ref: 2ddbac400ae15e6f5a1de84a9fe0646f9cd1944c
dir: /femtolisp/pisum.lsp/
(define (pisum)
(dotimes (j 500)
((label sumloop
(lambda (i sum)
(if (> i 10000)
sum
(sumloop (+ i 1) (+ sum (/ (* i i)))))))
1.0 0.0)))