may be pandering to people who don't know what they're talking about. Guido adds first class functions and functools to the standard library and people suddenly start calling Python "functional." The same is probably going to start happening to Java once λ expressions get added. I think functional programming has been most clearly defined as those languages whose base model of computation is the λ-calculus (or F_ω, etc.). Python is not functional because, despite having functional features, the idiomatic way of writing Python mirrors Turing machine computation. If you restricted yourself to only the functional features of Python, well, that would be Python in name, but is that really how people write Python?

Rickasaurus 14y ago
The problem is that the vast majority of programmers don't know what they're talking about. Scott Hanselman calls them then silent 99%. They don't blog or comment and they do real work everywhere. The point is terminology matters, especially in how those who can't be bothered to dig deeply come to understand things.
- Locke1689 14y ago
  Yet your post simply concedes the point--would you not rather explain why people are wrong rather than walk the line yourself to make a point?
  - Rickasaurus 14y ago
    As someone who has regularly given tech talks on functional programming to audiences completely foreign with the ideas involved for almost five years I'm completely sick of explaining it. It takes up far too much of my time when I could be teaching other cool stuff. Calling it Expression Oriented programming is something I've taken to recently and it get people on the right track off the bat. They're focusing on the expressions and not just trying to understand how everything relates to functions.

gruseom 14y ago

I highly recommend Backus' "Can Programming Be Liberated from the von Neumann Style?" as a classic critique of the expression-statement dichotomy (which Backus calls "the von Neumann bottleneck" and then immediately blames himself for rather than von Neumann - Backus of course having led the creation of FORTRAN). www.cs.cmu.edu/~crary/819-f09/Backus78.pdf

Xcelerate 14y ago
That critique led to the creation of some function-level languages like FP and FL (nobody's ever heard of them): http://en.wikipedia.org/wiki/Function-level_programming http://en.wikipedia.org/wiki/Function-level_programming Most languages nowadays are value-level. The difference between the two is that function-level programs combine "sub-programs" into one giant new program. Value-level takes primitive types and transforms them into more complex types (I believe this is the same sort of complexity that Rich Hickey disparages).
- doublec 14y ago
  There's an implementation of FP here: http://www.call-with-current-continuation.org/fp/ http://www.call-with-current-continuation.org/fp/

BadassFractal 14y ago

Hm.. should I stop learning Clojure right this instant? I can't take the "you GOT to learn Erlang/Haskell/Scala/Node/[...] right NOW!" any longer.

Locke1689 14y ago
No. Clojure is fine. I actually think that everyone's first functional language should be scheme, but Clojure is not too different. Erlang, Haskell, and Scala all want to sell you on some broader paradigm of functional programming, but they're all still functional at their core and understanding the fundamentals is far more important. Node.js isn't a language, it's just some libraries added on to Javascript.
- Ixiaus 14y ago
  I highly support the idea of learning Scheme first too - particularly with the Little Schemer books!

lmkg 14y ago

Being a functional language is different than supporting functional programming. A functional program is one that fits the mold he describes: high-order functions as the primary abstraction, pure wherever possible, heavy emphasis on transformation of values rather than updating state. A language that supports functional programming is one where such a program is possible (without too much trouble). A functional language is one where programs that don't fit that mold are difficult or discouraged. To the author's point, supporting functional programming is not hard and most languages do it. Basically all languages, except Java and maybe like Pascal or something. I'm ok with that, though. I'm fine that I can write my own JavaScript functionally, even though other people may not. (Though it's annoying when I interface with less-than-functional third-party libraries.) After all, part of the reason to learn Lisp or Haskell is to make you better at Blub, right? Merely supporting functional programming means that I can still put those lessons to decent use.

dllthomas 14y ago
With the addition of unnamed classes, Java supports functional programming - it's just extremely verbose.
Rickasaurus 14y ago
> After all, part of the reason to learn Lisp or Haskell is to make you better at Blub, right? What's forcing you to stay in Blub to begin with? There's great same-platform alternatives to everything except for Javascript.

jroseattle 14y ago

Really, the volume of discussion ad nauseum around what normally amounts to syntactic sugar is over the top. I'm not disparaging the functional programming paradigm, but conversation seems to eventually gravitate toward measurements of how functional something is, which seems pointless.

ozataman 14y ago

I have to say, I'm not very fond of hyperbole-laden posts such as this one. People who devote the time and enthusiasm learn the details and hopefully enlighten themselves. People who lack that kind of enthusiasm will likely be confused throughout their lives across many of fronts. What is so surprising, interesting or new about this? Things are often called what they are called for continuity and for legacy reasons. What does it matter if we call it "Functional" vs. "Expression-Oriented"? Will Haskell, ML, Clojure, etc. or their impression on people change overnight because we have a new cool name? I guess a bunch of new/experimental library now claim to be Functional, but so what if they do? Maybe it's a bit too late here, but I don't see the point in this kind of sentiment.

ybother 14y ago

Thank you. This makes me feel much better after reading that awfull object-oriented article.

sherwin 14y ago

I think Ruby does a pretty good job with this, as far as an object oriented main stream language goes. For example, the switch case example from the article can be implemented in ruby as case n: when 1: "one" when 2: "two" etc, and the entire construct can be assigned to a variable because it is an expression. As an aside, ruby 1.9 also supports generic predicates for case statements through lambdas, which is very concise and powerful. Example: https://gist.github.com/838163 https://gist.github.com/838163, source: http://flazz.me/predicates-in-ruby-case-statements http://flazz.me/predicates-in-ruby-case-statements