CREATE TYPE in Postgres 7.3.4

This is probably really basic, but I can't seem to get it to work. I'm
trying to create an enumerated type, using the following code:

  CREATE FUNCTION enum_gender_in (cstring) RETURNS enum_gender IMMUTABLE AS
    'DECLARE invalue ALIAS FOR $1;
    BEGIN
        IF invalue=''Male'' OR invalue=''0'' THEN RETURN 0; END IF;
        IF invalue=''Female'' OR invalue=''1'' THEN RETURN 1; END IF;
        RAISE EXCEPTION ''Incorrect input value: %'', invalue;
    END;'
  LANGUAGE 'plpgsql';

  CREATE FUNCTION enum_gender_out (enum_gender) RETURNS cstring IMMUTABLE AS
    'DECLARE outvalue ALIAS FOR $1;
    BEGIN
        IF outvalue=0 THEN RETURN ''Male''; END IF;
        IF outvalue=1 THEN RETURN ''Female''; END IF;
        RAISE EXCEPTION ''Incorrect output value: %'', outvalue;
    END;'
  LANGUAGE 'plpgsql';

  CREATE TYPE enum_gender (
    INPUT = enum_gender_in,
    OUTPUT = enum_gender_out,
    INTERNALLENGTH = 2,
    PASSEDBYVALUE
  );

According to the Postgres documentation, when I create the input
function, it should create a placeholder entry in pg_type for
enum_gender and wait for the type to be created. However, when I execute
the CREATE FUNCTION statement, I get:

  ERROR:  Type "enum_gender" does not exist

If I try to create the type first, I get:

  ERROR:  TypeCreate: function enum_gender_in(cstring) does not exist

How do I create this type and these functions?

Alex
--
Mail: Alex Page <alex.page@cancer.org.uk>
Real: Systems/Network Assistant, Epidemiology Unit, Oxford
Tel:  01865 302 223 (external) / 223 (internal)
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