add Math.parseNum

[floitschG]

We should have a parseNum that parses both ints and doubles.
Example:
Math.parseNum("0xA"); // => 10
Math.parseNum("1.2e3"); // => 1200.0
Math.parseNum("1.0"); // => 1.0
Math.parseNum("1"); // => 1

[lrhn]

I'm not sure I can see a need for parsing something into a type that you don't control. If you don't know what type of number a string holds, how do you even know it's a number. The parseDouble function should allow numbers without a decimal point to be parsed as doubles.

[lrhn]

Removed Type-Defect label.
Added Type-Enhancement label.

[floitschG]

That's like saying that we shouldn't support JSON, because it doesn't require the caller to specify what is read.

[rakudrama]

You know 's' contains a number because 'num.parse(s)' does not throw an exception (or call its onError argument). Just like int.parse and double.parse.

num.parse is useful because there are (on the vm, at least) numbers which can be represented exactly as int, but not as a double, and vice versa. If you want to accept 0.5 and 1000000000000000000001 without truncation error, you need num.parse.

[lrhn]

Added Duplicate label.
Marked as being merged into #8237.