add is_main to fib example

1 files changed, 14 insertions, 1 deletions

diff --git a/fib.kpl b/fib.kpl
index e8ebeb8..4b7fb15 100644
--- a/fib.kpl
+++ b/fib.kpl
@@ -1,10 +1,23 @@
 
 // Fibonacci sequence for all numeric types
 
-fib : Fn[n] $ (
+`export fib : Fn[n] $ (
     ? {
         n <= 0 { 0 }
         n < 3 { 2 }
         { `call_sync(fib; n - 1) + fib `call_sync n - 2 }
     }
 )
+
+`is_main Fn $ (
+    ( args ) : `use "sys"
+    ? 3 != `length args {
+        `return `error String $ (
+            "Got: "; " " `join args; "\n"
+            "Usage: "; args `get 0; " "; args `get 1; " <number>\n"
+         )
+    }
+    n : I64 $ args `get -1
+    ( print ) : `use "io"
+    print `call_sync String $ ("fib("; n; ") = "; fib `call_sync n; "\n")
+)