milseman

This is a pitch for some low-level Unicode operations to enable libraries to implement their own String-like functionality and types. The purpose of this API is to present low-level core components out of which libraries can make types and higher-level API (i.e. tools for tool-makers).

I'm interested in hearing about capabilities that libraries may need and getting design feedback.

Introduction

String performs many Unicode operations using a mix of internal and publicly available functionality in the stdlib. The stdlib provides some limited general-purpose Unicode API, though this is a very dusty corner of the stdlib. We want to enable libraries to vend their own String-like types and functionality.

milseman

prefix operator ^

public prefix func ^<T>(_ t: T) -> T? { return .some(t) }

//
// Numbers
//

milseman

State of String: ABI, Performance, Ergonomics, and You!

Hello, I’ve been working on implementing, optimizing, and improving String in preparation for ABI stability, and I thought I’d share the current status of String in Swift 5 and some potential directions to go. This is the product of conversations with open source contributors and my colleagues on the Swift standard library team at Apple.

The primary area of focus is stabilizing String’s ABI, but we’d be remiss if we couldn’t also fit in performance and ergonomic improvements. String’s ergonomics in particular is one area where we think the status quo is woefully inadequate, and over half of this email is devoted to that topic. At the end, there’s a section about a community initiative that we hope can help users of String as well as guide future development.

(Note: I’m sending this to swift-dev because much of the contents revolve around implementation concerns. I’ll also cross-reference on swift-evolution and swift-users. See also the [StringManife

milseman

This is now hosted in the repo: https://github.com/apple/swift-experimental-string-processing/blob/main/Documentation/BigPicture.md

milseman

// The below will be a customization point on Collection. For the purposes of
// this gist, we'll fake/approximate it with static overloads

extension Collection {
  /// Returns an index `distance` positions prior to `i` if it exists.
  ///
  /// Other methods such as `index(_:offetBy:)` must not be passed a negative
  /// offset if the collection is bidirectional. This method will perform a
  /// negative offset even if the collection is not bidirectional, by using a
  /// less efficient means. `BidirectionalCollection` customizes this with a

milseman

FilePath Syntactic Operations

• Authors: Michael Ilseman, Saleem Abdulrasool
• Implementation: PR-14
• Previous version: version 1, changes

Introduction

FilePath appeared in System 0.0.1 with a minimal API. This proposal adds API for syntactic operations, which are performed on the structure of the path and thus do not consult with the file system or make any system calls. These include inspecting the structure of paths, modifying paths, and accessing individual components.

milseman

FilePath Syntactic Operations

Introduction

FilePath appeared in System 0.0.1 with a minimal API. This proposal adds API for syntactic operations, which are performed on the structure of the path and thus do not consult with the file system or make any system calls. These include inspecting the structure of paths, modifying paths, and accessing individual components.

Additionally, this proposal greatly expands Windows support and enables writing platform-agnostic path manipulation code.

Future Work: Operations that consult the file system, e.g. resolving symlinks.

milseman

// Eat/seek/peek

extension Collection where SubSequence == Self, Element: Equatable {
    mutating func eat() -> Element {
        defer { self = self.dropFirst() }
        return peek()
    }
    mutating func eat(_ n: Int) -> SubSequence {
        let (pre, rest) = self.seek(n)
        defer { self = rest }

milseman

Changes in v2

• Removed .start and .end, now all OffsetBounds are built from .first and .last.
  • Simplifies usage and learnability. .last + 1 representing the end is mostly only relevant to documentation.
  • Better delineates OffsetBound abstraction and terminology from indices.
• Added RangeReplaceableCollection convenience overloads, as well as subscript setters.
  • .insert(at:), .remove(at:), etc.,

milseman

struct StringFormatters {
    var text = "Hello, World!"
}

/*

This is the master template for fprintf format string functionality.
For development purposes only

```