Swift should allow “switch” and “if” in expressions

Originator:jlieske
Number:rdar://17246104 Date Originated:09-Jun-2014 10:58 PM
Status:Duplicate Resolved:
Product:OS X SDK Product Version:Xcode6 beta: Version 6.0 (6A215l)
Classification:Enhancement Reproducible:Always
 
The Swift language supports many of the principles of functional programming, such as higher-order functions, immutable values, and pattern matching.  One gap in the functional support is for conditional expressions.  

Swift includes the ternary “? :” operator from C, but that operator does not support the “if let” test with binding that is so useful.  Swift only allows “if” or “if let” in a statement, not an expression.  Likewise, Swift only supports “switch” in a statement.

I propose adding syntax to Swift that allows conditional expressions with the full binding support of “if” and “let”.  As a strawman, the syntax could look like the following:

let result = (if let myValue = someOptional {myValue.calculateSomething()}
              else {calculateSomethingElse()})

let result = (switch someEnum {
    case let .Success(value): .Some(value)
    case let .Error(error): nil
})

Comments

Apple closed as duplicate of rdar://16169366

By jlieske at June 21, 2014, 7:36 p.m. (reply...)

A more longwinded argument for switch expressions, with some arguments regarding syntax: http://openradar.appspot.com/17258614

By alexisgallagher at June 10, 2014, 11:06 p.m. (reply...)

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