def hsla(hue, saturation, lightness, alpha)
if calc?(hue) || calc?(saturation) || calc?(lightness) || calc?(alpha)
return unquoted_string("hsla(#{hue}, #{saturation}, #{lightness}, #{alpha})")
end
assert_type hue, :Number, :hue
assert_type saturation, :Number, :saturation
assert_type lightness, :Number, :lightness
assert_type alpha, :Number, :alpha
check_alpha_unit alpha, 'hsla'
h = hue.value
s = saturation.value
l = lightness.value
Sass::Script::Value::Color.new(
:hue => h, :saturation => s, :lightness => l, :alpha => alpha.value)
end