[Haskell-cafe] Re: Converting IO [XmlTree] to [XmlTree]

Martijn van Steenbergen martijn at van.steenbergen.nl
Mon Apr 27 16:19:23 EDT 2009

Tillmann Rendel wrote:
> Achim Schneider wrote:
>> In other words:
>> 1) Explain Pointed
>> 2) Explain Functor
>> 3) Explain Applicative
>> 4) Explain Monad
> Why Pointed first? Functor seems more useful and more basic.

They are in order of power: every monad is an applicative; every 
applicative is a functor; every functor is pointed.

Though I can't think of any non-functor pointiness at the moment.


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