Add IntSet, a (inefficient) implementation of IndexSet

Package.swift

@@ -8,7 +8,7 @@ let package = Package(
         .library(name: "SkipLib", type: .dynamic, targets: ["SkipLib"]),
     ],
     dependencies: [
-        .package(url: "https://source.skip.tools/skip.git", from: "0.7.28"),
+        .package(url: "https://source.skip.tools/skip.git", from: "0.7.29"),
         .package(url: "https://source.skip.tools/skip-unit.git", from: "0.4.5"),
     ],
     targets: [

Sources/SkipLib/IntSet.swift

@@ -0,0 +1,89 @@
+// Copyright 2023 Skip
+//
+// This is free software: you can redistribute and/or modify it
+// under the terms of the GNU Lesser General Public License 3.0
+// as published by the Free Software Foundation https://fsf.org
+
+// SKIP SYMBOLFILE
+
+#if SKIP
+
+public struct IntSet: BidirectionalCollection, SetAlgebra {
+    public typealias Index = Int
+    public typealias Element = Int
+
+    public init(integersIn range: any RangeExpression<Int>) {
+    }
+
+    public init(integer: Int) {
+    }
+
+    public init() {
+    }
+
+    @available(*, unavailable)
+    public var rangeView: Any {
+        fatalError()
+    }
+
+    @available(*, unavailable)
+    public func rangeView(of range: any RangeExpression<Int>) -> Any {
+    }
+
+    public func integerGreaterThan(_ integer: Int) -> Int? {
+        return nil
+    }
+
+    public func integerLessThan(_ integer: Int) -> Int? {
+        return nil
+    }
+
+    public func integerGreaterThanOrEqualTo(_ integer: Int) -> Int? {
+        return nil
+    }
+
+    public func integerLessThanOrEqualTo(_ integer: Int) -> Int? {
+        return nil
+    }
+
+    @available(*, unavailable)
+    public func indexRange(in range: any RangeExpression<Int>) -> Range<Int> {
+        fatalError()
+    }
+
+    public func count(in range: any RangeExpression<Int>) -> Int {
+        return 0
+    }
+
+    public func contains(integersIn range: any RangeExpression<Int>) -> Bool {
+        return false
+    }
+
+    public func contains(integersIn indexSet: IntSet) -> Bool {
+        return false
+    }
+
+    public func intersects(integersIn range: any RangeExpression<Int>) -> Bool {
+        return false
+    }
+
+    public mutating func insert(integersIn range: any RangeExpression<Int>) {
+    }
+
+    public mutating func remove(integersIn range: any RangeExpression<Int>) {
+    }
+
+    public func filteredIndexSet(in range: any RangeExpression<Int>, includeInteger: (Int) throws -> Bool) rethrows -> IntSet {
+        return self
+    }
+
+    public func filteredIndexSet(includeInteger: (Int) throws -> Bool) rethrows -> IntSet {
+        return self
+    }
+
+    @available(*, unavailable)
+    public mutating func shift(startingAt integer: Int, by delta: Int) {
+    }
+}
+
+#endif

Sources/SkipLib/Skip/Array.kt

@@ -126,10 +126,11 @@ class Array<Element>: RandomAccessCollection<Element>, RangeReplaceableCollectio
         if (other === this) {
             return true
         }
-        if (other as? Array<*> == null) {
+        if (other !is Sequence<*>) {
             return false
         }
-        return other.collection == collection
+        @Suppress("UNCHECKED_CAST")
+        return elementsEqual(other as Sequence<Element>)
     }
 
     override fun hashCode(): Int {