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It seems to be a popular notion that adding constructs common in FP is somehow a modernization of C++ or Java. FP isn't a set of features, it's a style of progr

It seems to be a popular notion that adding constructs common in FP is somehow a modernization of C++ or Java. FP isn't a set of features, it's a style of programming. It's actually a bad idea to try to retrofit a paradigm on top of an existing language. You should build tools that do one thing well, and if they no longer suit your style of programming, you should switch to a tool that is designed to fit your needs. A lot of my reasoning was criticizing the JVM itself, not Java. VM languages add unnecessary complexity in the post container world where ephemerality and kernel APIs (containers) can give the same advantages, although I think Kotlin and Clojure and remarkably good languages.

coldtea 8y ago
>It seems to be a popular notion that adding constructs common in FP is somehow a modernization of C++ or Java. FP isn't a set of features, it's a style of programming. And historically, nobody cared for that style of programming in its pure form (where "nobody" is in the casual sense: a few FP-lovers, but not the 95% of working programmers). From 1960 to today it remains niche in its pure form, even the most popular language following it fully (e.g. Clojure or similar) is still a niche language. We found out, on the other hand, that people care for mixing that style of programming with OO, imperative, reactive, and other styles. And that's what modern JS, Java, C#, Rust, etc (even C++) give us. And since FP is a style, it can be followed quite effectively in almost any language -- as long as it has some basic features, which, as you observed, Java has added.
- ilovecaching 8y ago
  Pedantically, you can't just redefine a term to suit your need calling something "pure" or "unpure". There are many other styles of programming that are data oriented and are a better definition for Rust and some circles of Javascript than functional, but ergonomics of composition and partial application leads to something far short of FP. > We found out, on the other hand, that people care for mixing that style of programming with OO, imperative, reactive, and other styles. Which is why you forgot to mention Scala, which shows us how great such a promise land can be when we try to please everyone. > JS, Java, C#, Rust, etc (even C++) give us. Out of the languages you mentioned, only certain circles of Javascript (React) and Rust are arguably functional as I mentioned above. Javascript has been a real exception to the rule in how its lack of real class support left a vacuum for some FP. C++, C#, Java, and the majority of Javascript are object oriented and always will be.
  - iainmerrick 8y ago
    Pedantically, you can't just redefine a term to suit your need calling something "pure" or "unpure". No, I think they are using those terms correctly. In FP, “pure” means absolutely no side-effects. So if you add an FP-style library to an existing imperative language, that’s “impure”.
    - ilovecaching 8y ago
      That's not the context in which the word was used, but it's a fair point. I have worked professionally with Haskell, and while I am not good at it (my forte is Erlang which is what I would consider "close to functional"), other developers I have worked with were very good, and watching them code in non functional languages and listen to how they thought about solving problems is were I developed the idea that adding a few features doesn't make a language functional.
- willtim 8y ago
  > And since FP is a style, it can be followed quite effectively in almost any language. It's not black and white. FP is more like a spectrum, with pure functional programming more towards the opposite end, just before total functional programming. Put another way, adding lambdas to Java does not make it like Haskell. Even Scala cannot effectively be used as Haskell substitute, as some in that community eventually realised. It remains to be see how much of FPs benefits (composition, abstraction, reasoning) can be fully realised in languages with rampant side-effects and mutation.
_bxg1 8y ago
> It's actually a bad idea to try to retrofit a paradigm on top of an existing language. You should build tools that do one thing well, and if they no longer suit your style of programming, you should switch to a tool that is designed to fit your needs. I categorically disagree. Nearly any program has pieces that benefit from OOP and pieces that benefit from FP and everything in-between. The most prevalent and useful languages support multiple paradigms (C++ is a mess for other reasons).

coldtea 8y ago

>It seems to be a popular notion that adding constructs common in FP is somehow a modernization of C++ or Java. FP isn't a set of features, it's a style of programming. And historically, nobody cared for that style of programming in its pure form (where "nobody" is in the casual sense: a few FP-lovers, but not the 95% of working programmers). From 1960 to today it remains niche in its pure form, even the most popular language following it fully (e.g. Clojure or similar) is still a niche language. We found out, on the other hand, that people care for mixing that style of programming with OO, imperative, reactive, and other styles. And that's what modern JS, Java, C#, Rust, etc (even C++) give us. And since FP is a style, it can be followed quite effectively in almost any language -- as long as it has some basic features, which, as you observed, Java has added.

ilovecaching 8y ago
Pedantically, you can't just redefine a term to suit your need calling something "pure" or "unpure". There are many other styles of programming that are data oriented and are a better definition for Rust and some circles of Javascript than functional, but ergonomics of composition and partial application leads to something far short of FP. > We found out, on the other hand, that people care for mixing that style of programming with OO, imperative, reactive, and other styles. Which is why you forgot to mention Scala, which shows us how great such a promise land can be when we try to please everyone. > JS, Java, C#, Rust, etc (even C++) give us. Out of the languages you mentioned, only certain circles of Javascript (React) and Rust are arguably functional as I mentioned above. Javascript has been a real exception to the rule in how its lack of real class support left a vacuum for some FP. C++, C#, Java, and the majority of Javascript are object oriented and always will be.
- iainmerrick 8y ago
  Pedantically, you can't just redefine a term to suit your need calling something "pure" or "unpure". No, I think they are using those terms correctly. In FP, “pure” means absolutely no side-effects. So if you add an FP-style library to an existing imperative language, that’s “impure”.
  - ilovecaching 8y ago
    That's not the context in which the word was used, but it's a fair point. I have worked professionally with Haskell, and while I am not good at it (my forte is Erlang which is what I would consider "close to functional"), other developers I have worked with were very good, and watching them code in non functional languages and listen to how they thought about solving problems is were I developed the idea that adding a few features doesn't make a language functional.
willtim 8y ago
> And since FP is a style, it can be followed quite effectively in almost any language. It's not black and white. FP is more like a spectrum, with pure functional programming more towards the opposite end, just before total functional programming. Put another way, adding lambdas to Java does not make it like Haskell. Even Scala cannot effectively be used as Haskell substitute, as some in that community eventually realised. It remains to be see how much of FPs benefits (composition, abstraction, reasoning) can be fully realised in languages with rampant side-effects and mutation.

_bxg1 8y ago

> It's actually a bad idea to try to retrofit a paradigm on top of an existing language. You should build tools that do one thing well, and if they no longer suit your style of programming, you should switch to a tool that is designed to fit your needs. I categorically disagree. Nearly any program has pieces that benefit from OOP and pieces that benefit from FP and everything in-between. The most prevalent and useful languages support multiple paradigms (C++ is a mess for other reasons).