Added sorting-routines

README.md

@@ -111,10 +111,11 @@ Here the regular expressions will be matched against the name of the file(s) in
 
 A reasonable amount of sample code can be found in the various included examples:
 
-* [test.lisp](test.lisp) shows many things.
 * [fibonacci.list](fibonacci.lisp) calculate the first 25 numbers of the Fibonacci sequence.
 * [fizzbuzz.lisp](fizzbuzz.lisp) is a standalone sample of solving the fizzbuzz problem.
 * [mtest.lisp](mtest.lisp) shows some macro examples.
+* [sorting.lisp](sorting.lisp) demonstrates writing & benchmarking sorting-routines.
+* [test.lisp](test.lisp) shows many things.
 
 As noted there is a standard-library of functions which are loaded along with any user-supplied script - that library of functions may also provide a useful reference and example of yal-code:
 

sorting.lisp

@@ -0,0 +1,124 @@
+;;; sorting.lisp - Demonstrate generating random lists, and sorting them.
+
+;;
+;; This example demonstrates creating lists of random (integer)
+;; numbers, and sorting them with two different methods.
+;;
+;; Our random numbers range from -1024 to +1024.
+;;
+;; We have three sorting methods to test:
+;;
+;;  1.  insert-sort, implemented in lisp.
+;;
+;;  2.  quick-sort, implemented in lisp.
+;;
+;;  3.  sort, implemented in golang
+;;
+
+
+(set! random:number (fn* ()
+                         "Return a random number from -1024 to 1024"
+                         (let* (sign 1
+                                max  1024)
+                           ; optionally this might be negative
+                           (if (= 0 (random 2))
+                               (set! sign -1))
+                           (* sign (random max)))))
+
+(set! random:list (fn* (n)
+                       "Return a random list of numbers, of the length n."
+                       (map (seq n) random:number)))
+
+
+
+;;
+;; insertion-sort
+;;
+
+(set! insert (fn* (item lst)
+                  (if (nil? lst)
+                      (cons item lst)
+                    (if (> item (car lst))
+                        (cons (car lst) (insert item (cdr lst)))
+                      (cons item lst)))))
+
+(set! insertsort (fn* (lst)
+                      (if (nil? lst)
+                          nil
+                        (insert (car lst) (insertsort (cdr lst))))))
+
+
+
+
+;;
+;; quick-sort
+;;
+
+;; append in our standard library makes "(list b)" not "b".  Changing that
+;; would cause issues, so I'm duplicating here.
+(set! append2 (fn* (a b)
+                  (if (nil? a)
+                      b
+                    (cons (car a) (append2 (cdr a) b) ))))
+
+(set! append3 (fn* (a b c)
+                   (append2 a (append2 b c))))
+
+(set! list>= (fn* (m list)
+                  (filter list (lambda (n) (! (< n m))))))
+
+(set! list< (fn* (m list)
+                 (filter list (lambda (n) (< n m)))))
+
+(set! qsort (fn* (l)
+                 (if (nil? l)
+                     nil
+                   (append3 (qsort (list< (car l) (cdr l)))
+                            (cons (car l) null)
+                            (qsort (list>= (car l) (cdr l)))))))
+
+
+
+
+;;
+;; Now we have defined functions to generate a list of random integers,
+;; and we also have our two sorting methods, so we can test things :)
+;;
+;; Spoiler qsort is the faster lisp sort, but the native golang sort
+;; is significantly faster - due to lack of recursion & etc.
+;;
+(let* (
+       lst (random:list 512)       ; create a random list - 512 elements
+
+           bis (ms)                ; before-insert-sort take a timestamp
+           isrt (insertsort lst)   ;   run insert-sort
+           ais (ms)                ; after insert-sort take a timestamp
+
+           bqs (ms)                ; before-quick-sort take a timestamp
+           qsrt (qsort lst)        ;   run the quick-sort
+           aqs (ms)                ; after-quick-sort take a timestamp
+
+           bgs (ms)                ; before-go-sort take a timestamp
+           gsrt (sort lst)         ;   run the go sort
+           ags (ms)                ; after-go-sort take a timestamp
+       )
+  (print "insert sort took %d ms " (- ais bis))
+  (print "quick sort took %d ms " (- aqs bqs))
+  (print "go sort took %d ms " (- ags bgs))
+
+  ; a simple sanity-check of the results
+  (print "Testing results - first 20 - to make sure all sorts were equal")
+  (print "insert-sort,quick-sort,go-sort")
+  (apply (nat 20)
+         (lambda (x)
+           (let* (a (nth isrt x)
+                  b (nth qsrt x)
+                  c (nth gsrt x))
+
+                  (if (! (eq a b))
+                      (print "List element %d differs!" x))
+                  (if (! (eq b c))
+                      (print "List element %d differs!" x))
+                  (print "%d,%d,%d" a b c))))
+  (print "All done!")
+  )