Re: [Haskell-cafe] questions on lazy pattern, StateT monad

Am Mittwoch, 23. November 2005 20:42 schrieb Wolfgang Jeltsch:

Am Mittwoch, 23. November 2005 19:02 schrieb Fan Wu: [...]

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But it is still not clear to me why lazy pattern is used here. Any ideas?

Let's discuss this for State instead of StateT because this makes the discussion easier.

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Oops, I've answered a question you didn't ask. I haven't looked at your message carefully enough and thought that you were refering to the implementation of (>>=) while in fact you were refering to the implementation of mplus. But I think the reasons behind lazy pattern usage in the mplus implementation are similar to those behind lazy pattern usage in the (>>=) implementation.

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Best wishes, Wolfgang