Minor tweaks

examples/todomvc/src/main.rs

@@ -40,9 +40,6 @@ fn main() {
     let (sender2, receiver2) = signal::unsync::mutable(vec![width]);
     let (sender3, receiver3) = signal::unsync::mutable(vec![width]);
 
-
-    trace_macros!(true);
-
     /*let style_width = receiver1.switch(move |x| {
         receiver2.clone().switch(move |y| {
             receiver3.clone().map(move |z| {
@@ -54,12 +51,10 @@ fn main() {
     let style_width = map_rc! {
         let x: Rc<u32> = receiver1,
         let y: Rc<Vec<u32>> = receiver2,
-        let _z: Rc<Vec<u32>> = receiver3 =>
-        Some(format!("{}px", *x + y[0]))
+        let z: Rc<Vec<u32>> = receiver3 =>
+        Some(format!("{}px", *x + y[0] + z[0]))
     };
 
-    trace_macros!(false);
-
 
     html!("div", {
         style("border", "10px solid blue");

src/signal.rs

@@ -352,9 +352,11 @@ impl<A, B, C> Signal for FilterMap<A, B>
                         self.first = false;
                         return State::Changed(Some(value));
                     },
-                    None => if self.first {
-                        self.first = false;
-                        return State::Changed(None);
+                    None => {
+                        if self.first {
+                            self.first = false;
+                            return State::Changed(None);
+                        }
                     },
                 },
                 State::NotChanged => return State::NotChanged,