CI: set up linting

.github/workflows/pull_request.yml

@@ -3,6 +3,12 @@ name: Pull Request
 on: [pull_request]
 
 jobs:
+  Lint:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: SwiftFormat
+        run: swiftformat --lint --strict . --reporter github-actions-log
   test-ubuntu-latest:
     name: Test Swift ${{ matrix.swift }} Ubuntu Latest
     strategy:

.swiftformat

@@ -0,0 +1,94 @@
+--allman false
+--binarygrouping none
+--decimalgrouping none
+--disable redundantSelf,trailingClosures
+--elseposition next-line
+--exponentcase uppercase
+--guardelse same-line
+# TODO: add header config
+--header ""
+--hexliteralcase lowercase
+--indent 4
+--indentcase true
+--ifdef no-indent
+--maxwidth 140
+--self insert
+--semicolons never
+--swiftversion 6
+--trimwhitespace always
+--storedvarattrs prev-line
+--computedvarattrs prev-line
+--typeattributes prev-line
+--wrapparameters before-first
+--wrapcollections before-first
+--wraparguments before-first
+
+# Explicitly enable rules to prevent automatic opt-in
+# Generated from `swiftformat --rules` on v0.47.1
+--rules andOperator
+--rules anyObjectProtocol
+--rules blankLinesAroundMark
+--rules blankLinesAtEndOfScope
+--rules blankLinesAtStartOfScope
+--rules blankLinesBetweenScopes
+--rules braces
+--rules consecutiveBlankLines
+--rules consecutiveSpaces
+--rules duplicateImports
+--rules elseOnSameLine
+--rules emptyBraces
+--rules enumNamespaces
+--rules fileHeader
+--rules hoistPatternLet
+--rules indent
+--rules initCoderUnavailable
+--rules leadingDelimiters
+--rules linebreakAtEndOfFile
+--rules linebreaks
+--rules modifierOrder
+--rules numberFormatting
+--rules preferKeyPath
+--rules redundantBackticks
+--rules redundantBreak
+--rules redundantExtensionACL
+--rules redundantFileprivate
+--rules redundantGet
+--rules redundantInit
+--rules redundantLet
+--rules redundantLetError
+--rules redundantNilInit
+--rules redundantObjc
+--rules redundantParens
+--rules redundantPattern
+--rules redundantRawValues
+--rules redundantReturn
+--rules redundantSelf
+--rules redundantType
+--rules semicolons
+--rules sortImports
+--rules spaceAroundBraces
+--rules spaceAroundBrackets
+--rules spaceAroundComments
+--rules spaceAroundGenerics
+--rules spaceAroundOperators
+--rules spaceAroundParens
+--rules spaceInsideBraces
+--rules spaceInsideBrackets
+--rules spaceInsideComments
+--rules spaceInsideGenerics
+--rules spaceInsideParens
+--rules strongOutlets
+--rules strongifiedSelf
+--rules todos
+--rules trailingClosures
+--rules trailingCommas
+--rules trailingSpace
+--rules unusedArguments
+--rules void
+--rules wrap
+--rules wrapArguments
+--rules wrapAttributes
+--rules wrapMultilineStatementBraces
+--rules wrapSingleLineComments
+--rules yodaConditions
+

README.md

@@ -2,5 +2,15 @@
 ## Getting Started
 
 ## Contributing
+### Code Formatting
+This package makes use of [SwiftFormat](https://github.com/nicklockwood/SwiftFormat?tab=readme-ov-file#command-line-tool), which you can install
+from [homebrew](https://brew.sh/). 
 
-## Additional Resources
+To apply formatting rules to all files, which you should do before submitting a PR, run from the root of the repository:
+
+```sh
+swiftformat .
+```
+Formatting is validated with the `--strict` flag on every PR
+
+## Additional Resources 

Sources/Differentiation/Array+Update.swift

@@ -47,4 +47,3 @@ extension Array where Element: Differentiable {
 }
 
 #endif
-

Sources/Differentiation/ArrayDifferentiableView+Collection.swift

@@ -14,30 +14,32 @@ extension Array.DifferentiableView:
     public typealias Element = Array.Element
     public typealias Index = Array.Index
     public typealias SubSequence = Array.SubSequence
-    
+
     @inlinable
     public subscript(position: Index) -> Element {
         _read { yield base[position] }
         set(newValue) { base[position] = newValue }
     }
-    
+
     @inlinable
     public subscript(bounds: Range<Index>) -> SubSequence {
         get { base[bounds] }
         set(newValue) { base[bounds] = newValue }
     }
-    
+
     @inlinable
     public var startIndex: Index { base.startIndex }
-    
+
     @inlinable
     public var endIndex: Index { base.endIndex }
-    
+
     @inlinable
     public init() { self.init(Array<Element>()) }
-    
+
     @inlinable
-    public mutating func replaceSubrange<C>(_ subrange: Range<Self.Index>, with newElements: C) where C : Collection, Self.Element == C.Element {
+    public mutating func replaceSubrange<C>(_ subrange: Range<Self.Index>, with newElements: C)
+        where C: Collection, Self.Element == C.Element
+    {
         base.replaceSubrange(subrange, with: newElements)
     }
 }

Sources/Differentiation/Dictionary+Differentiation.swift

@@ -41,7 +41,7 @@ extension Dictionary where Value: Differentiable {
     {
         // When adding two dictionaries, nil values are equivalent to zeroes, so there is no need to manually zero-out
         // every key's value. Instead, it is faster to create a dictionary with the single non-zero entry.
-        return (self[key], { tangentVector in
+        (self[key], { tangentVector in
             if let value = tangentVector.value {
                 return [key: value]
             }

Tests/DifferentiationTests/DerivativesOfNativeFunctionsTests.swift

@@ -11,7 +11,7 @@ struct DerivativesOfNativeFunctionsTests {
         // the type of a top-level min() function passed into gradient(at:of:).
         @differentiable(reverse)
         func minContainer(_ lhs: Float, _ rhs: Float) -> Float {
-            return min(lhs, rhs)
+            min(lhs, rhs)
         }
         let vwgLessThan = valueWithGradient(at: 2.0, 3.0, of: minContainer)
         #expect(vwgLessThan.value == 2.0)
@@ -20,14 +20,14 @@ struct DerivativesOfNativeFunctionsTests {
         #expect(vwgGreaterThan.value == -2.0)
         #expect(vwgGreaterThan.gradient == (0.0, 1.0))
     }
-    
+
     @Test
     func testMax() {
         // I'm using this container because the compiler can't quite determine
         // the type of a top-level min() function passed into gradient(at:of:).
         @differentiable(reverse)
         func maxContainer(_ lhs: Float, _ rhs: Float) -> Float {
-            return max(lhs, rhs)
+            max(lhs, rhs)
         }
         let vwgLessThan = valueWithGradient(at: 2.0, 3.0, of: maxContainer)
         #expect(vwgLessThan.value == 3.0)
@@ -36,14 +36,14 @@ struct DerivativesOfNativeFunctionsTests {
         #expect(vwgGreaterThan.value == 20.0)
         #expect(vwgGreaterThan.gradient == (1.0, 0.0))
     }
-    
+
     @Test
     func testAbs() {
         // I'm using this container because the compiler can't quite determine
         // the type of a top-level abs() function passed into gradient(at:of:).
         @differentiable(reverse)
         func absContainer(_ value: Float) -> Float {
-            return abs(value)
+            abs(value)
         }
 
         let vwgPositive = valueWithGradient(at: 4.0, of: absContainer)

Tests/DifferentiationTests/Dictionary+DifferentiationTests.swift

@@ -23,25 +23,25 @@ struct DictionaryDifferentiationTests {
         #expect(vwg.value == 3 * aMultiplier + 7 * bMultiplier)
         #expect(vwg.gradient == ["a": aMultiplier, "b": bMultiplier])
     }
-    
+
     @Test
     func testDictionaryReadAndCombineValues() {
         @differentiable(reverse)
         func testFunction(newValues: [String: Double]) -> Double {
-            return 1.0 * newValues["s1"]! +
-            2.0 * newValues["s2"]! +
-            3.0 * newValues["s3"]!
+            1.0 * newValues["s1"]! +
+                2.0 * newValues["s2"]! +
+                3.0 * newValues["s3"]!
         }
-        
+
         let vwg = valueWithGradient(
             at: ["s1": 10.0, "s2": 20.0, "s3": 30.0],
             of: testFunction
         )
-        
+
         #expect(vwg.value == 140.0)
         #expect(vwg.gradient == ["s1": 1.0, "s2": 2.0, "s3": 3.0])
     }
-    
+
     @Test
     func testDictionaryInoutWriteMethod() {
         @differentiable(reverse)
@@ -51,28 +51,28 @@ struct DictionaryDifferentiationTests {
                 mainDict.update(at: key, with: otherValue)
             }
         }
-        
+
         @differentiable(reverse)
         func inoutWrapper(dictionary: [String: Double], otherDictionary: [String: Double]) -> [String: Double] {
             // we wrap the `combineByReplacingDictionaryValues`
             var mainCopy = dictionary
             combineByReplacingDictionaryValues(of: &mainCopy, with: otherDictionary)
             return mainCopy
         }
-        
+
         let vwpb = valueWithPullback(
             at: ["s1": 10.0, "s2": 20.0, "s3": 30.0],
-            ["s1": 2.0],//, "s2": nil, "s3": nil],
+            ["s1": 2.0], // , "s2": nil, "s3": nil],
             of: inoutWrapper
         )
-        
+
         #expect(vwpb.value == ["s1": 2.0, "s2": 20.0, "s3": 30.0])
         // we need to provide a full tangentvector to the pullback hence the keys with zero entries.
         #expect(vwpb.pullback(["s1": 1.0, "s2": 0.0, "s3": 0.0]) == (["s1": 0.0, "s2": 0.0, "s3": 0.0], ["s1": 1.0]))
         #expect(vwpb.pullback(["s1": 0.0, "s2": 1.0, "s3": 0.0]) == (["s1": 0.0, "s2": 1.0, "s3": 0.0], ["s1": 0.0]))
         #expect(vwpb.pullback(["s1": 0.0, "s2": 0.0, "s3": 1.0]) == (["s1": 0.0, "s2": 0.0, "s3": 1.0], ["s1": 0.0]))
     }
-    
+
     @Test
     func testInoutWriteAndSumValues() {
         @differentiable(reverse)
@@ -82,29 +82,29 @@ struct DictionaryDifferentiationTests {
                 mainDict.update(at: key, with: otherValue)
             }
         }
-        
+
         @differentiable(reverse)
         func sumValues(of dictionary: [String: Double]) -> Double {
-            var sum: Double = 0.0
+            var sum = 0.0
             for key in withoutDerivative(at: dictionary.keys) {
                 sum += dictionary[key]!
             }
             return sum
         }
-        
+
         @differentiable(reverse, wrt: dictionary)
         func inoutWrapperAndSum(dictionary: [String: Double], otherDictionary: [String: Double]) -> Double {
             var mainCopy = dictionary
             combineByReplacingDictionaryValues(of: &mainCopy, with: otherDictionary)
             return sumValues(of: mainCopy)
         }
-        
+
         let vwg = valueWithGradient(
             at: ["s1": 10.0, "s2": 20.0, "s3": 30.0],
-            ["s1": 2.0],//, "s2": nil, "s3": nil],
+            ["s1": 2.0], // , "s2": nil, "s3": nil],
             of: inoutWrapperAndSum
         )
-        
+
         #expect(vwg.value == 52.0)
         #expect(vwg.gradient == (["s1": 0.0, "s2": 1.0, "s3": 1.0], ["s1": 1.0]))
     }

Tests/DifferentiationTests/Dictionary+UpdateTests.swift

@@ -25,7 +25,7 @@ struct DictionaryUpdateTests {
         let newB: Double = 7
 
         let valAndGrad = valueWithGradient(at: dictionary, newA, newB, of: writeAndReadFromDictionary)
-        
+
         #expect(valAndGrad.value == newA * aMultiplier + newB * bMultiplier)
         #expect(valAndGrad.gradient == (["a": 0, "b": 0], aMultiplier, bMultiplier))
     }

Tests/DifferentiationTests/Foundation+VJPsTests.swift

@@ -12,7 +12,7 @@ struct FoundationVJPsTests {
         // the type of a top-level min() function passed into gradient(at:of:).
         @differentiable(reverse)
         func atan2Container(_ p1: Double, _ p2: Double) -> Double {
-            return atan2(p1, p2)
+            atan2(p1, p2)
         }
         let vwg = valueWithGradient(at: 1.0, 1.0, of: atan2Container)
         #expect(vwg.value == .pi / 4)

Tests/DifferentiationTests/Sequence+MinMaxVJPsTests.swift

@@ -5,7 +5,6 @@ import Testing
 
 @Suite("Sequence+MinMaxVJPs")
 struct SequenceMinMaxVJPs {
-
     let inputArray = [2.0, 1.0, 3.0]
 
     @Test