range.lisp

(cl:in-package #:incf-cl)

;;; Copyright (c) 2007-2019 Juan M. Bello Rivas <jmbr@superadditive.com>
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;;; Miscellaneous functions to build ranges of numbers (vaguely
;;; resembling MATLAB's vector notation).

(defun range (a b &optional c)
  ;; This could be implemented using unfold too but we do it this way
  ;; for efficiency.
  (flet ((aux (start step stop)
           (assert (and (<= start stop) (> step 0)))
           (loop for x from start to stop by step collect x)))
    (if c
        (aux a b c)
        (aux a 1 b))))