[swift-evolution] [proposal] default func ==(_:_:)

[Jan E. Schotsman]

Feature name - provide default func ==(_:_:) for types declared  
Equatable

Author: Jan E.Schotsman

Introduction:

If all of a type's stored properties are Equatable it makes sense for  
Swift to provide a default equality implementation.

Motivation:

In a project where many large types are defined that need to be  
Equatable it gets cumbersome to write explicit equality functions for  
all types.

Proposed solution

If a type is declared Equatable, all its stored properties are  
Equatable and no func ==(_:_:) is defined by the developer the  
compiler will synthetisize a memberwise equality function.
(Recursiveness of this procedure is almost automatic)

Impact on existing code

There is no impact on existing code. Equality functions equal to the  
default implementation can simply be removed.