I had some fun printing prime factors of things.

diff --git a/doc/examples/factor.pez b/doc/examples/factor.pez
new file mode 100644 (file)
index 0000000..c0f63c5
--- /dev/null
+++ b/doc/examples/factor.pez
@@ -0,0 +1,30 @@
+#! /usr/bin/env pez
+# Illustrative!  This little program is a roughly compatible version of the Unix
+# command 'factor', which, given 1 or more positive integer arguments on the
+# command-line, will print each argument, followed by a colon and a
+# space-separated list of factors.
+
+# Yes, also, it uses the second-dumbest possible algorithm.
+
+: print-factors ( n -- )
+       dup "%ld: " format print
+       begin dup 2 mod 0= while 2 . 2 / repeat
+       3
+       begin over 1 > while
+               2dup /mod swap ( n m n/m n%m )
+               0= if over . -rot nip
+               else drop 2 + then
+       repeat cr 2drop ;
+
+: factor-args
+       argc 0= if exit then
+       argc 0 do
+               argv i cells + @ strint nip ( arg )
+               dup 0 < if negate print-factors
+                       else dup 2 <
+                               if dup "%ld: " format print . cr
+                               else print-factors then
+                       then 
+       loop ;
+
+factor-args