TypeInitializationException F# snippets (#8017)

Author: albert-du

snippets/fsharp/System/TypeInitializationException/Overview/Missing1.fs

@@ -0,0 +1,27 @@
+module Missing1
+
+open Missing1a
+// <Snippet2>
+open System
+
+type Person(fName, lName) =
+    static let infoModule = InfoModule DateTime.UtcNow
+    
+    do infoModule.Increment() |> ignore
+   
+    override _.ToString() =
+        $"{fName} {lName}"
+let p = Person("John", "Doe")
+
+printfn $"{p}"
+// The example displays the following output if missing1a.dll is renamed or removed:
+//    Unhandled Exception: System.TypeInitializationException: 
+//       The type initializer for 'Person' threw an exception. ---> 
+//       System.IO.FileNotFoundException: Could not load file or assembly 
+//       'Missing1a, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' 
+//       or one of its dependencies. The system cannot find the file specified.
+//       at Person..cctor()
+//       --- End of inner exception stack trace ---
+//       at Person..ctor(String fName, String lName)
+//       at Example.Main()
+// </Snippet2>

snippets/fsharp/System/TypeInitializationException/Overview/Missing1a.fs

@@ -0,0 +1,15 @@
+module Missing1a
+
+// <Snippet1>
+open System
+
+type InfoModule(firstUse: DateTime) =
+    let mutable ctr = 0
+
+    member _.Increment() =
+        ctr <- ctr + 1
+        ctr
+   
+    member _.GetInitializationTime() =
+        firstUse
+// </Snippet1>

snippets/fsharp/System/TypeInitializationException/Overview/Regex1.fs

@@ -0,0 +1,23 @@
+// <Snippet4>
+open System
+open System.Text.RegularExpressions
+
+let domain = AppDomain.CurrentDomain
+// Set a timeout interval of -2 seconds.
+domain.SetData("REGEX_DEFAULT_MATCH_TIMEOUT", TimeSpan.FromSeconds -2)
+
+let rgx = Regex "[aeiouy]"
+printfn $"Regular expression pattern: {rgx}"
+printfn $"Timeout interval for this regex: {rgx.MatchTimeout.TotalSeconds} seconds"
+// The example displays the following output:
+//    Unhandled Exception: System.TypeInitializationException: 
+//       The type initializer for 'System.Text.RegularExpressions.Regex' threw an exception. ---> 
+//       System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
+//       Parameter name: AppDomain data 'REGEX_DEFAULT_MATCH_TIMEOUT' contains an invalid value or 
+//       object for specifying a default matching timeout for System.Text.RegularExpressions.Regex.
+//       at System.Text.RegularExpressions.Regex.InitDefaultMatchTimeout()
+//       at System.Text.RegularExpressions.Regex..cctor()
+//       --- End of inner exception stack trace ---
+//       at System.Text.RegularExpressions.Regex..ctor(String pattern)
+//       at Example.Main()
+// </Snippet4>

snippets/fsharp/System/TypeInitializationException/Overview/fs.fsproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Missing1a.fs" />
+    <Compile Include="Missing1.fs" />
+    <Compile Include="Regex1.fs" />
+  </ItemGroup>
+</Project>

xml/System/TypeInitializationException.xml

@@ -80,7 +80,7 @@
 <a name="Static"></a>   
 ## Static constructors and the TypeInitializationException
 
- A static constructor, if one exists, is called automatically by the runtime before creating a new instance of a type. Static constructors can be explicitly defined by a developer. If a static  constructor is not explicitly defined, compilers automatically create one to initialize any `static` (in C#) or `Shared` (in Visual Basic) members of the type.  For more information on static constructors, see [Static Constructors](/dotnet/csharp/programming-guide/classes-and-structs/static-constructors).  
+ A static constructor, if one exists, is called automatically by the runtime before creating a new instance of a type. Static constructors can be explicitly defined by a developer. If a static  constructor is not explicitly defined, compilers automatically create one to initialize any `static` (in C# or F#) or `Shared` (in Visual Basic) members of the type.  For more information on static constructors, see [Static Constructors](/dotnet/csharp/programming-guide/classes-and-structs/static-constructors).  
   
  Most commonly, a <xref:System.TypeInitializationException> exception is thrown when a static constructor is unable to instantiate a type.  The <xref:System.Exception.InnerException%2A> property indicates why the static constructor was unable to instantiate the type. Some of the more common causes of a <xref:System.TypeInitializationException> exception are:  
   
@@ -92,7 +92,7 @@
   
    -   It has been explicitly defined as a member of a type.  
   
-   -   The type has  `static` (in C#) or `Shared` (in Visual Basic) variables that are declared and initialized in a single statement. In this case, the language compiler generates a static constructor for the type. You can inspect it by using a utility such as [IL Disassembler](/dotnet/framework/tools/ildasm-exe-il-disassembler). For instance, when the C# and VB compilers compile the following example, they generate the IL for a static constructor that is similar to this:  
+   -   The type has  `static` (in C# or F#) or `Shared` (in Visual Basic) variables that are declared and initialized in a single statement. In this case, the language compiler generates a static constructor for the type. You can inspect it by using a utility such as [IL Disassembler](/dotnet/framework/tools/ildasm-exe-il-disassembler). For instance, when the C# and VB compilers compile the following example, they generate the IL for a static constructor that is similar to this:  
   
    ```  
    .method private specialname rtspecialname static   
@@ -121,12 +121,17 @@
    ```csharp  
    csc -t:library Missing1a.cs  
    ```  
+
+   ```fsharp  
+   fsc --target:library Missing1a.fs  
+   ```  
   
    ```vb  
    vbc Missing1a.vb -t:library  
    ```  
   
    :::code language="csharp" source="~/snippets/csharp/System/TypeInitializationException/Overview/Missing1a.cs" id="Snippet1":::
+   :::code language="fsharp" source="~/snippets/fsharp/System/TypeInitializationException/Overview/Missing1a.fs" id="Snippet1":::
    :::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/System.TypeInitializationException/vb/Missing1a.vb" id="Snippet1":::  
   
    You can then compile the following example to an executable named Missing1.exe by including a reference to Missing1a.dll:  
@@ -142,6 +147,7 @@
    However, if you rename, move, or delete Missing1a.dll and run the example, it throws a <xref:System.TypeInitializationException> exception and displays the output shown in the example.  Note that the exception message includes information about the <xref:System.Exception.InnerException%2A> property. In this case,  the inner exception is a <xref:System.IO.FileNotFoundException> that is thrown because the runtime cannot find the dependent assembly.  
   
    :::code language="csharp" source="~/snippets/csharp/System/TypeInitializationException/Overview/Missing1.cs" id="Snippet2":::
+   :::code language="fsharp" source="~/snippets/fsharp/System/TypeInitializationException/Overview/Missing1.fs" id="Snippet2":::
    :::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/System.TypeInitializationException/vb/Missing1.vb" id="Snippet2":::  
   
    > [!NOTE]
@@ -154,6 +160,7 @@
  The following example shows the <xref:System.TypeInitializationException> that is thrown when the value assigned to the "REGEX_DEFAULT_MATCH_TIMEOUT" property is invalid. To eliminate the exception, set the"REGEX_DEFAULT_MATCH_TIMEOUT" property to a  <xref:System.TimeSpan> value that is greater than zero and less than approximately 24 days.  
   
  :::code language="csharp" source="~/snippets/csharp/System/TypeInitializationException/Overview/Regex1.cs" id="Snippet4":::
+ :::code language="fsharp" source="~/snippets/fsharp/System/TypeInitializationException/Overview/Regex1.fs" id="Snippet4":::
  :::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/System.TypeInitializationException/vb/Regex1.vb" id="Snippet4":::  
   
 <a name="Calendars"></a>