Román González wrote: > On Thu, Sep 16, 2010 at 2:12 PM, Ben Franksen > <ben.frank...@online.de>wrote: > >> Sjoerd Visscher wrote: >> > But StrictIncl can't be a pointed functor, only endofunctors can be >> > pointed. >> >> Could someone tell me what exactly a pointed functor is? I googled but >> did not find a definition. > > Here you will find what a Pointed Functor would be => > http://haskell.org/sitewiki/images/8/85/TMR-Issue13.pdf > > Look up for the Typeclassopedia, start reading functor, next thing you > will find is the Pointed typeclass
Thanks for the link. What I actually wanted was a mathematical definition, though. From the TMR article I gather that a pointed functor could be defined as an endo-functor F: C -> C together with a natural transformation pure: Id -> F where Id: C -> C is the identity functor. No additional laws (beside naturality of pure) are imposed. Right so far? Why is this an interesting structure? Cheers Ben _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
