diff options
| -rw-r--r-- | gtwiwtg.lisp | 35 |
1 files changed, 30 insertions, 5 deletions
diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp index 88e820c..9c50877 100644 --- a/gtwiwtg.lisp +++ b/gtwiwtg.lisp @@ -41,12 +41,37 @@ ;;; CONSTRUCTORS -(defun range (&key (from 0) to (by 1)) +(defun range (&key (from 0) to (by 1) inclusive) "Create a generator that produces a series of numbers between FROM -and TO, inclusive, with step size of BY. +and TO with step size of BY. -If TO is NIL, then the generator produces an infinite sequence." - (let ((comparator (if (plusp by) #'< #'>))) +When INCLUSIVE is non NIL, then TO will be produced by the generator +if it would be the last member of generate series. + +E.g. + +> (collect (range :to 10)) + + (0 1 2 3 4 5 6 7 8 9) + +> (collect (range :to 10 :inclusive t)) + + (0 1 2 3 4 5 6 7 8 9 10) + +> (collect (range :to 10 :by 2 :inclusive t)) + + (0 2 4 6 8 10) + +> (collect (range :to 10 :by 3 :inclusive t)) + + (0 3 6 9) + +If TO is NIL, then the generator produces an infinite sequence. + +" + (let ((comparator (if (plusp by) + (if inclusive #'<= #'<) + (if inclusive #'>= #'>)))) (make-instance 'generator! :state (list (- from by) to) :next-p-fn (lambda (state) (or (not to) @@ -435,7 +460,7 @@ also be sorted according to COMPARATOR. The generator created through a merge has a length that is maximal among the lengths of the arguments to MERGE!. Hence, if any of the -arguments is an infinite generator, then the merged generator is also +arguments is an infinite generator, then the new generator is also infinite. An example: |