Let me continue by pointing out that in Perl 6 you would not write max as a list operator or function. Rather, write it as an infix (2-argument) function, and the system will automatically generate the matching reduction operator. Or, write the reduction operator yourself if that's more efficient, but use the reduction syntax:

sub infix:<max> (::Type $left, Type $right --> Type)
 {
   return $left after $right ?? $left !! $right;
 }

sub prefix:<[max]> (::Type *$first, Type *@rest --> Type) { ... }
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That leaves off the details of how to make it a chaining operator (I guess max chains through normal association) and declaring its level of precedence and associativity, etc.