OK, thanks. I may have been thinking along the lines of:

has x => (..., default => 'abc');
has y => (..., default => sub { [qw{a b c}] });
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where that second line can't be written as:

has y => (..., default => [qw{a b c}]);
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But, of course, in the constructor you use the values as is (without needing a coderef):

...->new(x => 'def', y => [qw{d e f}]);
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