Returning to an old hobbyhorse: Migrating higher order function names to comply with API guidelines

Evolution Pitches
27

We should focus on 'training" swift's code completion to suggest a new symbol to take precedence over an imported discouraged symbol when importing a new package.
There are a couple of issues that would need to be addressed:

  1. How do we "train" the code completion logic to pick an implementation over another?
  2. Raise the precedence of some symbols in overloading resolution implicitly via the same mechanism so that when somebody calls a symbol with that name then it gets picked up by a "shim" library that was imported.
  3. We still need a way to disambiguate overloads on the call site (out of scope)

Intellisence allows custom training that could function in a similar way as the bellow suggestions but instead of arbitrary being able to train code completion we would sort of "tag" our preference using an attributed.

We can address 1 and 2 with an attribute that will inform the overload resolution and code completion that should take precedence:
@symbolPrecedence(overloadRename: "mapping(_:)", higherThan: Swift , lowerThan: OtherLib)

  • overloadRename: The name of an method similar to the rename property
  • higherThan, lowerThan : a library name that would function in a similar way as "Precedence Group Declaration" . Hopefully this can be strongly typed in some form via import

Imagine I wanted to create new package that contains all the new suggested name changes, lets call this package SwiftBoost.

\\ SwiftBoost Library

import Swift
import OtherLib


extension CollectionOrArrayEtc {
...
@available(swift 5.3)
@symbolPrecedence(overloadRename: "mapping(_:)", higherThan: Swift , lowerThan: OtherLib)
@inlinable public func mapping<T>(_ transform: (Character) throws -> T) rethrows -> [T] { ... }

@symbolPrecedence higherThan: Swift , lowerThan: OtherLib)
@available(*, deprecated: 5.3, renamed: "mapping(_:)", message: "Please use mapping")
@inlinable public func map<T>(_ transform: (Character) throws -> T) rethrows -> [T] { ... }

...
}

// New Lib ABC
import SwiftBoost

var someArray = ...

someArray.mapping(...)
In ABC when I start typing map, the symbol mapping should be the first choice on code completion.

some.map(...)
In ABC if I were to choose map anyway then I will get a warning that is coming from SwiftBoost.

some.Swift::map(...)
some.SwiftBoost::map(...)

It would be really helpful if we could disambiguate which package the symbol is being picked up.

Reference:

https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID380

[Pitch] @completionHandlerAsync attribute