Fix truthy() for objects, make empty lists falsy

src/kiss/Prelude.hx

@@ -1,5 +1,7 @@
 package kiss;
 
+using Std;
+
 class Prelude {
     public static function add(a, b) {
         return a + b;
@@ -69,13 +71,17 @@ class Prelude {
             case TBool: (v : Bool);
             default:
                 // Empty strings are falsy
-                var str = cast(v, String);
+                if (v.isOfType(String)) {
-                if (str != null) {
+                    var str:String = cast v;
                     str.length > 0;
+                } else if (v.isOfType(Array)) {
+                    // Empty lists are falsy
+                    var lst:Array<Dynamic> = cast v;
+                    lst.length > 0;
                 } else {
                     // Any other value is true by default
                     true;
-                }
+                };
         }
     }
 

src/test/cases/BasicTestCase.hx

@@ -117,6 +117,8 @@ class BasicTestCase extends Test {
         Assert.equals(false, BasicTestCase.myIf6);
         Assert.equals(true, BasicTestCase.myIf7);
         Assert.equals(false, BasicTestCase.myIf8);
+        Assert.equals(false, BasicTestCase.myIf9);
+        Assert.equals(true, BasicTestCase.myIf10);
     }
 
     function testMacros() {

src/test/cases/BasicTestCase.kiss

@@ -62,6 +62,8 @@
 (defvar myIf6 (if false true false))
 (defvar myIf7 (if "string" true false))
 (defvar myIf8 (if "" true false))
+(defvar myIf9 (if [] true false))
+(defvar myIf10 (if [1] true false))
 
 (defvar :Int myInt 8)