How do I create an array?

I'm trying to create a function that operates on integer[]. It works great if
I have an integer[] column already in the table. However I don't see how to
create an array dynamically given two integers.

I could paste together a string representation and then cast it back using
something like ('{'||a||','||b||'}')::integer[] but that seems terribly
wasteful. And it doesn't seem to work anyways.

There must be something like the point() function for arrays, no? I'm probably
missing something obvious or looking in the wrong place? I just don't see it.

--
greg