add examples

README.md

@@ -7,3 +7,35 @@ the language it's interpreting.  PARSE/WORD and the input stream
 handling was the first place this became obvious.  This design is a
 dead end.  The path forward would be stripping it back to primitives
 and rewriting the outer interpreter in Forth.
+
+Here are things it can do today:
+
+Print some terms of the fibonacci sequence:
+```
+: over  >r dup r> swap ;
+: fib  recursive  r> drop  over + swap  dup .  dup 144 - ? fib ;
+: fib  1 0 fib ;
+
+fib
+1 1 2 3 5 8 13 21 34 55 89 144  ok
+```
+
+Compute the number of cans in a triangular stack of height n.
+For example a stack of height 3 contains 6 cans.
+```
+  x
+ x x 
+x x x
+```
+
+```
+variable cans
+: c  recursive  r> drop  dup cans @ + cans !  1 -  dup ?  c ;
+: c  c ;
+: can-stack  0 cans !  c  cans @ ;
+
+3 can-stack .
+6  ok
+10 can-stack .
+55  ok
+```