Comments on: Deriving the Y combinator http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/ This dirt was a building before Tue, 09 Mar 2010 11:44:32 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Answer My Searches » Blog Archive » Mini Searches with Answers http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-3854 Answer My Searches » Blog Archive » Mini Searches with Answers Mon, 30 Nov 2009 17:34:34 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-3854 [...] Somewhat Coherent Explanation of What is a Y CombinatorI guess it’s a way to use recursion without calling the function by name. I’m not sure why you would ever need to do that though. [...] [...] Somewhat Coherent Explanation of What is a Y CombinatorI guess it’s a way to use recursion without calling the function by name. I’m not sure why you would ever need to do that though. [...]

]]> By: Nick Black http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-3778 Nick Black Wed, 21 Oct 2009 08:30:43 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-3778 a very solid article -- keep writing! -- but i liked this most of all: "be aware I’m mostly writing this to force myself to understand something by writing it down. If you get anything out of it, consider it a bonus." if you don't mind, i'm appropriating this for my own wiki, posthaste. a very solid article — keep writing! — but i liked this most of all:

“be aware I’m mostly writing this to force myself to understand something by writing it down. If you get anything out of it, consider it a bonus.”

if you don’t mind, i’m appropriating this for my own wiki, posthaste.

]]> By: Rodney King http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-3611 Rodney King Wed, 09 Sep 2009 11:34:56 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-3611 Excellent post -- thanks for writing it. One curiousity in your webpage itself - you use "<code>" for the code bits. I'd have thought: one tag or the other, but not both.</code> Excellent post — thanks for writing it. One curiousity in your webpage itself – you use “" for the code bits. I'd have thought: one tag or the other, but not both.

]]> By: JavaScript: The Good Parts - Push cx http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-3502 JavaScript: The Good Parts - Push cx Tue, 09 Jun 2009 12:09:09 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-3502 [...] Y combinator, which allows creating recursive anonymous functions. There’s a blog post with a nice derivation, but it seems oddly absent from the [...] [...] Y combinator, which allows creating recursive anonymous functions. There’s a blog post with a nice derivation, but it seems oddly absent from the [...]

]]> By: -= Linkage 2008.02.08 =- http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-3428 -= Linkage 2008.02.08 =- Mon, 26 Jan 2009 15:38:53 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-3428 [...] Deriving the S-combinator<br/> [...] [...] Deriving the S-combinator<br/> [...]

]]> By: Lambdaphant / Playing Catch-up http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-2808 Lambdaphant / Playing Catch-up Sun, 10 Feb 2008 18:36:47 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-2808 [...] some other stuff that I've been reading. At Arc fn Ken has a great post about the internals of Arc. This post helped me get a better grasp of the Y [...] [...] some other stuff that I’ve been reading. At Arc fn Ken has a great post about the internals of Arc. This post helped me get a better grasp of the Y [...]

]]> By: Sp3w http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-2802 Sp3w Fri, 08 Feb 2008 13:45:58 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-2802 [...] Deriving the S-combinator [...] [...] Deriving the S-combinator [...]

]]> By: Scott Williams http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-2790 Scott Williams Wed, 06 Feb 2008 23:31:09 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-2790 Thank for the iterative explanation. I think I have my brain wrapped around it. When exactly in the real world is this useful though? Thank for the iterative explanation. I think I have my brain wrapped around it. When exactly in the real world is this useful though?

]]> By: oliver http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-2780 oliver Wed, 06 Feb 2008 04:06:14 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-2780 Slightly off topic a faster way to do self recursion without a dependency on a global variable is to use a named function (using your example): var factorial = function f(x) { return x == 0 ? 1 : x * f(x-1); }; where 'f' will be scoped only to the function body... functionally this is equivalent to: var factorial = function (x) { var f = arguments.callee; return x == 0 ? 1 : x * f(x-1); }; Albeit slightly more efficient (you'd need to be using f a lot to make the lookup cost significant). --Oliver Slightly off topic a faster way to do self recursion without a dependency on a global variable is to use a named function (using your example):
var factorial = function f(x) {
return x == 0 ? 1 : x * f(x-1);
};

where ‘f’ will be scoped only to the function body… functionally this is equivalent to:
var factorial = function (x) {
var f = arguments.callee;
return x == 0 ? 1 : x * f(x-1);
};

Albeit slightly more efficient (you’d need to be using f a lot to make the lookup cost significant).

–Oliver

]]> By: Chris Schneider http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/comment-page-1/#comment-2776 Chris Schneider Tue, 05 Feb 2008 23:05:14 +0000 http://blog.jcoglan.com/2008/01/10/deriving-the-y-combinator/#comment-2776 Thank you for your explanation. It was very clear, the clearest I've seen for this. I'll have to reread it later to really get it, but you did a great job describing and deriving. Thank you for your explanation. It was very clear, the clearest I’ve seen for this. I’ll have to reread it later to really get it, but you did a great job describing and deriving.

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