;;  ------------------------------------------------------------------------
;; |   FILE           :  utilities.rkt                                      |
;; |   AUTHOR         :  Eugene Wallingford                                 |
;; |   CREATION DATE  :  2025/03/31                                         |
;; |   DESCRIPTION    :  This file contains basic utility functions for     |
;; |                     use in other files.                                |
;;  ------------------------------------------------------------------------

#lang racket
(provide list-of? every?)

;; -------------------------------------------------------------------------
;; (list-of? n) returns a function: a predicate for n-item lists
;; -------------------------------------------------------------------------

(define (list-of? n)
  (lambda (obj)
    (and (list? obj)
         (eq? n (length obj)))))

;; -------------------------------------------------------------------------
;; every? is a predicate that verifies each item in lst passes test?
;; -------------------------------------------------------------------------

(define (every? test? lst)
  (or (null? lst)
      (and (test? (first lst))
           (every? test? (rest lst)))))

;; -------------------------------------------------------------------------