Talk:Fixed point combinator

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[edit] Klop combinator

Did anybody notice that the fixed point combinator by Klop as given here is wrong? Did anybody actually try it? I used it to test my lambda-calculus interpreter and I was thinking of a bug in it, until I found the correct definition somewhere on the web: [1] (look for $). There should be 26 L's, not 28 as given here. The problem is that many web pages directly copy from the Wikipedia text, and give the same (wrong) definition. I don't know whether the page was vandalized long ago, or it was a genuine transcription error. Fixed. --positron 10:14, 7 March 2006 (UTC)

I don't think anybody did try it. Should've just removed it when I did a big cleanup a while back, I suppose. Thanks for the fix. —donhalcon╤ 14:52, 7 March 2006 (UTC)

[edit] Dumbing Down

Could you dumb it down a shade? --Mike Schiraldi 01:53, 27 Jun 2005 (UTC)

  • I think the first paragraoh is misleading the reader into thinking about fixpoints as real values, whereas the following paragraph is talking about a fixpoint in function space. It takes a bit of a conceptual leap to understand the latter, and the first paragraph doesn't particularly help...
I've submitted a rewrite that should be a lot easier to understand. --bmills 18:00, 21 October 2005 (UTC)

I suspect that some of that stuff is graffiti, but I'm not expert enough to say for sure. Will someone please check on it? --unknown

[edit] Y Combinator

It seems like the Y Combinator should have its own page.

[edit] Example

Why does the example mix (a b (c d)) and a(b)(c(d)) notation? It would be a lot clearer, I think, if it stuck to (a b (c d)), and put ( ) on the lambdas as well. It would also be nice to state the final result (fact = (fix ...)). Shinobu 06:57, 8 November 2006 (UTC)

  • The example also appears to be wrong. It uses just part of the church numeral, and confusingly uses f to mean two different things. Can anyone confirm this? (New guy, reluctant to change/break anything) CarpeCerevisi 11:46, 8 February 2007 (UTC)

[edit] Huh?

Note that the Y combinator is intended for the call-by-name evaluation strategy, since (Y g) diverges (for any g) in call-by-value settings

Can somebody explain this? What does call-by-name versus call-by-value even mean in the context of lambda calculus? Isn't call-by-name always the case in lambda calculus? Why does Y g diverge in call-by-value? What does 'diverge' mean in this context? All these things are totally non-obvious. JulesH 19:12, 11 November 2007 (UTC)

Also, the "Example" section refers to something described as the "fix" operator, which hasn't been defined. JulesH 19:25, 11 November 2007 (UTC)