Mono

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From Wikipedia:

Mono is a [...] project to create a .NET Framework-compatible set of tools including, among others, a C# compiler and a Common Language Runtime.

Installation

Install the mono package.

If you need VisualBasic.Net support you have to install the VisualBasic.Net interpreter with the package mono-basicAUR.

MonoDevelop calls xterm when you run your project. You might install it, when you are writing a console application.

Note: Installing the package stores certificate authorities in /usr/share/.mono/certs/Trust/ but removing the package does not remove them.[1]

Running Mono applications

You can execute Mono binaries by calling mono manually: 

$ mono programsname.exe

You can also execute Mono binaries directly, just like native binaries: 

$ chmod 755 exefile.exe
$ ./exefile.exe

Testing Mono

Make a new file: 

test.cs
using System;

public class Test {
 public static void Main(string[] args) {
  Console.WriteLine("Hello World!");
 }
}

Then run: 

$ mcs test.cs
$ mono test.exe
Hello world!

Development

Starting to develop in Mono/C# is very easy. Just install the MonoDevelop IDE with package monodevelop-stableAUR[broken link: package not found] or monodevelop-gitAUR[broken link: package not found]. Alternatively, you can install the riderAUR IDE.

If you want the API documentation browser and some testing and development tools you have to install mono-tools.

Troubleshooting

I get an error "cannot execute "path/to/your/binary" file name has not been set."

You might install xterm, since MonoDevelop starts xterm when you press on run. This might be a possible dependency.

I get an error when I try to run Mono binaries directly: "cannot execute binary file"

The binfmt_misc handler for Mono has not yet been set up, as explained in detail on the Mono Project website.

To fix this, restart the systemd-binfmt service.

I get an TLS handshake (or similar certificate based) error

Try mozroots --import --ask-remove which should update monos certificates. mozroots is part of the mono package.

I get an error when building fsharp: "System.TypeInitializationException: The type initializer for 'System.Console' threw an exception"

There is a recent bug in mcs that is used to build fsharp. A workaround is to use export TERM=xterm, as detailed here [2]

See also