[Haskell-cafe] Printing list of enum type
Eugene Kirpichov
ekirpichov at gmail.com
Tue Apr 14 09:18:34 EDT 2009
1. data Color = Red | Green | Blue deriving (Show)
2. [Red,Black,White]
2009/4/14 michael rice <nowgate at yahoo.com>:
> What do I need to add to this Color enum type to print a list of them?
>
> Michael
>
> ===============
>
> data Color
> = Red
> | Blue
> | Green
> | Yellow
> | Orange
> | Brown
> | White
> | Black
>
> instance Show Color where
> show Red = "Red"
> show Blue = "Blue"
> show Green = "Green"
> show Yellow = "Yellow"
> show Orange = "Orange"
> show Brown = "Brown"
> show White = "White"
> show Black = "Black"
>
> ======================
>
> Ok, modules loaded: Main.
> *Main> Red
> Red
> *Main> Black
> Black
> *Main> [Red Black White]
>
> <interactive>:1:1:
> Couldn't match expected type `Color -> Color -> t'
> against inferred type `Color'
> In the expression: Red Black White
> In the expression: [Red Black White]
> In the definition of `it': it = [Red Black White]
>
>
>
>
>
>
>
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>
--
Eugene Kirpichov
Web IR developer, market.yandex.ru
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