We recently added the C# Interactive REPL from roslyn. However, it doesn't actually work for anything that's not completely trivial:
Microsoft (R) Visual C# Interactive Compiler version 184.108.40.206919
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Type "#help" for more information.
(1,1): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Runtime, Version=220.127.116.11, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
$ mono --version
Mono JIT compiler version 18.104.22.168 (2017-08/e3a2754a33b Tue Aug 22 13:20:37 EDT 2017)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
GC: sgen (concurrent by default)
This looks like some Roslyn issue which I could not track down yet because adding any System.Runtime.dll to the folder with csi.exe makes it work
https://github.com/mono/mono/pull/5737. I'll see if I can come up with a test case for the Roslyn folks
PR was merged
*** Bug 60141 has been marked as a duplicate of this bug. ***