Not the parent, but I personally don't like prefix syntax for such common operators. As for the colons combined with the absence of commas, this suggests keyword syntax to me. I.e., as if the gte function took one argument named a. Like this Python call:
Actually, it can take multiple. gte(a: b: c: d:) is equivalent to (in C) a >= b && a >= c && a >= d. By making operators like functions, you can group like-operations and simplify code. Admittedly, it's not as readable for someone accustomed to seeing C style.
Last note: gte(a=100) would produce an error in Copper because a=100 is an assignment statement that returns "a" (a function), and gte( function ) means nothing.
Edit: I see you're referring to Python, but I figured I'd keep the note of comparison.
