adding branching and conversions

example/shader.nzsl

@@ -1,17 +1,24 @@
-[nzsl_version("1.1")]
-module;
+ [nzsl_version("1.1")]
+ [feature(float64)]
+ module;
+ 
+ struct FragOut
+ {
+     [location(0)] color: vec4[f32]
+ }
 
-struct FragOut
-{
-    [location(0)] color: vec4[f32]
-}
+ [entry(frag)]
+ fn main() -> FragOut
+ {
+     let op1: f64 = 0.0;
+     let op2: f64 = 9.0;
+     let color: f32;
+     if (op1 == op2)
+         color = f32(op1);
+     else
+         color = f32(op2);
 
-[entry(frag)]
-fn main() -> FragOut
-{
-	let ratio = vec4[f32](2.0, 2.0, 8.0, 0.25);
-
-    let output: FragOut;
-    output.color = vec4[f32](4.0, 3.0, 2.0, 1.0) * ratio;
-    return output;
-}
+     let output: FragOut;
+     output.color = vec4[f32](color, color, color, color);
+     return output;
+ }