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Adrian
Adrian

Reputation: 879

How to map a function in Common Lisp?

I made this function in Common Lisp

(defun f (&key n p x)
    (* (combinacion n x) (expt p x) (expt (- 1 p) (- n x))))

and it works fine. The thing is that I want to make a function in Common Lisp lake the following Haskell function

ff n p x = sum . map (f n p) $ [0 .. x]

namley, map the function f partially applied to a list.

I made the following function to create the lists

(defun range (&key max (min 0) (step 1))
    (loop for n from min to max by step
        collect n))

and works fine too, I only need to know how to make the mapping.

Upvotes: 2

Views: 1258

Answers (1)

Barmar
Barmar

Reputation: 781310

Common Lisp doesn't have partial applications built in, you just have to write a lambda expression to do what you want.

(defun map-f (n p limit)
  (let ((x-list (range :max limit)))
    (mapcar #'(lambda (x) (f :n n :p p :x x)) x-list)))

Upvotes: 7

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