Just another update

Task/Fibonacci-sequence/Fexl/fibonacci-sequence.fexl

@@ -1,26 +1,14 @@
-# fibonacci is the infinite list of all Fibonacci numbers.
-#
-# Note that this program uses the symbols "1" and "+".  You can specify
-# the definitions of those symbols however you like, allowing you to use
-# any system of arithmetic you need.  For example, you can use either the
-# built-in long arithmetic, or infinite precision arithmetic, by simply
-# defining "1" and "+" appropriately.
-
-\fibonacci =
+# (fib n) = the nth Fibonacci number
+\fib=
     (
-    \fibonacci == (\x\y
-        item x;
-        \z = (+ x y)
-        fibonacci y z
-        )
-
-    fibonacci 1 1
+    (@\loop\x\y\n
+    le n 0 x;
+    \z=(+ x y)
+    \n=(- n 1)
+    loop y z n
+    )
+    0 1
     )
 
-# OK, so that's the list of *all* Fibonacci numbers.  If you want the nth number,
-# you can extract it with the fib function as follows.  By the way, this *does*
-# have the effect of caching, so once a particular point in the sequence is
-# calculated, it doesn't have to be calculated again.
-
-# (fib n) is the nth fibonacci number, starting with n==0, or 1 if n is negative.
-\fib = (\n list_at fibonacci n 1)
+# Now test it:
+for 0 20 (\n say (fib n))