Add Fibonacci in Forth

Author: ricardomaps

archive/f/forth/fibonacci.fth

@@ -0,0 +1,17 @@
+: fibonacci ( n --  )
+   0 1 rot 0 ?do       \ prepare the stack and loop
+      tuck +           \ calculate the next fibonacci number
+      i 1+ 0 .r ." : " \ print the current index
+      over 0 .r cr     \ print the current fibonacci number
+   loop
+   2drop ;
+
+: usage ( -- ) ." Usage: please input the count of fibonacci numbers to output" cr ;
+
+: main
+   argc @ 2 < if usage exit then
+   1 arg s>number? 0= if usage exit else drop then
+   fibonacci ;
+
+main
+bye