Getting a list of all possible data type values in Haskell

Question

If I have a data type say:

data Color = Red | Yellow | Green

Is there a way I can turn this into a list of type [Color] getting all possibl

Answer 1

Surely delnan's answer is better. Since I do not know how to include a piece of code in a comment, I'll give a generalisation as a separate answer here.

allValues :: (Bounded a, Enum a) => [a]
allValues = [minBound..]

Now, this works for any type with a Bounded and Enum instance! And allColors is just a special case:

allColors :: [Color]
allColors = allValues

In many cases, you won't even need to define allColors separately.