On 9/17/07, Hugh Perkins <[EMAIL PROTECTED]> wrote: > Just out of curiosity, how could one do something like a factory, so > that by default a library uses, say, Data.Map, but by making a simple > assignment we can switch the library to use a different > implementation? > > (This is alluded to above, but not explicitly stated. I guess it's > too easy, but someone has to ask the newbie questions :-D ) > > I guess we would need to have some sort of "init" function that > returns a state containing our various factories. The user could > update the factories with their own factories if they choose. The > state would need to be passed into each function call to the library > (!) ? > > Or maybe one should store the state in a monad, and run everything > inside a monad? >
Why would you want to do this in Haskell? Please explain in simple language for those of us who haven't been initiated into the secrets of design patterns. Cheers, Tim -- Tim Chevalier * catamorphism.org * Often in error, never in doubt "In fact, a sense of essence is, in essence, the essence of sense, in effect." -- Douglas Hofstadter _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
