compilation fix

src/aoc/Common/Bfs/Bfs.cs

@@ -28,13 +28,6 @@ public class AdhocAdjacency<T>(Func<T, IEnumerable<(T newState, int weight)>> fu
 			public IEnumerable<(T newState, int weight)> GetAdjacent(T pos) => function(pos);
 		}
 
-		public delegate bool Target<in T>(T state); // ITarget?
-
-		public static class Targets
-		{
-			public static Target<T> Value<T>(T value) 
-				=> state => Equals(value, state);
-		}
 
 		public static BfsBuilder<T> StartWith<T>(T start)
 		{

src/aoc/Common/Bfs/Folder.cs

@@ -48,17 +48,6 @@ public class AdhocFold<T, TRes>(Func<TRes, Path<T>, (TRes, TraversalResult)> fun
 	 => function(acc, path);
 }
 
-public class SearchFold<T>(Bfs.Common.Target<T> target) : IFold<T, Result<T>>
-{
-	public (Result<T>, TraversalResult) Fold(Result<T> acc, Path<T> path)
-	{
-		var (current, _) = path.PathList;
-		if (target(current.Item))
-			return (new Found<T>(path), TraversalResult.Interrupt);
-		return (new NotFound<T>(), TraversalResult.Continue);
-	}
-}
-
 public enum TraversalResult
 {
 	Continue,

src/aoc/Common/Bfs/Search.cs

@@ -0,0 +1,22 @@
+// ReSharper disable once CheckNamespace
+
+namespace aoc.Common.BfsImpl;
+
+public delegate bool Target<in T>(T state); // ITarget?
+
+public static class Targets
+{
+	public static Target<T> Value<T>(T value)
+		=> state => Equals(value, state);
+}
+
+public class SearchFold<T>(Target<T> target) : IFold<T, Result<T>>
+{
+	public (Result<T>, TraversalResult) Fold(Result<T> acc, Path<T> path)
+	{
+		var (current, _) = path.PathList;
+		if (target(current.Item))
+			return (new Found<T>(path), TraversalResult.Interrupt);
+		return (new NotFound<T>(), TraversalResult.Continue);
+	}
+}

src/aoc/Common/L.cs

@@ -10,7 +10,7 @@ public static class L
 	public static L<T> Create<T>(IList<T> values) => L<T>.Create(values);
 } 
 
-public record L<T> : IEnumerable<T> // todo: Equality?
+public record L<T> : IEnumerable<T>
 {
 	private readonly T? value;
 	private readonly L<T>? tail;
@@ -61,6 +61,7 @@ public L<T> Append(L<T> newTail)
 	}
 
 	public T Head => empty ? throw new InvalidOperationException("List is empty") : value!;
+	public L<T>? Tail => tail;
 
 	public bool IsEmpty => empty;
 
@@ -71,4 +72,15 @@ public void Deconstruct(out T head, out L<T>? tail1)
 		tail1 = tail;
 	}
 
+	public virtual bool Equals(L<T>? other)
+	{
+		if (other is null) return false;
+		if (ReferenceEquals(this, other)) return true;
+		return EqualityComparer<T?>.Default.Equals(value, other.value) && Equals(tail, other.tail) && empty == other.empty;
+	}
+
+	public override int GetHashCode()
+	{
+		return HashCode.Combine(value, tail, empty);
+	}
 }