Re: [Haskell-cafe] creating a type based on a string

What is stopping you from using an enumeration type? data Tag = A | B data X = X String Tag op "a" = X "a" A op "b" = X "b" B On 9/2/10 1:31 PM, Andrew U. Frank wrote:

I have a user input (string) and need to select one of two types. depending what the input is. is this possible?

data A data B

data X n = X String

op :: String -> X n op "a" = X "a" :: X A op "b" = X "b" :: X B

this does obviously not compile. is there a way to achieve that the type X A is produced when the input is "a" and X B when the input is "b"?

thank you for help! andrew

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