I love this!!!
Very noce - but not limited to the four fiven operands: +-*/
IMHO condition in while loop is pointless because you break after condition in loop is met. You might as well put while(true).
OR put condition in while() and make different set of instructions in loop without break.
Ranges and indices - C# 8.0
OMG, are you a wizard? What is the name of this kind of indexator? I mean s[..i] or [^i..]
C# translation ready! Please review and approve.
You could hardcode with hash maps?
Can you explain how the lack of random tests is a problem here?
Added random tests in C# translation.