Commas and function-call operators is actually pretty common in Lisp-likes, though they usually still use the symbol instead of some shorthand or initialism, and the opening parens comes before the function name:
(= (> 4 1) true)
I'm not a fan of Copper's local variable syntax though, as the uncle comment by tom_mellior articulated, looks too much like association.
> Local variable access using :? / No commas between parameters? / Operators using function call syntax?
Well, yes, yes and yes.