Re: [Haskell-cafe] Re: Why?

Yes I remember when watching Erik Meijer's videos on Channel9 he said a similar thing: "laziness in the presence of side effects makes your head explode"... I guess the recent Microsoft Rx framework for .NET (that permits impure push-based functional reactive programming with LINQ) will soon show if the average software engineer can successfully combine side effects with laziness... Imperative/OO programming is full of guidelines to help the programmer avoid side effects: "use local state as much as possible", "never use mutable globals", "use single point of definition to avoid double out of sync data", "encapsulate encapsulate encapsulate", etc On Thu, Dec 10, 2009 at 4:38 PM, Eugene Kirpichov wrote:

2009/12/10 John D. Earle :

...

My intuition says that laziness and purity are distinct whereas yours says that purity is a necessary condition. This is what needs to be reconciled.

Mixing impurity and laziness makes code whose behavior is too hard to understand. So, there is no theoretical reason not to mix them, but there is a practical one.

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I believe that everyone is thinking that lazy evaluation and strict evaluation are similar activities whereas they are profoundly different. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

-- Eugene Kirpichov Web IR developer, market.yandex.ru _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe