Ralette Grammar (WIP).red

ralette-grammar: [
   collect any [
      ['decompose [
         'rgb keep ([
            r: (color/1) / 255.0
            g: (color/2) / 255.0
            b: (color/3) / 255.0
         ]) |
         'hsl keep ([
            h: (color/1) / 255.0
            s: (color/2) / 255.0
            l: (color/3) / 255.0
         ]) |
         'hsv keep ([
            h: (color/1) / 255.0
            s: (color/2) / 255.0
            v: (color/3) / 255.0
         ])]
      ] |
      ['compose [
	    'rgb keep ([
               pack3 r g b
	    ]) |
	    'hsl keep ([
               pack3 h s l
	    ]) |
	    'hsv keep ([
               pack3 h s v
	    ])
	 ]
      ] |
      ['m 'from
	 'rgb keep ([
	    minc: min min r g b
	    maxc: max max r g b
	 ])
      ] |
      ['chroma 'from
	 'rgb keep ([
	    chroma: to float! (maxc - minc)
	 ])
      ] |
      ['hue 'from
	 'rgb keep ([
	     h: 0
	       if chroma <> 0 [
		  if maxc = r [h: modulo ((g - b) / chroma) 6]
		  if maxc = g [h: ((b - r) / chroma) + 2]
		  if maxc = b [h: ((r - g) / chroma) + 4]
	       ]
	    h: (h * 60.0)])
      ] |
      ['lightness 'from 'rgb keep ([
         l: (maxc + minc) * 0.5
	 ])
      ] |
      ['saturation 'from 'rgb 'for 'hsl keep ([
         s-hsl: either chroma <> 0 [
	    chroma / (1 - absolute (2 * lightness - 1))
         ][
	    0
         ]])
      ] |
      ['return [
	    ['hue keep ([h])] |
	    ['lightness keep ([l])] |
	    ['saturation 'for 'hsl keep ([s-hsl])]
         ]
      ]
   ]
]