Looping through cursor row batches

Greetings,

I gather the following isn't possible (which would have been elegant
and ideal):

FOR rec IN
FETCH 100000 FROM cursor
LOOP
...

Anyone know the most efficient way of FETCHing a batch of rows, and
looping through them in a function? FETCHing a record at a time will
work, but I was wondering whether this could be done.

Cheers
Henry