Using Nemerle in asp.net App_Code directory

Question

I want to use Nemerle in an ASP.NET application. Specifically, putting .n files into App_Code.

I added this to my web.config system.codedom/compilers section:

<compiler language="n;Nemerle" extension=".n" type="Nemerle.Compiler.NemerleCodeProvider, Nemerle.Compiler"/>

When running I get this exception:

The assembly '' is already loaded in another appdomain. Setting in machine.config can help solve this issue.

Stack trace

[HttpException (0x80004005): The assembly '' is already loaded in another appdomain. Setting <deployment retail="true" /> in machine.config can help solve this issue.]
   System.Web.Compilation.CodeDirectoryCompiler.GetCodeDirectoryAssembly(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories, Boolean isDirectoryAllowed) +8809675
   System.Web.Compilation.BuildManager.CompileCodeDirectory(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories) +128
   System.Web.Compilation.BuildManager.CompileCodeDirectories() +265
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +320

[HttpException (0x80004005): The assembly '' is already loaded in another appdomain. Setting <deployment retail="true" /> in machine.config can help solve this issue.]
   System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +58
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +512
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +729

[HttpException (0x80004005): The assembly '' is already loaded in another appdomain. Setting <deployment retail="true" /> in machine.config can help solve this issue.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +8890735
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +85
   System.Web.HttpRuntime.ProcessRequestInternal(HttpWorkerRequest wr) +259

What am I doing wrong?

Answer 1

An occasional problem I've found with Visual Studio 2010. Stop any running virtual web server host processes and restart Visual Studio.