If you try to run:

use strict;
use warnings;

sub proto ($&);

proto 1, {};
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you get the error message:

Type of arg 2 to main::proto must be sub {} (not anonymous hash ({})) 
+at noname2.pl line 7, near ";}"
Execution of noname2.pl aborted due to compilation errors.
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Kinda says it all really doesn't it?

Note that what is hard for the compiler to make sense of is often harder for people to interpret correctly. Taking away information like "This is a sub" can make it very hard to maintain code. In general don't use prototypes!

Golfing code to reduce key strokes is almost always counter productive in terms of getting a job done.