Rich Hickey: The Value of Values

The fact that you can't update your house easily is because it is a physical object. Using values doesn't change how easy it is to change your software. If anything, it makes it easier because you know your changes can't screw anyone else up.

> The community is too elitist, the tutorials are math heavy. And the tools are too ancient. Having to use simple text editors and selling them as technologies used to build large applications is a contradictory philosophy.

Careful. Statements like this only create more "elitists" by insulting people. Have you seen leiningen, Counter Clockwise, or La-Clojure? Part of the reason you need all that tooling is because of the objects. If you haven't become proficient in a functional language, can you really say the tooling is insufficient? It's like telling someone their movie sucked without seeing it, or only staying for the first 5 minutes. When I get rid of my Foo, FooImpl, JPAFoo, FooService, FooServiceImpl, FooDao, Bar, BarImpl, etc, the requirements for my editor and tooling suddenly change. If I'm not using big heavy frameworks, I no longer need all those plugins. I don't need to be able to click on my spring configuration and jump to the implementation. When I'm working in repl, I don't need heavy integration with Jetty (for example) because I never need to restart the server. If my restful webservice just needs to be a function that returns a map (ring), then I don't need annotation support, or some framework plugin. If my code is data, my editor already supports both.

I need to move around functions, and compile my code. Code completion? Navigation? Sure, but Emacs, CC, La-Clojure can all do that. I hope you aren't insinuating that Emacs/Slime is a "simple" text editor ;)

Tutorials are their own issue. A new object oriented programming language only needs to teach you their syntax and their API. A Clojure tutorial targeted at someone who has only ever done serious work in an OOPL is going to have to explain not only Clojure, but fundamental concepts related to functional programming. Once you really learn one, the rest all make sense in the same way it's relatively easy to jump around OOPLs.

If you've accepted the technical argument, don't let those other things hold you back. The Clojure community is great, and the Eclipse and IntelliJ stuff has really come a long way.

I just love it when people try to juxtapose "pragmatic" with "math-heavy". Obviously, in the real world no one ever uses math, all they do is print "Hello World" to the screen.

For the avoidance of doubt, when I’m talking about (not) doing away with a time dimension here, I mean from the perspective of the world changing over time as our program runs, not of associating values that effectively last forever with a certain point in time (as in purely functional data structures, version control systems, etc.).

That is, even if we follow the current trend of adopting more ideas from functional programming in mainstream programming languages, I’m saying that I doubt we will ever completely remove variable state, which is what I understand Rich to mean by “place-oriented programming”, or events that must happen in a certain order.

Instead, I think we will learn to control these aspects of our programs better. When we model time-dependent things, we want to have well-specified behaviour based on a clean underlying model, so we can easily understand what our code will do. Today, we have functions and variables, and we have type systems that can stop us passing the colour orange into a function eat(food). Tomorrow, I think we’ll promote some of these time-related ideas to first-class entities in our programming languages too, and we’ll have rules to stop you doing time-dependent things without specifying valid relationships to other time-dependent things. Some of the ideas in that second talk you linked to, like recognising that we’re often modelling a process, are very much what I’m talking about here.

As an aside, it’s possible that instead of adding first-class entities for things like effects, we will instead develop some really flexible first-class concepts that let us implement effects as just another type of second-class citizen. However, given the experience to date with monads in Haskell and with Lisps in general, I’m doubtful that anything short of first-class language support is going to cut it for a mainstream audience. It seems that for new programming styles to achieve mainstream acceptance, some concepts have to be special.

In any case, my hope is that if we make time-related ideas explicit when we care about them, it will mean that when we don’t need to keep track of time, we needn’t clutter our designs/code with unnecessary details. That contrasts with typical imperative programming today, where you’re always effectively specifying things about timing and order of execution whether you actually care about them or not, but when it comes to things like concurrency and resource management the underlying models of how things interact usually aren’t very powerful and allow many classes of timing/synchronisation bug to get into production.

Clojure in Emacs with Slime is hardly a simple text editor. Emacs might be ancient, but that doesn't make it less powerful.

There are also plenty of great documentation for Clojure, Programming Clojure is one, and the online documentation is excellent.