colour<-convert

colour <-convert: name -> colour

Type-checker hook. First looks the name up in @colours (already-constructed colours). Otherwise:

If the name starts with # and has 3, 4, 6 or 8 hex digits after it, interpret it as a CSS hex literal:
#c0453f -> R=192, G=69, B=63, A=255

With three or four hex digits, each digit is doubled (#abc â¡ #aabbcc). With four or eight digits the trailing byte is the alpha channel.
Otherwise the name is passed to the OS colour database for resolution.