[Haskell-cafe] attoparsec and backtracking

[Evan Laforge]

On Fri, Mar 15, 2013 at 8:49 PM, Niklas Hambüchen <mail at nh2.me> wrote:
> Is it not possible to add an alternative (no pun intended) to <|> that
> supports the semantics Evan wants?

I assume it's the performance thing.  Presumably it would need to pass
an extra flag with to the failure continuation to tell it to not
retry, though that doesn't sound so bad.  Actually, Bryan's response
here:

https://github.com/bos/attoparsec/issues/42

makes it sound like he's not opposed to <||> on performance grounds,
just that <|> is more intuitive.  I agree in general, but not in the
case of error msgs!  So maybe I just need to see if I can make a patch
to add <||>, sounds like Johan at least would be into that.