new files

Task/Ackermann-function/Sather/ackermann-function-1.sa

@@ -0,0 +1,19 @@
+class MAIN is
+
+  ackermann(m, n:INT):INT
+    pre m >= 0 and n >= 0
+  is
+    if m = 0 then return n + 1; end;
+    if n = 0 then return ackermann(m-1, 1); end;
+    return ackermann(m-1, ackermann(m, n-1));
+  end;
+
+  main is
+    n, m :INT;
+    loop n := 0.upto!(6);
+      loop m := 0.upto!(3);
+        #OUT + "A(" + m + ", " + n + ") = " + ackermann(m, n) + "\n";
+      end;
+    end;
+  end;
+end;

Task/Ackermann-function/Sather/ackermann-function-2.sa

@@ -0,0 +1,19 @@
+class MAIN is
+
+  ackermann(m, n:INTI):INTI is
+    zero ::= 0.inti; -- to avoid type conversion each time
+    one  ::= 1.inti;
+    if m = zero then return n + one; end;
+    if n = zero then return ackermann(m-one, one); end;
+    return ackermann(m-one, ackermann(m, n-one));
+  end;
+
+  main is
+    n, m :INT;
+    loop n := 0.upto!(6);
+      loop m := 0.upto!(3);
+        #OUT + "A(" + m + ", " + n + ") = " + ackermann(m.inti, n.inti) + "\n";
+      end;
+    end;
+  end;
+end;