[Python-ideas] Improve readability of long numeric literals

[Random832]

On Tue, Feb 9, 2016, at 18:17, Guido van Rossum wrote:
> Indeed, "123 456" is a no-no, but "123_456" sound good. (Not sure
> about "12_34_56" but there are probably use cases for that too.)

For one, not all languages use the same divisions. In many Indian
languages, the natural divisions would be like 1_23_45_678, whereas in
Chinese and Japanese some people may want to use 1_2345_6789, though the
western system is also common.

Also, dare I suggest, 0x_0123_4567_89AB_CDEF? Arbitrary grouping may be
useful in binary constants representing bit fields.

For that matter, for an integer representing a fixed-point fractional
quantity, one may want to use 1_234_567__0000, where the last separator
represents the decimal place. Mathematical publications sometimes group
digits after a decimal place into groups of five, e.g.
Decimal("3.14159_26535_89793_84626") or combine these ideas for
Fraction(3__14159_26535_89793_84626, 10**20)

I don't know that there's any reason to build restrictions into the
language, any more than to require certain integer constants to be in
decimal and others to be in hexadecimal.