A simple C# implementation of Siren.

siren.cs

public class Siren
{
	public readonly string Title;
	public readonly IEnumerable<string> Class;
	public readonly IDictionary<string, string> Properties;
	public readonly IEnumerable<Entity> Entities;
	public readonly IEnumerable<Action> Actions;

	public Siren(
		string title = null, 
		IEnumerable<string> @class = null, 
		IDictionary<string, string> properties = null, 
		IEnumerable<Entity> entities = null, 
		IEnumerable<Action> actions = null
	)
	{
		Title = title;
		Class = @class;
		Properties = properties;
		Entities = entities;
		Actions = actions;
	}

	public class Entity
	{
		public readonly IEnumerable<string> Rel;

		public Entity(IEnumerable<string> rel = null)
		{
			Rel = rel;
		}
	}

	public class EntityLink : Entity
	{
		public readonly IEnumerable<string> Class;
		public readonly string Href;

		public EntityLink(string href, IEnumerable<string> rel, IEnumerable<string> @class = null)
			: base(rel)
		{
			Href = href;
			Class = @class;
		}
	}

	public class EntityRepresentation<T> : Entity
	{
		public readonly T Entity;

		public EntityRepresentation(IEnumerable<string> rel, T entity)
			: base(rel)
		{
			Entity = entity;
		}
	}
	
	public class Link
	{
		public readonly string Href;
		public readonly IEnumerable<string> Rel;

		public Link(string href, IEnumerable<string> rel)
		{
			Href = href;
			Rel = rel;
		}
	}

	public class Action
	{
		public readonly string Name;
		public readonly IEnumerable<string> Class;
		public readonly string Method;
		public readonly string Href;
		public readonly string Title;
		public readonly string Type;
		public readonly IEnumerable<Field> Fields;

		public Action(string name, string href, IEnumerable<string> @class = null, string method = null, string title = null, string type = null, IEnumerable<Field> fields = null)
		{
			Name = name;
			Href = href;
			Class = @class;
			Method = method;
			Title = title;
			Type = type;
			Fields = fields;
		}
	}

	public class Field
	{
		public readonly string Name;
		public readonly string Type;
		public readonly string Value;

		public Field(string name, string type = "text", string value = null)
		{
			Name = name;
			Type = type;
			Value = value;
		}
	}
}