[plt-scheme] a few questions (was: Scheme questions?)

From: Gregory Woodhouse (gregory.woodhouse at sbcglobal.net)
Date: Sun Dec 4 20:23:16 EST 2005

On Dec 4, 2005, at 5:19 PM, Gregory Woodhouse wrote:

> Maybe this is an overly esoteric example (in reality, it is very
> fundamental), but suppose we were able to define a function Y (called
> the fixed point combinator, or sometimes the "paradoxical operator")
> that when applied to a function f returns (if it returns at all) a new
> function Y f that *fixes* f. There are many ways to do this, but the
> most famous is
>> (define Y
>     (lambda (z)
>       ((lambda (f) (f f))
>        (lambda (f)
>          (z (lambda (x) ((f f) x)))))))
> (Does your head hurt? That definition certainly makes my head hurt!)

In all fairness, I got the idea of doing this from "The Little Schemer".

Gregory Woodhouse
gregory.woodhouse at sbcglobal.net

"Nothing is as powerful than an idea
whose time has come."
-- Victor Hugo

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