Here's a working version of your code, chuck_masta_grep added by zilti on Thu Oct 1 23:47:28 2020

(import (chicken io) (chicken string) (chicken format))
(define (suminput running)
        (let ((line (read-line)))
                (if (< 0 (string-length line))
                        (suminput (+ running (string->number line)))
                        running)))
(format #t "sum of inputs was: ~A~%" (suminput 0))