[swift-evolution] Allowing Characters for use as Custom Operators

[Félix Cloutier]

In a discussion about adding $ to the operator character set (it currently is an identifier character), Chris said that any token must be unambiguously either an identifier or an operator even before operators are "discovered", and that's why the identifier character sets and operator character sets have no overlap right now.

"as" and "is" are not operators, they're keywords that were hard-coded into the grammar.

Félix

> Le 7 janv. 2016 à 04:31:10, Jo Albright via swift-evolution <swift-evolution at swift.org> a écrit :
> 
> As my obsession grows with custom operators. I have come across wanting to use small words or 1-2 alphabetical characters as custom operators. I noticed that “as” and “is” are character based operators and figured it wouldn’t hurt to propose the allowance of character based custom operators.
> 
> Here are my reasons for allowing them:
> 
> 1. easier to read “within” vs “>*<“ or “|*|” 
> 
> 2. potential opportunity to build an educational library to help explain expressions (see below)
> 
> infix operator plus { associativity left precedence 200 }
> 
> public func plus (lhs: Int, rhs: Int) -> Int {
>     
>     return lhs + rhs
>     
> }
> 
> let totalApples = 5 plus 5
> 
> 3. potential to write more like a sentence (this isn’t as high of a need, but again a good for entry into the language) 
> 
> postfix operator oz { }
> postfix operator cup { }
> postfix operator gal { }
> 
> public func oz (inout _ lhs: Double) -> Double {
>     
>     return lhs
>     
> }
> 
> public func cup (inout _ lhs: Double) -> Double {
>     
>     return lhs *= 8.0 
>     
> }
> 
> public func gal (inout _ lhs: Double) -> Double {
>     
>     return lhs *= 128.0
>     
> }
> 
> let totalLiquidInOunces = 5oz plus 2cup plus 1gal
> 
> 
> I spent awhile looking to make sure this hasn’t been proposed before. I apologize if it is a repeat.
> 
> Thanks
> 
>  Nerd . Designer . Developer
> Jo Albright
> 
> 
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20160107/ff3a5947/attachment.html>