db/schema/0012_newtype.sql

create function create_newtype_text(qualified_name text)
  returns void
  language plpgsql
  as $$
begin
  execute concat('create type ', qualified_name, ' as (str text);');
  execute concat( 'create function '
                , qualified_name || '_to_string(val ' || qualified_name || ')'
                , E' returns text language sql as \'select (val.str);\';'
                );
  execute concat( 'create function '
                , qualified_name || '_of_string(val text)'
                , ' returns ' || qualified_name || E' language sql as \'select row(val);\';'
                );
  execute concat( 'create cast '
                , ' (' || qualified_name || ' as text)'
                , ' with function ' || qualified_name || E'_to_string(' || qualified_name || ')'
                , ' as assignment;'
                );
  execute concat( 'create cast '
                , ' (text as ' || qualified_name || ')'
                , ' with function ' || qualified_name || E'_of_string(text)'
                , ' as assignment;'
                );
end;
$$;