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

Jo Albright me at jo2.co
Thu Jan 7 03:31:10 CST 2016

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.


 Nerd . Designer . Developer
Jo Albright

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