On Thu, Mar 20, 2014 at 9:07 AM, Robert Kern <robert.kern@gmail.com> wrote:
I think the operator-overload-as-DSL use cases actually argue somewhat for right-associativity. There is no lack of left-associative operators for these use cases to choose from since they usually don't have numeric or bitwise operations defined for them. Right-associativity adds some diversity into the ecosystem and opens up some design space.
Whether or not this is true, I think we should assign this argument ~zero weight for purposes of the present discussion. That's because: - We haven't been asked to figure out the best design of @ for Python overall, we've been asked to report back on what design of @ will be best for the numeric community, since that's where we have special expertise that python-dev lacks. Python-dev is entirely capable of then taking our report as input and then having a debate about how much weight to give to these other possible uses. - And anyway, my impression is that python-dev will give these other possible uses ~zero weight anyway -- if they thought random DSL operators were important for their own sake, they would have added @ long ago :-). Maybe if we say "we literally do not care at all what @'s precedence and associativity are", then it will matter as a tie-breaker, but first I don't think it's true that we don't care, and second even if it were then my guess is that the argument for consistency with the other operators would be a stronger tie-breaker. -- Nathaniel J. Smith Postdoctoral researcher - Informatics - University of Edinburgh http://vorpus.org