[Haskell-beginners] [Haskell-cafe] select :: [(Float, a)] -> a -- Weighted stochastic selection - help?

Nicolas Pouillard nicolas.pouillard at gmail.com
Sat Sep 6 04:04:31 EDT 2008


Excerpts from C.M.Brown's message of Fri Sep 05 22:12:05 +0200 2008:
> > Can you give an example? I don't see how that can be done using
> > Control.Monad.State(.Strict).State, unless invocations of put or modify are
> > considered side effects.
> 
> Actually, yes, sorry; I do see your point. I guess it's just IO then.

Technically, even the IO monad is pure, that's just the runtime-system
that consume your 'main' function that perform effects (and unsafeP...).

That's an important point to grasp about the way we do effects in a pure
language.

Once we've understood that point one tend to be a little less precise and
consider IO as effect-full.

Best regards,

-- 
Nicolas Pouillard aka Ertai
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