ref: 32172cdf6a00026675dee9be5c0fa3aef5fdff9d
dir: femtolisp/tests/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)))