[tiredandgrumpy]

K is only hard if you try to read it without first studying it. Looping is achieved through adverbs. The key to it is understanding what is a noun (data), verb (operator/function) and adverb (takes a verb, creates a new verb to be used infix). A verb with a noun to its right is a dyad if there is also a noun to its left, and is otherwise a monad. If it is needed, the monad can be specified by appending a colon to the right of the symbol. Fortunately, most kdb+ developers program in Q, which has a bunch of helper routines defined in k, and assigns monads to names such as neg x instead of -:x.