More builtins - inf, nan

[Paul "LeoNerd" Evans]

Since we now have `true` and `false` builtins, in addition to the
ever-present `undef`, I wonder if folks would want two more for
slightly nicer working with floating-point numbers, being ways to get
inf and NaN.

I could write up a PPC on this but honestly it's barely 5 minutes to
actually just implement it in a PR - thoughts on whether I should just
do it?

[Philippe Bruhat (BooK)]

Post by Paul "LeoNerd" Evans
Since we now have `true` and `false` builtins, in addition to the
ever-present `undef`, I wonder if folks would want two more for
slightly nicer working with floating-point numbers, being ways to get
inf and NaN.

Don't we have those already?

Post by Paul "LeoNerd" Evans
Special floating point: infinity (Inf) and not-a-number (NaN)
Floating point values include the special values "Inf" and "NaN",
for infinity and not-a-number. The infinity can be also negative.

What would be those add?

(Also, possibly spell infinity as "Inf" rather that "inf".)