Index expressions: how to recreate

I noticed the new expression functionality of indices and while
implementing them in pgadmin3 was wonderingnow to extract the definition
from the catalog.

Consider an index that looks like this:

CREATE INDEX foo ON bar (numcol, length(txtcol), intcol2,
length(txtcol2))

Looking at pg_index:

indkey will contain 1 0 4
indclass contains 1988 1978 1978 1978 (numeric, int, int, int)
pg_get_expr(indexprs, indrelid) will deliver (length((txtcol)::text)
AND (length(((txtcol2)::text)))

indclass contains what I'd expect, but indkey shows only 3 columns
and/or expressions.
So I'd recreate the index as being defined as

CREATE INDEX foo ON bar (numcol, (length(txtcol) AND
length(txtcol2)), intcol2)

which obviously isn't correct (and wouldn't execute either, AND with int
operands)

Why is indexprs not a text array containing "", "length(txtcol)", "",
"length(txtcol2)" ?

Regards,
Andreas