I gave it a shot. The main obstacle for inclusion in Guix is to build the C# libraries. I tried with our Mono 4.4 on SharpZipLib (https://github.com/icsharpcode/SharpZipLib/): --8<---------------cut here---------------start------------->8--- > /gnu/store/fi2i5850527jpw4zbqyw0kaa7yhmrz5w-mono-4.4.1.0/bin/xbuild ICSharpCode.SharpZipLib.csproj XBuild Engine Version 14.0 Mono, Version 4.4.1.0 Copyright (C) 2005-2013 Various Mono authors Build started 1/26/2020 4:53:08 PM. __________________________________________________ ICSharpCode.SharpZipLib.csproj: error : /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format. Build FAILED. Errors: ICSharpCode.SharpZipLib.csproj: error : /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format. 0 Warning(s) 1 Error(s) Time Elapsed 00:00:00.0194670 --8<---------------cut here---------------end--------------->8--- I tried to do what the message says, and then I get: --8<---------------cut here---------------start------------->8--- > /gnu/store/fi2i5850527jpw4zbqyw0kaa7yhmrz5w-mono-4.4.1.0/bin/xbuild ICSharpCode.SharpZipLib.csproj XBuild Engine Version 14.0 Mono, Version 4.4.1.0 Copyright (C) 2005-2013 Various Mono authors Build started 1/26/2020 5:00:19 PM. __________________________________________________ /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: error : /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: The attribute "Version" in element is unrecognized. Build FAILED. Errors: /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: error : /home/ambrevar/projects/SharpZipLib/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj: The attribute "Version" in element is unrecognized. 0 Warning(s) 1 Error(s) Time Elapsed 00:00:00.0222830 --8<---------------cut here---------------end--------------->8--- I guess pkill-9 is right, we need to update Mono first. But maybe we can work around the build system by compiling it manually. I know that the 'mcs' program can compile single-file C# libraries like sdl2-cs. Cheers! -- Pierre Neidhardt https://ambrevar.xyz/