Domains and supporting functions

I've got a domain based on a text type.
I've overridden the equal operator with
lower(text) = lower(text).

I created a table containing my new domain type
and can see that the equals operator is not
being used to determine uniqueness.

What do I need to do to force the UNIQUE constraint
to use the equals function? Is sort going to ignore
the > and < I've defined for this type, too?

Must I create an opclass and create the UNIQUE index
separately from the table creation?
This seems extreme when what I really want to do is to
override the basic comparing functions.

If this is the way domains really are, I would strongly suggest
expanding create domain to merge with create type (under) and
allow us to list the basic functions.

--elein
elein(at)varlena(dot)com

Example;

--
-- check constraint isemail for email base type
--
create or replace function isemail(text) returns boolean as
$$
if ( $_[0] =~ m/^([A-Z0-9]+[._]?){1,}[A-Z0-9]+\@(([A-Z0-9]+[-]?){1,}[A-Z0-9]+\.){1,}[A-Z]{2,4}$/i ) {
return TRUE;
}
else {
return FALSE;
}
$$ language 'plperl';

--
-- create type email under text
--
create domain email as text check ( isemail( value) );

--
-- Equals: lower(text) = lower(text)
--
create or replace function email_eq (email, email) returns boolean as
$$
select case when lower($1) = lower($2) then TRUE else FALSE end;
$$ language 'sql';

create operator = (
PROCEDURE = email_eq,
LEFTARG = email,
RIGHTARG = email
);
create table aliases (
email email UNIQUE PRIMARY KEY,
lname text
);

\echo expect PK ERROR
insert into aliases values ('pk(at)email(dot)com', 'PK');
insert into aliases values ('PK(at)email(dot)com', 'PK');

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