I'm an ass.

pascal.hs

pascal' :: [Int] -> [Int]
pascal' l
    | length l < 2 = [1]
    | otherwise = (a + b) : (pascal' (b:rest))
    where a:(b:rest) = l

pascal :: [Int] -> [Int]
pascal = (1:) . pascal'

pascal.lsp

(defun pascal% (list)
  (if (<= (length list) 1)
    list
    (cons (+ (first list) (second list)) (pascal% (cdr list)))))

(defun pascal (prev)
  (if (not prev)
    '(1)
    (cons 1 (pascal% prev))))