[Python-ideas] Respectively and its unpacking sentence

[Paul Moore]

On 27 January 2016 at 17:12, Mirmojtaba Gharibi
<mojtaba.gharibi at gmail.com> wrote:
> innerProduct = sum(map(operator.mul, a, b))
> is much more complex than
> innerProduct += $a * $b

Certainly the second is *shorter*. But it's full of weird "magic"
behaviour that I don't even begin to know how to explain in general
terms (i.e., without having to appeal to specific examples):

- Why does += magically initialise innerProduct to 0 before doing the
implied loop? Would it initialise to '' if a and b were lists of
strings?
- What would *= or -= or ... initialise to? Why?
- What does $a mean, in isolation from a larger expression?
- How do I generalise my understanding of this expression to work out
what innerProduct += $a * b means?
- Given that omitting the $ before one or both of the variables
totally changes the meaning, how bad of a bug magnet is this?
- What if a and b are different lengths? Why does the length of the
unrelated list b affect the meaning of the expression $a (i.e.,
there's a huge context sensitivity here).
- How do I pronounce $a? What is the name of the $ "operator". "*" is
called "multiply", to give an example of what I mean.

Oh, and your "standard Python" implementation of inner product is not
the most readable (which is a matter of opinion, certainly) approach,
so you're asking a loaded question. An alternative way of writing it
would be

innerProduct = sum(x*y for x, y in zip(a, b))

Variable names that aren't 1-character would probably help the
"normal" version. I can't be sure if they'd help or harm the proposed
version. Probably wouldn't make much difference.

Sorry, but I see no particular value in this proposal, and many issues
with it. So -1 from me.
Paul