Proposal: associative arrays for plpgsql (concept)

Hello
The concept is from Oracle 9i, but with some changes.

http://www.oracle-10g.de/oracle_10g_documentation/appdev.101/b10807/05_colls.htm#i35672

Associative arrays are any arrays with index. Will be created 

DECLARE  x varchar[] INDEX BY VARCHAR = '{}'; -- some format, haven't idea

then I can use anywhere x[key];

two enhancing FOR cycle:
 -- iteration over all values FOR i IN VALUES OF x LOOP -- x array or associative array END LOOP;
 -- iteration over all keys FOR i IN INDICIES OF x LOOP -- x associatice array   x[i] END LOOP;

new functions:

exists(x, key);
delete(x, key);

index is accessable only from PL/pgSQL. Associative arrays can be spec 
PostgreSQL type or clasic arrays with hash index. 

Comments, notes? 

Regards
Pavel Stehule