Hello, and what about something like that ? a @ b @ c -> (a @ b) @ c a * b @ c -> (a * b) @ c a @ b * c -> a @ (b * c)
Easy to remember. The *-product has priority to @-product, and then we just to @-product from left to right. An advantage of this is that parsers do job from left to right so I realy think that is a better choice than the weak-right. Christophe BAL 2014-03-17 21:37 GMT+01:00 Russell E. Owen <ro...@uw.edu>: > In article > <CAPJVwBkLww7-ysZB76LMRZ+mmbyN_5T=ym_vu1pjgakrlbq...@mail.gmail.com>, > Nathaniel Smith <n...@pobox.com> wrote: > > > OPTION 1 FOR @: > > Precedence: same as * > > Associativity: left > > My shorthand name for it: "same-left" (yes, very creative) > > > > This means that if you don't use parentheses, you get: > > a @ b @ c -> (a @ b) @ c > > a * b @ c -> (a * b) @ c > > a @ b * c -> (a @ b) * c > > > > OPTION 2 FOR @: > > Precedence: more-weakly-binding than * > > Associativity: right > > My shorthand name for it: "weak-right" > > > > This means that if you don't use parentheses, you get: > > a @ b @ c -> a @ (b @ c) > > a * b @ c -> (a * b) @ c > > a @ b * c -> a @ (b * c) > > > > OPTION 3 FOR @: > > Precedence: more-tightly-binding than * > > Associativity: right > > My shorthand name for it: "tight-right" > > > > This means that if you don't use parentheses, you get: > > a @ b @ c -> a @ (b @ c) > > a * b @ c -> a * (b @ c) > > a @ b * c -> (a @ b) * c > > > > We need to pick which of which options we think is best, based on > whatever > > reasons we can think of, ideally more than "hmm, weak-right gives me warm > > fuzzy feelings" ;-). (In principle the other 2 possible options are > > tight-left and weak-left, but there doesn't seem to be any argument in > > favor of either, so we'll leave them out of the discussion.) > > After seeing all the traffic on this thread, I am in favor of > "same-left" because it is easiest to remember: > - It introduces no new rules. > - It is unambiguous. If we pick option 2 or 3 we have no strong reason > to favor one over the other, leaving users to guess. > > To my mind, being able to easily reason about code you are reading is > more important that hoping to increase efficiency for one common case > when not using parenthesis. > > It also has the advantage that it needs the least justification. > > -- Russell > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
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