ref: a4bb09bcb2389b3d6f1cb1a2bc5b344eff6ccecb
dir: /femtolisp/pisum.lsp/
(defun pisum ()
(dotimes (j 500)
((label sumloop
(lambda (i sum)
(if (> i 10000)
sum
(sumloop (+ i 1) (+ sum (/ (* i i)))))))
1.0 0.0)))