type checking

1 files changed, 10 insertions, 6 deletions

diff --git a/ack.kpl b/ack.kpl
index 1eb7694..f27af3e 100644
--- a/ack.kpl
+++ b/ack.kpl
@@ -2,19 +2,23 @@
 // Ackermann function
 
 `export ack : Fn[m; n] $ (
-    ? !=(`type m; `type n) {
-        `panic "m and n must be the same type"
+    t : `type m;
+    ? |(t != `type n; t != Int[Any; Any; Any]) {
+        `panic "m and n must be the same type of Int"
+    }
+    ? t = Int[Any; .signed; Any] {
+        ? |(m < 0; n < 0) { `return 0 }
     }
     ? {
         m = 0 { n + 1 }
-        &(m > 0; n = 0) { ack `call_sync (m - 1; 1) }
-        &(m > 0; n > 0) { ack `call_sync (m - 1; ack `call_sync (m; n - 1)) }
+        &(m > 0; n = 0) { ack `sync (m - 1; 1) }
+        &(m > 0; n > 0) { ack `sync (m - 1; ack `sync (m; n - 1)) }
         { 0 }
     }
 )
 
 `export ack_string : Fn[m; n] $ (
-    String $ ("ack("; m; " "; n; ") = "; ack `call_sync (m; n); "\n")
+    String $ ("ack("; m; " "; n; ") = "; ack `sync (m; n); "\n")
 )
 
 `is_main Fn $ (
@@ -25,5 +29,5 @@
             "Usage: "; args `get 0; " "; args `get 1; " <m> <n>\n"
          )
     }
-    `print ack_string `call_sync (I64 $ args `get -2; I64 $ args `get -1)
+    `print ack_string `sync (I64 $ args `get -2; I64 $ args `get -1)
 )