uniform half4 colorRed, colorGreen;

half4 main(float2 coords) {
    // The inner comparisons against colors should evaluate to true in every component.
    // The outer comparison should evaluate to `true == true`, so is true in each channel.
    bool4 result = equal(lessThan(colorRed, half4(2.0)),
                         greaterThan(half4(3.0), colorGreen));

    return all(result) ? colorGreen : colorRed;
}