You could achieve the desired effect by wrapping a sub around accessing the values of the hash:

my $sr=sub{print shift() . qq(\n)}; # Subref for Hash

my %h=(a=>$sr, b=>$sr);

sub gh{ # Sub to access the hash value and call the sub..
  my $p=shift; # Get the KEY requested
    # In real life, you would first check to see if it was a coderef..
  &{$h{$p}}($p);  # Call the anon sub, passing it the key
  # Returns the result of the call..
}; 

gh($_) for qw(a b b a);

### Prints
a
b
b
a
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