[plt-scheme] Y Combinator Exercise

On Nov 16, 2005, at 12:59 PM, Matthias Felleisen wrote:

> In the monograph on reduction semantics [Felleisen & Flatt], we had  
> some sample calculations using the Y combinator along the lines of  
> what John points out. Use reductions to show ((Y mk-!) 2) is 2.  
> Then show them that the fixpoint equation helps. Reprove the first  
> one and wow it all gets easier. Then show them that you need a  
> calculus (=) and that reductions (->) are no longer enough for  
> this. Puzzle: can you design a cbv Y-like combinator that doesn't  
> use 'backwards' reductions. -- Matthias

<humility>
Okay, now I'm confused.  Isn't cbv Y _itself_ a Y-like combinator  
that doesn't use 'backwards' reductions?
</humility>

John

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2430 bytes
Desc: not available
URL: <http://lists.racket-lang.org/users/archive/attachments/20051116/5884c507/attachment.p7s>