The word prefix is still throwing me. I think a better term would be predicate.

I personally believe that it won't and I can't understand why it's throwing you, given that it's the correct technical term. In Perl 6 you can actually declare prefix, postfix, circumfix, etc. operators, which are basically regular functions.

Again, the notation you propose would be ambiguous.

It was just a very wild shot at it, to explain the kind of beast I "want," not a possible description of the beast. Actually I pointed out it couldn't be, for a well defined reason. That's why I'm asking here.

In your example: my $href = \% <== foo => 1, bar => 2; That could either mean a hash whose first key is a hashref 'foo' or a reference to a hash with one key 'foo' followed by the comma operator and a two element list ( bar, '2' ). Although in the case provided it may be clear what you intended, the ambiguity increases if one were to attempt to nest operators:

I call that an ordinary precedence issue, (except that I didn't specify the precedence of the operator nor do I have any precise idea about it) to be resolved with the use of parens when not doing the right thing without them.