@@ -31,9 +31,9 @@
 		foreach(i, Ti; T)
 		{
 			typed_args[i] = cast(Ti) args[i];
 			if( typed_args[i] is null )
-				throw genex!RuntimeException(pos, sprintf!"type mismatch on the argument %d"(i));
+				throw genex!RuntimeException(pos, sprintf!"type mismatch on the argument %d"(i+1));
 		}
 		try {
 			return dg(typed_args);
 		} catch( RuntimeException e ) {
@@ -50,14 +50,16 @@
 	ctx.set("-", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(lhs.data - rhs.data);} ));
 	ctx.set("*", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(lhs.data * rhs.data);} ));
 	ctx.set("/", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(lhs.data / rhs.data);} ));
 	ctx.set("%", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(lhs.data % rhs.data);} ));
-	ctx.set("<", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data < rhs.data ? 1: 0));} ));
-	ctx.set(">", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data > rhs.data ? 1: 0));} ));
-	ctx.set("<=", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data <= rhs.data ? 1: 0));} ));
-	ctx.set(">=", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data >= rhs.data ? 1: 0));} ));
-	ctx.set("==", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data == rhs.data ? 1: 0));} ));
-	ctx.set("!=", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt(lhs.data != rhs.data ? 1: 0));} ));
+	ctx.set("||", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt((lhs.data!=0) || (rhs.data!=0) ? 1:0));} ));
+	ctx.set("&&", "@v", native( (IntValue lhs, IntValue rhs){return new IntValue(BigInt((lhs.data!=0) && (rhs.data!=0) ? 1:0));} ));
+	ctx.set("<", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs < rhs ? 1: 0));} ));
+	ctx.set(">", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs > rhs ? 1: 0));} ));
+	ctx.set("<=", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs <= rhs ? 1: 0));} ));
+	ctx.set(">=", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs >= rhs ? 1: 0));} ));
+	ctx.set("==", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs == rhs ? 1: 0));} ));
+	ctx.set("!=", "@v", native( (Value lhs, Value rhs){return new IntValue(BigInt(lhs != rhs ? 1: 0));} ));
 	ctx.set("print", "@v", new FunValue(delegate Value(immutable LexPosition pos, Layer lay, Value[] args){
 		foreach(a; args)
 			write(a);
 		writeln("");
@@ -124,11 +126,13 @@
 				return (cast(FunValue)ctx.get(lay, "(system)", e.pos)).call(e.pos, "@v", [v]);
 		},
 		(VarExpression e)
 		{
+			if( lay == "@v" )
+				return ctx.get(e.var, lay, e.pos);
 			try {
 				return ctx.get(e.var, lay, e.pos);
-			} catch( RuntimeException ) {
+			} catch( Throwable ) { // [TODO] more precise...
 				// rise from @v
 				return (cast(FunValue)ctx.get(lay, "(system)", e.pos)).call(e.pos, "@v", 
 					[ctx.get(e.var, "@v", e.pos)]
 				);
@@ -204,9 +208,9 @@
 {
 	assert_eq( evalString(`@a x=1; @b x=2; @a(x)`).val, new IntValue(BigInt(1)) );
 	assert_eq( evalString(`@a x=1; @b x=2; @b(x)`).val, new IntValue(BigInt(2)) );
 	assert_eq( evalString(`let x=1; let _ = (@a x=2;2); x`).val, new IntValue(BigInt(1)) );
-	assert_throw!Error( evalString(`let x=1; let _ = (@a x=2;2); @a(x)`) );
+	assert_throw!Throwable( evalString(`let x=1; let _ = (@a x=2;2); @a(x)`) );
 }
 
 unittest
 {