SQL: using a host variable with the "IN" keyword

I'm trying to format a host variable to support the IN keyword (I'm
using hard-coded IN statements without problem).  The hard-coded
expression would be "...where type in('FL','WA','PA')"; I want to
build the IN keyword predicate dynamically for eventual use in a CASE
statement.

My prototype program has this code:
"Declare Input cursor for select order, state from Orders where state
in :state_list"

It compiles but ti doesn't work

I can built a series of CASE statements to get around this, but I have
one of those feelings (again) that I've overlooked something.

I'd greatly appreciate a working example of using a host variable with
the IN keyword.

Also, is there any way I can view the evaluated SQL statement?  I'm
trying various combinations of things but I'm not getting any SQL
errors; it would be handy to see what SQL is trying to do.

Thanks,
Reeve