[swift-evolution] Proposal: Adding precedence option for prefix and postfix operators

David Sweeris davesweeris at mac.com
Wed Jan 20 02:17:48 CST 2016

TI graphing calculators (at least the ones I've used have different buttons for binary and prefix -, does that count? I'm not sure if they behave differently WRT precedence, though.

What if an operator's precedence could be changed by specific functions? Like +(Int, Int) -> Int is 100 (or whatever the default is), but +(MyType, MyType) has precedence 3?

Does that break anything?

> On Jan 19, 2016, at 22:54, Jason Nielsen via swift-evolution <swift-evolution at swift.org> wrote:
> If you can find a mathematically oriented text that distinguishes between binary and prefix in regards to "-" I'll buy you a salad.
>> On Mon, Jan 18, 2016 at 11:58 AM, Sune Foldager <cyano at me.com> wrote:
>> > On 17 Jan 2016, at 18:19, Jason Nielsen via swift-evolution <swift-evolution at swift.org> wrote:
>> > I'm afraid that is not a correct statement.  There is no arguing that -3^2 is -9 and that -3^2 and 0-3^2 are equivalent mathematically.  Exponentiation has higher precedence than - and subtraction is definitely an operator so -3^2 != (-3)^2.
>> A minus sign can represent both a part of an integer, a binary operator called subtraction and sometimes a prefix operator called negation, as far as mathematics go.
>> -Sune
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