[Haskell-cafe] Re: a regressive view of support for imperative programming in Haskell

David Roundy droundy at darcs.net
Mon Aug 13 13:26:53 EDT 2007

On Mon, Aug 13, 2007 at 01:27:45PM -0300, Isaac Dupree wrote:
> David Roundy wrote:
> >The only cost is that
> >this syntax relies on the do notation, and thus makes the desugaring of
> >that do notation slightly more complicated when used.
> If I understand correctly,
>  do
>   blah
>   f (do
>            foo
>            bar (<- action)
>      )
>   blah
> has an ambiguity: which do-block is the action bound in?  I can easily 
> imagine myself being frustrated at having to refactor my code if the 
> defined answer is not the one I want at the moment.

It doesn't have an ambiguity, because it's defined to be bound in the
innermost do loop.  This isn't a new concept, the <- syntax in the existing
do notation has the same behavior.
David Roundy
Department of Physics
Oregon State University

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