[Haskell-cafe] Re: Couple of formal questions

Michael Karcher usenet at mkarcher.dialup.fu-berlin.de
Thu May 1 11:58:43 EDT 2008


Wouter Swierstra <wss at cs.nott.ac.uk> wrote:
> Hi Creighton,
> > Where could I find a proof that the initial algebras & final  
> > coalgebras of CPO coincide?  I saw this referenced in the  
> > "Bananas.." paper as a fact, but am not sure where this comes from.
> I couldn't find the statement you are referring to in "Functional  
> Programming with Bananas, Lenses, Envelopes, and Barbed Wire" - but  
> I'm not sure if this holds for every CPO.

Probably he was referring to the last paragraph of the introduction:

  Working in CPO has the advantage that the carriers of intial algebras
  and final co-algebras coincide, thus there is a single data type that
  comprises both finite and infinite elements.

Regards,
  Michael Karcher



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