varchar vs. text

Is there any way to apply the text functions to a varchar field or
convert from varchar to text? I set up a database with varchar
fields with unspecified sizes because at the time the odbc driver
didn't like to use text as a unique key. Now pg_dump sets the
size as (-5) which won't reload unless I take it out, and I can't
use many of the text-style operators. Using field::text gives:
'ERROR: function text(varchar) does not exist'. Is there any
reason to use varchar now that the ODBC driver works with text,
and is there any way to convert short of pg_dump'ing and editing
the structure?

Les Mikesell
les(at)mcs(dot)com