[Haskell-cafe] creating a type based on a string
Andrew U. Frank
frank22 at geoinfo.tuwien.ac.at
Thu Sep 2 16:31:50 EDT 2010
I have a user input (string) and need to select one of two types.
depending what the input is. is this possible?
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!
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