Quoting Joachim Durchholz <j...@durchholz.org>: > Actually I'd like to *remove* a special case: That ² is to be interpreted as 2
But it's NOT a special case. You can use any character with No property as a numeric literal. That's. The. Entire. Rule that governs the behaviour under examination in this ticket. No special cases. No "unless followed by a superscript char". Just: "Any `No` char is good" There's quite a bunch of these chars: https://gist.github.com/Whateverable/d94b6a42532a4c1262df794d9be799f3 So just as you can write: <Zoffix> m: say ⅓² <camelia> rakudo-moar 0a1008: OUTPUT: «0.111111» You can write: <Zoffix> m: say ²² <camelia> rakudo-moar 0a1008: OUTPUT: «4» In BOTH of these cases a No numeral is used with a ² "postfix n" operator. Entirely identical. No special casing. > But before deciding how to deal with them: What are the > supposed/expected meaning of the following constructs? > 3² > x² > ² > 3² should be 3 squared, i.e. 9 Indeed that is it. Same as in regular mathematics. The 3 raised to power 2: <Zoffix> m: say 3² <camelia> rakudo-moar 0a1008: OUTPUT: «9» > x² to be x squared, i.e. an expression Indeed that is it. Same as in regular mathematics. `x` raised to power 2: <Zoffix> m: my \x = 42; say x² <camelia> rakudo-moar 0a1008: OUTPUT: «1764» > ² confuses me, does that even make sense? It's the same as the stated rule above: "Any `No` char can be used as a numeric literal" <Zoffix> m: dd [.unival, .uniprop] with '²' <camelia> rakudo-moar 0a1008: OUTPUT: «[2, "No"]» As you can see above, ² is indeed a `No` char, and it's Unicode numeric value is 2, which is the numeral you get. > What happens actually is that in ³², the ³ is taken as a base and the > ² as an exponent (that's why we're getting ³² == 9. > If the superscripts were handled just like normal literal digits, the > result should be 32. No, the description above is incorrect and conflates `Nd` Unicode characters that can be used as **digits** with `No` chars that can be used as **numerals**. They can't be used as individual **digits**. And since Perl 6's expects a term here to be followed by an op, there's no ambiguity about what `²` in `³²` is supposed to be interpreted as. It's an operator, so we have a `No` numeral followed by an operator; or 3 raised to the power of 2. > *If* Perl6 is interpreting superscripts specially (and it already > does) That statement is incorrect. It doesn't. >, *then* I expect it to recognize a bare ² as an exponent That's incorrect, because it expects a term in that position, not an operator. > since bare exponents do not make any sense They do. In that context they're a term and you can use ANY `No` character as a numeral. > I.e. no specialcasing at all beyond what's already there. There's no special casing. There's just one rule: "you can use `No` characters as numerals". Simple. Elegant. Easy to remember.
