diff --git a/Sanchime.Functional/Core/Extensions/Nullable.cs b/Sanchime.Functional/Core/Extensions/Nullable.cs
new file mode 100644
index 0000000..c07d35c
--- /dev/null
+++ b/Sanchime.Functional/Core/Extensions/Nullable.cs
@@ -0,0 +1,12 @@
+using Sanchime.Functional.Core.Products;
+
+namespace Sanchime.Functional.Core.Extensions;
+
+public static class NullableExtension
+{
+    /// <summary>
+    /// 将<see cref="Nullable"/>值转换为<see cref="Option"/>
+    /// </summary>
+    public static Option<T> ToOption<T>(this Nullable<T> @this) where T : struct
+        => @this.HasValue ? Option.Some(@this.Value) : Option.None;
+}
diff --git a/Sanchime.Functional/Core/Products/IApplicative.cs b/Sanchime.Functional/Core/Products/IApplicative.cs
new file mode 100644
index 0000000..e46f4e1
--- /dev/null
+++ b/Sanchime.Functional/Core/Products/IApplicative.cs
@@ -0,0 +1,9 @@
+namespace Sanchime.Functional.Core.Products;
+
+/// <summary>
+/// 应用函子
+/// </summary>
+/// <typeparam name="TCategory"></typeparam>
+public interface IApplicative<TCategory> : IFunctor<TCategory>
+{
+}
diff --git a/Sanchime.Functional/Core/Products/IFunctor.cs b/Sanchime.Functional/Core/Products/IFunctor.cs
index 1b81561..4fc6a57 100644
--- a/Sanchime.Functional/Core/Products/IFunctor.cs
+++ b/Sanchime.Functional/Core/Products/IFunctor.cs
@@ -7,5 +7,15 @@ namespace Sanchime.Functional.Core.Products;
 /// <typeparam name="TCategory"></typeparam>
 public interface IFunctor<TCategory> : ICategory
 {
-    IFunctor<TResult> Map<TResult>(Func<TCategory, IFunctor<TResult>> mapping);
+    TCategory Map(Func<TCategory, TCategory> mapping);
+}
+
+
+public struct Test<T> : IFunctor<Test<T>>
+{
+    public T? Value {get; set; }
+    public Test<T> Map(Func<Test<T>, Test<T>> mapping)
+    {
+        return mapping(this);
+    }
 }
diff --git a/Sanchime.Functional/Core/Products/IMonad.cs b/Sanchime.Functional/Core/Products/IMonad.cs
new file mode 100644
index 0000000..47fbd56
--- /dev/null
+++ b/Sanchime.Functional/Core/Products/IMonad.cs
@@ -0,0 +1,9 @@
+namespace Sanchime.Functional.Core.Products;
+
+/// <summary>
+/// 单子
+/// </summary>
+/// <typeparam name="TCategory"></typeparam>
+public interface IMonad<TCategory> : IApplicative<TCategory>
+{
+}
diff --git a/Sanchime.sln b/Sanchime.sln
index fecf226..7052d2a 100644
--- a/Sanchime.sln
+++ b/Sanchime.sln
@@ -7,6 +7,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Sanchime.Test", "Sanchime.T
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Sanchime.Functional", "Sanchime.Functional\Sanchime.Functional.csproj", "{DF48AFE2-CD1B-4BCE-83EF-DA8BDA104069}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Sanchime.Toolkits", "Sanchime.Toolkits\Sanchime.Toolkits.csproj", "{3A94EB2F-04F1-46F8-ADD8-DE091402635F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -24,5 +26,9 @@ Global
 		{DF48AFE2-CD1B-4BCE-83EF-DA8BDA104069}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{DF48AFE2-CD1B-4BCE-83EF-DA8BDA104069}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{DF48AFE2-CD1B-4BCE-83EF-DA8BDA104069}.Release|Any CPU.Build.0 = Release|Any CPU
+		{3A94EB2F-04F1-46F8-ADD8-DE091402635F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{3A94EB2F-04F1-46F8-ADD8-DE091402635F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{3A94EB2F-04F1-46F8-ADD8-DE091402635F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{3A94EB2F-04F1-46F8-ADD8-DE091402635F}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal