Arrays in pgsql

Hallo,
I'm working on a plpgsql-function. I need an array of type integer. The
Programmer's Guide says 'PL/pgSQL variables can have any SQL datatype',
so I'd say there should also be arrays - or am I wrong?

Therefore I've got the following line in my code:

monthday integer[12];

But when running I always get 'ERROR:  parse error at or near "["'. 

Any suggestions?

Martina