rxwei

/// A type equality guarantee is capable of safely casting one value to a
/// different type. It can only be created when `S` and `T` are statically known
/// to be equal.
struct TypeEqualityGuarantee<S, T> {
  private init() {}

  /// Safely cast a value to the other type.
  func cast(_ value: T) -> S {
    return value as! S
  }

rxwei

Swift Charts Framework Internship at Apple

Note: Applications are now closed.

Apple's Swift Charts team is now looking for interns for 2024!

This is a paid, in-person internship in Cupertino, California. While most internships last 3 months, starting in May or June, the start date and internship length are flexible. Internships are restricted to students pursuing a Bachelor's, Master's, or PhD degree. Students must be enrolled in school in

rxwei

See the official Differentiable Programming Manifesto instead.

rxwei

Make Swift AD support all numpy functions via Autograd/JAX

In the Python module:

let autograd = Python.import("jax.grad")

extension PythonObject {
  @differentiable(wrt: args, vjp: _vjpDynamicallyCall)
  @discardableResult

rxwei

//============================================================================//
// Part 1. StoredPropertyIterable
// This models the purely static layout of a struct.
//============================================================================//

// This is an implementation detail that is required before PAT existentials are
// possible.
protocol _StoredPropertyIterableBase {
  static var _allStoredPropertiesTypeErased: [AnyKeyPath] { get }
  static var _recursivelyAllStoredPropertiesTypeErased: [AnyKeyPath] { get }

rxwei

Upstreaming Swift AutoDiff

Author: Richard Wei (rxwei@google.com) on behalf of the Swift for TensorFlow team

Last updated: October 2, 2019

Overview

The differentiable programming feature (AutoDiff) has been incubated in the 'tensorflow' branch of apple/swift since December 2017 and released as part of the Swift for TensorFlow toolchains. The Differentiable Programming Mega-Proposal, which serves as a manifesto, received general positive feedback from the community, but there is a long way between receiving conceptual approval and obtaining Swift Evolution approval of such a large feature. We would like to merge the pieces into the 'master' branch under a gate to further development and bake the feature on master, just like Apple develops its major features

rxwei

// To be shared on Swift Forums.
// Compile with:
//     swiftc -Xllvm -enable-experimental-cross-file-derivative-registration -enable-experimental-forward-mode-differentiation main.swift

// MARK: - Make integers differentiable

extension Int: Differentiable {
    public typealias TangentVector = Int
}

rxwei

import TensorFlow

protocol Differentiable {
    ...
    var zeroTangentVectorInitializer: () -> Self { get }
}

extension Tensor where Scalar: TensorFlowFloatingPoint {
    var zeroTangentVectorInitializer: () -> Self {
        { [shape = self.shape] in Tensor(zeros: shape) }

rxwei

@differentiable
func nested_loop(_ x: Float, count: Int) -> Float {
  var outer = x
  outerLoop: for _ in 1..<count {
    outer = outer * x

    var inner = outer
    var i = 1
    while i < count {
      inner = inner + x

rxwei

// AD__dot__pullback_src_0_wrt_0_1
sil hidden [ossa] @AD__dot__pullback_src_0_wrt_0_1 : $@convention(thin) (@in_guaranteed Float, @owned _AD__dot_bb0__PB__src_0_wrt_0_1) -> (@out Vector, @out Vector) {
// %0                                             // user: %202
// %1                                             // user: %203
// %2                                             // user: %65
// %3                                             // user: %66
bb0(%0 : $*Vector, %1 : $*Vector, %2 : $*Float, %3 : @owned $_AD__dot_bb0__PB__src_0_wrt_0_1):
  %4 = alloc_stack $Tracked<Float>                // users: %233, %232, %196, %188, %7
  %5 = witness_method $Tracked<Float>, #AdditiveArithmetic.zero!getter.1 : <Self where Self : AdditiveArithmetic> (Self.Type) -> () -> Self : $@convention(witness_method: AdditiveArithmetic) <τ_0_0 where τ_0_0 : AdditiveArithmetic> (@thick τ_0_0.Type) -> @out τ_0_0 // user: %7
  %6 = metatype $@thick Tracked<Float>.Type       // user: %7