[Haskell-beginners] Re: fixpoint operator for ULC with specific reduction property

ben benedikt.ahrens at gmx.net
Thu Nov 4 11:07:12 EDT 2010



Heinrich Apfelmus wrote:
> ben wrote:
>> I'm looking for a fixpoint operator Z for the untyped lambda calculus
>> that has the property
>>
>> Z g --> g (Z g)
>>
>> for any g.
>> [...]

> I think the Turing fixed point combinator does exactly that. It's
> defined as
> 
>    Theta = (λxf.f(xxf))(λxf.f(xxf))
> [...]


Theta precisely meets my needs.

Thanks a lot.

ben


More information about the Beginners mailing list