[Haskell-cafe] Splitting off many/some from Alternative

[Bryan O'Sullivan]

On Sun, Dec 11, 2011 at 9:18 PM, Gregory Crosswhite
<gcrosswhite at gmail.com>wrote:

>
> It is only recently that I have been able to grok what some and many are
> even about (I think), and they seem to only make sense in cases where
> executing the Alternative action results in a portion of some input being
> consumed or not consumed.  "some v" means "consume at least one v and
> return the list of items consumed or fail", and "many v" means "consume
> zero or more v and return the list of items consumed or the empty list of
> none are consume".
>

There is absolutely no implication of consuming anything in the definitions
of many or some. This is how they happen to behave when used in the context
of some parsing libraries, but that's all. If many or some always go into
an infinite loop for some Alternative instance, then I suspect that the
instance itself is either broken or shouldn't exist.
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