mono-csharp-shell 6.8.0.105+dfsg-1 (amd64 binary) in ubuntu focal

 Mono is a platform for running and developing applications based on the
 ECMA/ISO Standards. Mono is an open source effort led by Xamarin.
 Mono provides a complete CLR (Common Language Runtime) including compiler and
 runtime, which can produce and execute CIL (Common Intermediate Language)
 bytecode (aka assemblies), and a class library.
 .
 This package contains the interactive C# shell named csharp. csharp permits
 dynamically evaluating C# statements, and can be used for writing scripts or
 testing code fragments.
 For examples and a brief overview of the commands see:
 http://www.mono-project.com/CsharpRepl