Sum a list without recursion/looping in Scheme/Racket

I'm working on an assignment involving Racket and I was hoping somebody could lead me into the right direction.

I must calculate the norm of a list without recursion or using a loop and without defining any helper functions.

Is this possible? The only thing that comes to mind is to someh开发者_开发知识库ow use the built-in map functions

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(define (norm lst)
  (apply + (map square lst)))