You certainly have a good point from a parsing perspective, and this is likely where most of the implementation issues arise. Still, this limitation is really not all that different from the way Perl treats $AUTOLOAD type function calls. You have to be careful to adjoin the function name with brackets, because the compiler isn't astute enough to find the function reference, instead assuming there is a bare word in your code, and whining accordingly. Here's how the compiler appears to behave when finding functions to AUTOLOAD:

     Func($x)        -> &Func($x)  OK
     Func ($x)       -> 'Func' ($x)   !?!?
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So, presumably, the same thing would apply to the parsing of curly braces, in theory:

     foo $bar{$baz}  -> &foo($bar{$baz})
     foo $bar {$baz} -> &foo($bar,sub {$baz})
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I discovered this trying to eliminate the requirement for 'my ($self) = @_' having to be in every function for an OO program by writing a wrapper which did it for you. For whatever reason, you can't operate on a named sub. Oh well.