We've found with lens in practice it is actually quite useful to have (&) bind just a touch tighter than ($), but yes, we do tend to discourage users from mashing them together:

makeMyLenses = makeLensesWith $ 
  defaultRules & ... & ... & ...

-Edward



On Thu, Oct 10, 2013 at 2:18 PM, David Menendez <dave@zednenem.com> wrote:
On Thu, Oct 10, 2013 at 1:08 PM, Wvv <vitea3v@rambler.ru> wrote:
We want to combine all of them, like

xs # map $ (+ 3) . snd

And xs $$ map $ (+ 3) . snd  - don't look nice.

That's actually a pretty good example of why this is a bad idea. You can't know which argument is being applied first unless you know the precedence levels.

In fact, according to the fixity you initially proposed, that translates to

(xs # map) $ (+3) . snd

The corrected version, xs # (map $ (+3) . snd), isn't much better. Even with the parentheses, it's needlessly confusing. ($) and (#) should never appear in the same expression, or at least they shouldn't apply arguments to the same function. It would be like using (.) and (>>>) together.

--
Dave Menendez <dave@zednenem.com>
<http://www.eyrie.org/~zednenem/>

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