p9.scm

;;; P9 - Inserción de Strings en Listas

(define compare-lex
  (lambda (a b)
    (string-ci<? (substring a 0 1) (substring b 0 1))))

(define insert
  (lambda (strlst lst)
    (letrec ((combine (lambda (a b)
                        (cond
                          ((null? a) b)
                          ((null? b) a)
                          ((compare-lex (car a) (car b))
                           (cons (car a) (combine (cdr a) b)))
                          (else (cons (car b) (combine a (cdr b)))))))
             (ordered (sort lst compare-lex)))
      (combine strlst ordered))))

;;; Prueba

(print (insert '("Esteban" "Maria") '("Alex" "Maria" "Cristopher" "Roberto" "Esteban")))