Open Radar

 
Summary:
The swift standard library supplies a number of convenient methods for modifying standard structs. These methods appear to be largely consistently named where direct verbs mutate structs, and adjectives return new copies with the transformation applied.

Array has a number of methods which violate this convention.
While `sort` and `sorted` adhere to the convention, `filter`, `reverse`, and `join` do not. Methods such as map which return a collection of elements of a different type than the original are obviously exempt from this expectation.

This makes working with arrays difficult as the documentation must be frequently consulted to determine if a method mutates the array or not. This is particularly bothersome because the compiler provides no warning that `myArray.reverse()` did not do anything.

Steps to Reproduce:
Write code to mutate an array by reversing it.

Expected Results:
The code I expect to mutate the array causes a mutation in place.

Actual Results:
The code silently returned a new array, which was thrown away by the running program.

Regression:
Many languages Swift has heritage from have good conventions for denoting mutability, such as Ruby/Scheme’s `!` suffix.