I was noodling around with some Ruby the other day, and all of a sudden I ran into a situation where I wanted to do a partial function application. But how do you do that in Ruby? It can certainly be done, but it felt very awkward to me and made my code less readable than the non-partially-applied alternatives. So I didn't do it.
For me, higher-order functions in Ruby are the language's only blemish. It seems almost unfair to ding Ruby for that, because Ruby (at least since 1.9.x) does higher-order functions pretty admirably. It's just not as elegant as the rest of the language.
Ruby has set an extremely high bar. The lack of ceremony in the language makes it extremely readable. The purity of its "everything is an object" stance makes it very writable. And its pervasive methods of introspection make it amazingly powerful.
But why did I even have the urge to make a partially applied function? Because I've been doing a lot of JavaScript lately, and JavaScript is all about the functions.
Ruby and JavaScript take sort of opposite approaches to object properties vs. methods. When you want to reach into an object in Ruby, you always talk to a method. So-called "properties" on Ruby objects are really just getter and setter methods with a little syntactic sugar applied.
In JavaScript, objects mostly only have properties. A "method" in JavaScript is just a property that happens to be a function. (You can define real getters and setters in modern versions of JavaScript, but browser support is not yet pervasive.)
Which approach is better? I would have to say Ruby's. JavaScript seems more fragile in its property-centricity. For example, if you want to pass a method as a callback in JavaScript you have to think about weather it needs to be called as a method or if it is OK to be called as a stand-alone function. If it needs to be called on a particular object you end up wrapping it in another function.
When it comes to JavaScript's advantage - higher-order functions - Ruby sort of cheated. By making a special case of passing a single function (a block), Ruby made the 80% use case extremely easy and simple.
So is Ruby the best language? Well, I probably wouldn't have worried about higher-order functions so much if I wasn't using JavaScript. What other blemishes might Ruby have that I just never run into? I guess it's not surprising that you can only compare languages that you have really used.
But Ruby is definitely the best language that I know.
