[Python-ideas] Make map() better

[David Mertz]

We're not going to break every version of Python since 0.9 because
Javascript does something a certain way.  Whatever might be better
abstractly, this is well established.

As to adding a `.map()` method to *every* iterable... just how would you
propose to do that given that it's really easy and common to write custom
iterables.  How do you propose to change every class ever written by users?
(including ones that already define `.map()` with some other meaning than
the one you suggest)?

On Wed, Sep 13, 2017 at 8:09 AM, Jason H <jhihn at gmx.com> wrote:

> The format of map seems off. Coming from JS, all the functions come
> second. I think this approach is superior.
>
> Currently:
> map(lambda x: chr(ord('a')+x), range(26)) # ['a', 'b', 'c', 'd', 'e', 'f',
> 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
> 'v', 'w', 'x', 'y', 'z']
>
> But I think this reads better:
> map(range(26), lambda x: chr(ord('a')+x))
>
> Currently that results in:
> TypeError: argument 2 to map() must support iteration
>
> Also, how are we to tell what supports map()?
> Any iterable should be able to map via:
> range(26).map(lambda x: chr(ord('a')+x)))
>
> While the line length is the same, I think the latter is much more
> readable, and the member method avoids parameter order confusion
>
> For the global map(),
> having the iterable first also increases reliability because the lambda
> function is highly variable in length, where as parameter names are
> generally shorter than even the longest lambda expression.
>
> More readable: IMHO:
> map(in, lambda x: chr(ord('a')+x))
> out = map(out, lambda x: chr(ord('a')+x))
> out = map(out, lambda x: chr(ord('a')+x))
>
> Less readable (I have to parse the lambda):
> map(lambda x: chr(ord('a')+x), in)
> out = map(lambda x: chr(ord('a')+x), out)
> out = map(lambda x: chr(ord('a')+x), out)
>
> But I contend:
> range(26).map(lambda x: chr(ord('a')+x)))
> is superior to all.
>
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