plpgsql array initialization, what's the story?

Postgresql 8.0.1

If I write the plpgsql:

declare
y int[];
begin
y[1] := 1;
y[2] := 2;
y[3] := 3;
...

All y[] array elements are NULL, as is array_dims(y).
But if I write:

declare
y int[] := '{}';
begin
y[1] := 1;
y[2] := 2;
y[3] := 3;
...

Then things work as expected.

What's going on? (As in "Gosh, it looks like something's
happening here that I should know about.")

This behavior is not clear from the plpgsql documentation.

Regards,

Karl <kop(at)meme(dot)com>
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