In learning C#, I was (among other things) annoyed at having to write 
Dog skip = new Dog();

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while in C++, 
Dog skip;

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is sufficient. But before getting very far, I realized that in Perl we have to call new (or whatever) on everything, too. Ah, but the type is still named only once: 
my $skip= Dog->new;

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since the variable is not typed.

So, if Perl 6 is going to have much stronger compile-time awareness of types, perhaps we should have (to use the familiar Perl 5 syntax) 

my Dog $skip;
$skip->bark;

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work properly.

How?

My first thought was to have a typed variable autovivify to a reference of the proper type. So, since bark() is called on undef, it creates one first. Assigning a value to $skip at any point before its used would suppress that behavior.

We already autovivify undef's based on how they are used: $x->[$y] will create an array ref, and we don't hear any cries from users about "well, maybe we wanted it to be undefined to indicate an error!" as in $x= find_my_array(); $x->[$y]; so extending this to members should not be any different conceptually. If you want to allow undef to mean an exception, check for it!

Another idea is to have a typed variable use a default initializer if one is not specified in the statement. So, 

my Dog $skip;

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would, as part of the "my" processing, call Dog->CREATE or somesuch. If you really wanted my Dog $skip= undef; you could say so.

—John

In reply to Fun with Typed Objects 1 by John M. Dlugosz

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