We currently have Mono 4.8 in the ports tree, and Mono 5.2 is available and brings a lot a improvements:
* http://www.mono-project.com/docs/about-mono/releases/5.0.0/
* http://www.mono-project.com/docs/about-mono/releases/5.2.0/
David Naylor (dbn@) has started working on this.
His WIP ports are located in his [GitHub repository](https://github.com/DragonSA/ports) in the [mono-5.2.0.215](https://github.com/DragonSA/ports/tree/mono-5.2.0.215) branch
There is also a [related thread on mono@](https://lists.freebsd.org/pipermail/freebsd-mono/2017-August/002524.html)
TODO:
 * Patch certificates to update mono on update
 * Bump PORTREVISION on all dependent ports of mono
Related bug reports:
 [] Mk/Uses/mono.mk: modernize gac macros (PR 196871)
 [] lang/mono: Update certificates store at install/update time (PR 209670)
 [] lang/mono and net/czmq conflicts with each other due to the same file /usr/local/bin/makecert (PR 223188)
Commit message:
```
Update mono version 5.2.0.215 (and update friends)
Highlights:
 - New Roslyn compiler for C# available
 - devel/msbuild now ported to FreeBSD
 - F# updated to version 4.1.25
 - MonoDevelop updated to version 7.1.0.1297
 - Improved support for nuget packages in USES=mono
USES=mono:
 - properly handle caching of nuget packages
 - add support for multiple feeds for nuget packages
 - add support for nuget dependencies in a separate file
 - add support for paket packages
devel/monodevelop:
 - update to version 7.1.0.1297
 - add azure cli files to the download list
 - remove reference assemblies as a dependency: no longer required
 - remove mono-addins as a dependency: shipped internally (via github)
 - remove cmake as a dependency: replaced by new build system based on msbuild
 - add multiple nuget feeds and move nuget dependencies into separate files
 - explicitly ser full path to install(1) to fix installation script
devel/msbuild: Build platform for .NET and Visual Studio
 - add port for version 15.3.0.0
 - manually implement the dotnet cli (via overridden csc.exe file) to support
   building without having to download .NET Core
lang/mono:
 - update to version 5.2.0.215
 - automate certificate initialisation
 - increase test coverage
lang/fsharp:
 - update to version 4.1.25
 - add msbuild as build dependency (xbuild is no longer used)
 - remove redundant mono dependency (now provided via USES)
x11-toolkits/gnome-sharp20:
 - update to version 2.24.4
 - use github for sources
 - use autoreconf and provided bootstrap script (pre-configure)
x11-toolkits/gtk-sharp20:
 - update to version 2.12.45
```