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A clear definition of the Y combinator in 28 words
There are some corners of Computer Science that are so esoteric that
descriptions of them don't make sense on first reading (or even the hundredth
reading)—for example, the Y combinator [1]. That's why I always treasure
crystal clear explanations like this one:
> If you have a language that supports anonymous lambda functions, there may
> be occasions where you want to build a recursive lambda. The Y Combinator
> specifically enables this.
>
> If you don't like the Y Combinator for some reason, you can always make
> sure that your recursive functions are always named, but it's often
> convenient to declare lambdas in place instead of naming them, and this is
> no less true of recursive lambdas.
>
“Y Combinator in Python [2]”
(Don't let the term “anonymous lambda function” trip you up—all that means is
a function (or subroutine if you will) that doesn't have a name)
I also find it amusing that while Lisp (generally considered one of the
highest programming languages in existence) requires the Y combinator [3] (if
that link is too obtuse, how about a page about Lamba Calculus [4]? Okay,
that's obtuse as well), Forth [5], a language originally developed to control
radio telescopes and has a history of being rather low level, doesn't need
the Y combinator! You can write anonymous lambda functions all day in Forth
with no problem (yes, I'm easily amused).
[1]
http://en.wikipedia.org/wiki/Y_combinator
[2]
http://programming.reddit.com/info/2k4eh/comments/c2k6f2
[3]
http://www.t3x.org/sketchy/vol1/sl21.html
[4]
http://www.mactech.com/articles/mactech/Vol.07/07.05/LambdaCalculus/
[5]
http://en.wikipedia.org/wiki/Forth_(programming_language)
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