[Haskell-cafe] Re: Is lazyness make big difference?

Allan Clark a.d.clark at ed.ac.uk
Thu Feb 15 08:07:34 EST 2007

> i.e. to use Monad.Writer in stead of Monad.State. The point is that for
> example 'typedProgram' does not really depend on the contents of 'log',
> but the dependencies in your code don't express this. One should switch from
>   Log -> (a, Log)
> to
>   (a, Log -> Log)
> or even
>   (a, Log)
> if Log already has a natural monoid structure.
Yes of course you're quite right, in general I would have the last 
version ie (a, Log).
I did not wish to muddy the example, but probably it was not helpful to 
have 'typedProgram' depend on the contents of 'log'.


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