added noise

2 files changed, 12 insertions, 0 deletions

diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp
index a0e74e7..35b834c 100644
--- a/gtwiwtg.lisp
+++ b/gtwiwtg.lisp
@@ -82,6 +82,17 @@ the values passed as ARGS looped forever."
                                 (values (car state) (cdr state))
                                 (values (car args) (copy-list (cdr args)))))))
 
+
+(defun noise (&optional (arg 1.0))
+  "Creates a generator that produces an infinite series of random
+  numbers that are the result of calling (RANDOM ARG)."
+  (make-instance 'generator!
+                 :state nil
+                 :next-p-fn (constantly t)
+                 :next-fn (lambda (state)
+                            (declare (ignore state))
+                            (values (random arg) nil))))
+
 ;;; Some utilities
 
 (defun all-different (things)
diff --git a/package.lisp b/package.lisp
index 6f853bd..40452be 100644
--- a/package.lisp
+++ b/package.lisp
@@ -6,6 +6,7 @@
            #:times
            #:seq
            #:repeater
+           #:noise
            #:yield-to!
            #:map!
            #:filter!