[Haskell-cafe] The container problem

Andrew Coppin andrewcoppin at btinternet.com
Sat Sep 27 13:21:20 EDT 2008

Brandon S. Allbery KF8NH wrote:
> On 2008 Sep 27, at 12:41, Andrew Coppin wrote:
>> I'm not sure how that qualifies set as "not really a true monad 
>> anyway" - but then, I don't know what a monad is, originally. I only 
>> know what it means in Haskell.
> I think you read him backwards:  Map and Set are category-theory 
> ("true") monads, but they can't be Haskell Monads because Haskell 
> isn't expressive enough to represent more than a subset of 
> category-theoretical monads.

Ah, OK. That makes more sense then...

What (if anything) do we do about that?

I'm not actually bothered about every possible monad being representable 
as such in Haskell. I'd just like Set to work. ;-)

>> Also... Who or what is an Oleg, and why do I keep hearing about it? ;-)
> Oleg Kiselyov.  http://okmij.org/ftp/
> He's somewhat legendary in the Haskell community for his ability to 
> make Haskell do what people think it can't, and his tendency to 
> program at the type level instead of at the value level like most 
> people.  :)

Ah - so the "Prolog programs as type signatures" thing is *his* fault?! ;-)

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