> I had assumed, perhaps wrongly, that the XS mechanism allows Perl to be connected to any compiled language, at least in theory

While I'm not an XS expert -- and further to ++hippo's excellent reply -- I'd put both Java and C# in a separate category due to their reliance on an underlying virtual machine.

I'm not aware of any plans to implement Perl 5 on the JVM (Java) or the CLR (C#). That this would require a huge technical effort is indicated at:

• Re^2: Spoiled by Perl (JVM/CLR)

Update: from the FFI::Platypus docs:

Things not supported include languages that do not compile to machine code ... like .NET based languages and Java

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