marcrasi

import TensorFlow

protocol MyLayer: Differentiable {
  associatedtype Input: Differentiable

  @differentiable
  func forward(_ x: Input) -> Tensor<Float>
}

extension MyLayer {

marcrasi

// MARK: - Some differentiable array manipulation functions used in the algorithms.

extension Array where Element: Differentiable {
  @differentiable(vjp: _vjpSwappedAt)
  func swappedAt(_ i: Int, _ j: Int) -> Array {
    var tmp = self
    tmp.swapAt(i, j)
    return tmp
  }

marcrasi

Differentiating Class Methods

marcrasi@

Last updated: 5/21/19

Problem

When c has class type with a method named f, Swift dispatches c.f() at runtime by looking for the concrete implementation of method inside a "vtable" referenced by c.

marcrasi

import TensorFlow

/// A Simple RNN Cell.
public struct SimpleRNNCell<Scalar: TensorFlowFloatingPoint>: RNNCell {
    public var weight: Tensor<Scalar>
    public var bias: Tensor<Scalar>

    @noDerivative public var stateShape: TensorShape {
        return TensorShape([1, weight.shape[1]])
    }

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protocol A {}

struct Wrapper<T> {
  var t: T
}

extension Wrapper: A where T: A {}

func inner<T: A>(_ t: T) {}

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struct MyTensor<T: Equatable & AdditiveArithmetic>: Equatable & AdditiveArithmetic {
  var value: T
}

extension MyTensor : Differentiable where T : AdditiveArithmetic & Differentiable {
  typealias TangentVector = MyTensor
  typealias CotangentVector = MyTensor
  typealias AllDifferentiableVariables = MyTensor
  func tangentVector(from cotangentVector: CotangentVector) -> TangentVector {
    return cotangentVector

marcrasi

Incorrect reconstructed type for $sxq_Iegnr_D
Original type:
(sil_function_type type=@differentiable @callee_guaranteed (@in_guaranteed τ_0_0) -> @out τ_0_1)
Reconstructed type:
(sil_function_type type=@callee_guaranteed (@in_guaranteed τ_0_0) -> @out τ_0_1)
Stack dump:
0.	Program arguments: /usr/local/google/home/marcrasi/swift-base-merge/build/Ninja-RelWithDebInfoAssert/swift-linux-x86_64/bin/swift -frontend -c -filelist /tmp/sources-716834 -supplementary-output-file-map /tmp/supplementaryOutputs-c055d6 -disable-objc-attr-requires-foundation-module -target x86_64-unknown-linux-gnu -disable-objc-interop -sdk / -I /usr/local/google/home/marcrasi/swift-base-merge/build/Ninja-RelWithDebInfoAssert/swift-linux-x86_64/./lib/swift/linux/x86_64 -warn-swift3-objc-inference-complete -warn-implicit-overrides -enable-library-evolution -g -module-cache-path /usr/local/google/home/marcrasi/swift-base-merge/build/Ninja-RelWithDebInfoAssert/swift-linux-x86_64/./module-cache -module-link-name swiftCore -nostdimport -parse-st

marcrasi

extension Array where Element: Differentiable {
    /// Views the array as the differentiable product manifold of `Element` with itself `count` times.
    public struct DifferentiableView: Differentiable {
        /// The array that we are viewing.
        public var base: [Element]

        /// Construct a view of the given array.
        public init(_ base: [Element]) { self.base = base }
        
        // MARK: - Differentiable conformance.

marcrasi

public struct ProductSpaceVector<Element> {
  public var elements: [Element]
  public init(_ elements: [Element]) { self.elements = elements }
}

extension ProductSpaceVector : Equatable where Element : Equatable {
  public static func == (lhs: ProductSpaceVector, rhs: ProductSpaceVector) -> Bool {
    return lhs.elements == rhs.elements
  }
}

marcrasi

public struct ProductSpaceVector<Element> {
  public var elements: [Element]
  public init(_ elements: [Element]) { self.elements = elements }
}

extension ProductSpaceVector : Equatable where Element : Equatable {
  public static func == (lhs: ProductSpaceVector, rhs: ProductSpaceVector) -> Bool {
    return lhs.elements == rhs.elements
  }
}