UTSL? http://cpansearch.perl.org/src/MSTROUT/Rakudo-Star-2012.08_001/rakudo-star/modules/zavolaj/lib/NativeCall.pm6 has 
# Gets the NCI type code to use based on a given Perl 6 type.
my %type_map =
...
    'Callable' => 'callback';

[download]

so something something perl6 syntax of type Callable :)

perl6 nativecall callable -> http://perlcabal.org/syn/S21.html#Callable_objects

In reply to Re: Help with gtk+ binding for perl6 by Anonymous Monk
in thread Help with gtk+ binding for perl6 by hdias

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