Java is the refutation, IMO: it does have a way to express a closure, it's just that the syntax (anonymous class) is laborious. You need to wrap up any mutable variables to be captured in final single-element arrays, and your closure type will be a single-method interface, but the expressiveness is there. The syntax just sucks.

The laborious syntax is what stops you from writing what may be expressed in C# as 'foo.Where(x => x.Name.Length > 10).OrderBy(x => x.Name)' in Java. The equivalent, even using the smaller Javascript syntax of 'function(x) { return x.name.length > 10; }', is tedious. The (current) Java syntax is just silly.

The syntax "weight" of a feature matters. Syntax that's light and unobtrusive invites use. Syntax that's large and clumsy dissuades use, to the point that whole libraries may not come into existence, not because of a lack of expressiveness in the language, but because of aesthetic ugliness.

Lisp has an out here because of macros; almost everything is equally ugly. Many people appear to consider this base level of ugliness unacceptable; others may see it as a flaw of Lisp, because the very malleability of the syntax makes it harder to encode implementation costs in the form of the program.

I don't think it's accurate to say that Java has clunky syntax for closures. Rather, I think it's more accurate to say that Java has no concept of closures. If you want that functionality, you need to roll your own support using existing concepts. C++ before C++11 is the same.

Having never used Common Lisp, I can't say if that's also accurate for your other example.

Edit: ARGH. I forgot string literals in C. So C clearly does have the concept of strings. The problem is that's the only support in the language for that concept. Aside from being able to define string literals, C does not help you with strings at all.

Coffeescript vs Javascript forms a good case study because they largely have the same semantics but with different syntax for key features.

To my mind, the big difference with Coffeescript is the syntax for functions, e.g.

(x) -> x * x

vs.

function (x) { return x * x; }

Coffeescript's syntax eliminates "function" and "return", which significantly lightens the syntactic weight for functions.

I would assume on average that Coffeescripters write significantly more functions than Javascripters (say, for normalization, per bytes of minified JS). This assumption is based on reinforcing selective pressures: Coffeescript encourages programmers to write more functions, and programmers who want to write more functions choose Coffeescript.

Basically, there are some languages whose syntax is so distinctive that it makes a qualitative difference to the experience of programming.

I believe his argument then is that of the following three syntaxes (syntaxen?) to describe closures:

  function(x) { ... }
  \x -> ...
  { |x| ... }

  {|x| x}

  {x| x}

In any case, Ruby's hamburger-notation for closures is well-known by this point, and I'd hardly call it novel anymore. In the case of Python's __special__ methods, the whole point was to discourage people from heavily using them in the first place. Making ugly operations ugly, as it were.

Your point that newcomers might be turned off by a language's syntax remains valid, but you've also demonstrated that newcomers lack the context necessary to be aware of the tradeoffs necessary in language design. But hey, tough shit for language developers, huh? Yes, tough shit indeed. Languages must be familiar enough to attract people, but they must also be sufficiently expressive enough to retain the interest of the people in the community who really matter (the elite hackers and the devoted evangelists), while at the same time seeming novel enough to justify switching away from whatever language you were previously using in that domain.

TL;DR: It's a thorny issue, and simply saying "syntax matters" is an unjust simplification. :)

Java definitely has no syntax for closures, because it has no semantics for function types. It has interfaces and anonymous classes, which you can use to accomplish the same requirement, but the semantics of interfaces are not 100% the same as that of function types. A small example: there's only one function type for a function that takes one int and returns one int, whereas there are infinitely many interfaces you can define to represent that function type and none of them are necessarily interchangeable among themselves.

I think this distinction is important and that this is what the author is talking about when he says "there had better be a way to write a closure somehow!" In Java, there isn't.

For example, C# supports function types, but it can have hundreds of function types (it calls them delegate types) for a function that takes one int and returns one int:

  delegate int Func1(int x);
  delegate int Func2(int x);
  delegate int Func3(int x);

I believe the distinctive feature of closures is closing over (hence the name) the outer lexical environment and binding to variables in the outer environment, in such a way that those variables are available during evaluation. Which is exactly what an anonymous class lets you have (so long as locals in the outer scope are declared final).

To me, the problem is that there is no answer to programming language syntax that pleases everybody. There are general aesthetic principles to follow, but the fundamental questions - semicolons vs. newlines, indentation vs. braces, short vs. long keywords - generate a lot more heat than light. We have to pick one and disappoint somebody.

Note that even in this thread, there is disagreement about whether JavaScript is too terse or too verbose!

However, I also think it's a little sad to limit your selection of languages strictly due to syntactic concerns, without any consideration of features whatsoever. Some languages that are utterly unreadable (I'm looking at you, Haskell! Like trying to eat soup with your hands tied behind your back) have some really cool concepts that, if nothing else, are great to poach for your own favorite language (list comprehensions spring to mind).

  **>
  *>
  *>*
  >*>
  >**

Average Haskell is probably less readable than average Python, because the Haskell community places less emphasis on readability, unfortunately.

Haskell was a particularly obnoxious one - I love a lot of the concepts, but I find it horribly slow for me to read. I got so frustrated with it that I implemented a small little lambda calculus interpreter to play with the concepts because that ended up being an easier way for me to learn them than to wrestle with Haskell.

Personally I don't think Haskell will ever become mainstream to a large extent because it is too hard to read for people who are not maths geeks.

Alan Kay has been studying how children take to programming and many of the ideas from Smalltalk come from these studies.

When designing for children, every part of the user interface, including the syntax of the programming language, matters a lot. For example, he writes, "If we take functional relationships as an example, it has been shown that children readily understand them but have considerable difficulty with variables, and much more difficulty with parameters. The standard math syntax for functions with parameters requires some extra trained chunks to associated dummy names with actual parameters. Some computer languages allow conventions for prefixing the actual parameters with the dummy names. This is good. For younger children, it's likely that making these into complete assignment statements is an even better idea. An object oriented language can use instance variables for a long time before introducing the idea of passing parameters in a method, etc. Having really good trace and single-step visualizations is critical." http://www.donhopkins.com/drupal/node/140

Children have different cognitive needs than adult programmers (and different needs from each other depending on age). But cognitive needs matter in designing programming languages for adults too. I personally take the optimistic (or cynical?) view that we have a lot of room to improve our programming interfaces (not just languages, but the entire programming experience viewed holistically).

Example: Write a function that generates a string of all the numbers in a range from a start and end value.

Java (lots of syntax, many tokens):

String rangeString(int start, int end) { String oni = ""; for(int i = start; i < (1 + end); i++) { oni += String.valueOf(i); } }

Clojure (almost no syntax):

(defn [start end] (apply str (range start (inc end))))

I personally don't think that having less lexical syntax is useful for the things you mention. Lisp has extensible abstract syntax, so overall, it probably has the largest syntax of all.

So by less syntax you mean fewer syntactic forms (parentheses, curly braces, do notation, etc.) and keywords (class, public, etc.) in the language.

I think in general, languages with fewer syntactic forms also have fewer but more powerful abstraction features. Lisps are pretty high up by this measure. They basically only have one abstraction feature: lambda expressions. Other languages have powerful abstraction features but more of them, like Haskell (lambdas, pattern matching, monadic do notation). And others have many but less powerful abstraction features (e.g. Java).

On the one hand, I certainly agree with you that more powerful abstractions make it easier to program. Once you've grokked the abstraction, you only need one brain "chunk" to deal with it freeing up your other chunks to work on the problem. If you need to juggle several different abstractions (e.g. wrap up your closure inside an object inside a class), you have fewer chunks to work on your problem.

On the other hand, people tend to have difficulty learning these higher abstractions in the first place. Alan Kay, in that quote, points out that young children (I think less than ~8 years old) have difficulty with the abstraction of parameterization. In particular they have trouble with mentally corresponding the placement of a parameter in a list with its role in the function. Named parameters make things a bit better, they help the children keep track of the role. Explicit variable assignment (imperative programming) makes it even easier. Of course, as less powerful abstractions, these styles don't tend to scale as well when working on more complex programs.

In general, I think people need help keeping track of specifics while working with higher abstractions until the abstractions become "natural" to them. Programming interfaces, including debugging interfaces, can help with this.

It's a bit of a paradox. When you truly understand an abstraction it tremendously improves the clarity of your programming experience. But without this understanding, abstractions can be a major hindrance.

You may be interested in further exploring "point-free" abstractions. It's kind of the next level up the abstraction ladder from explicitly assigned variables in imperative code, to lambda abstractions with parameters, to functions without the parameters at all. http://www.haskell.org/haskellwiki/Pointfree

Or approach from the concatenative side, http://evincarofautumn.blogspot.com/2012/02/why-concatenativ...

There are two languages I can't do that with. Javascript and Lisp. For me, Lisp and Javascript's syntax is too sparse. I've even used Javascript for a few days every week for the last 10 years and I still can't 'scan' a large code file. I know how it works, I know how to use it, I know the good parts and all the tricks. But I still dread cracking open a misbehaving Jquery plugin or any home grown, even self-written, non-trivial code base in it.

With both of them it's a laborious process of actually having to load the whole code into my head, to remember what other functions are doing, how things are initialized. Perhaps you can call it laziness, but personally I only 'load' a whole code base into my memory when I'm doing significant work with it. It takes time and effort I don't want to have to put in just to make a tweak.

So not being able to just skim read code is intensely annoying.

And that's down to syntax. So to me syntax does matter and it's why I'll keep railing against javascript being the only available language in the browser. It's not just a matter of preference, it's also a matter of productivity. I at least, and I suspect many others, are not very productive with sparse syntactical languages because they're so hard to skim read.

EDIT: Some people have the gift/skill of memorizing things very quickly. I don't, I have the gift/skill of understanding things very quickly, which generally means I can get away with a weak memory. I think a lot of programmers have one of those two skills, but rarely both. Sparse syntax is a bane for the latter.

(Also, have you tried Dart, Coffeescript, or any of the dozens of other languages that compile to Javascript?)

Javascript also suffers from a cowboy layout problem where, for example, the initializer of a class may be anywhere. Most programming languages have established a convention to where it is (the top of the class declaration (e.g. Ruby, Python) or underneath class variables/properties (e.g. Java, C#)).

In Lisp it's even worse as it's not even obvious immediately what is a function or an argument as it's just on the position of the words.

I do keep meaning to give coffeescript a whirl, but feels it solves the symptoms not the underlying cause, so it's not that high on my 'try it' list.

On a different note, I have abstained from commenting on Rust's attitude toward keyword names but aside #2 just bothers me. Naming conventions matter and since Rust may possibly become used in the future it may inspire some new generation of users to learn to program. 20 years later they will start writing their own languages and think "Hey, I used 'ret' in Rust and that brings back good memories so I'll just keep using it!". Truly an embarrassing part of hacker culture.

Its like you will not work for a company because it have clean toilets, but if they have dirty toilets you wont work for them

If you find this logic familiar, its because i am basing it on motivation theory