KDB/Q: how to loop without loops?

I am learning q on kdb database. I am concerned by the fact that there are no loops in q. I need to write an algorithm that I would write with several nested for-loops in a verbose program like C. But in q I am stuck by the fact that I cannot loop.

Just to give a specific example (one of many), I have this simple vector (column table):

q)closures
price
-----
18.54
18.53
18.53
18.52
18.57
18.9 
18.9 
18.77
18.59
18.51
18.37

I need a vector that groups 3by3 these entries, with superposition, like (using R syntax): closures[0:2],closures[1:3],closures[2:4],closures[3:5]... How can I do?

In general, how do I need to change my mentality, to correctly program in q?

Thanks a lot for your suggestions Marco