Discussion on: Challenge: find 'Kaprekar numbers'

[WammKD]

For those a fan of Guile:

(use-modules (srfi srfi-1))

(let find-kaprekars ([kaprekars '()] [currNum 1])
  (if (= (length kaprekars) 8)
      (reverse kaprekars)
    (if (let ([cnStr (string-append "0" (number->string (expt currNum 2)))])
          (any
            (lambda (index)
              (let ([scndPart (string->number (substring cnStr index))])
                (if (zero? scndPart)
                    #f
                  (=
                    (+ (string->number (substring cnStr 0 index)) scndPart)
                    currNum))))
            (iota (1- (string-length cnStr)) 1)))
        (find-kaprekars (cons currNum kaprekars) (1+ currNum))
      (find-kaprekars kaprekars (1+ currNum)))))