[Haskell-cafe] Re: Incremental trasnformations (not Haskell topic)

frantisek kocun frantisek.kocun at gmail.com
Sun Dec 28 15:07:07 EST 2008

Still nobody? Maybe I didn't write it clear. So one more time:

I have a list of numbers (say Int)
numberList = [1:Int,2,3,1,2,6,7,8]
and a number
sumOfNumberList = sum numberList
and here comes the question. Imagine the list numberLists is mutable (that's
why in topic is "not Haskell question") so the calculation doesn't occur
only once but every time something changed in the list (listener pattern).
(If the lis tis java List and Int is java Integer, every acces to list
should trigger event to its listeners, but if I use list of another objects
e.g. Item with value, every access to list should trigger event to its
listeners as well as every modification of object Item should triggers its
listeners (list) and that in turn triggers its listeners) How to make
transformation of often used functions (map, sum, forall, filter, exists) to
listeners in OO language? Is there anything (any tool, any paper, any
blog...) about it?



PS If nobody answers I really stop asking non Haskell questions in this
mailling list:)
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