What is your evaluation of the proposal?
It contains a relatively simple algorithm, but is common enough as evident by the previous replies. I have written the less general variant count(of:) many times before. (Which, if this proposal gets accepted, can be rewritten as count { $0 == ... }).
It will make code more readable and feels like a natural extension of count and filter(where:) and therefore fits well with the feel and direction of Swift.
It is flexible enough through its use of a closure predicate.
It is tricky to get right, as described in the proposal's motivation section.
How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
A thorough reading.