[Haskell] Overloading show
s.zaubzer at gmx.at
Fri Sep 10 18:37:29 EDT 2004
I am relatively new to Haskell (actually it's my second day) and I have
the following problem:
If I define a new datatype, for example a Binary tree, how can i use the
show function to put an instance of my datatype into a String
representation. I have seen in different Tutorials that there is a way
for overloading the show function for my own type, and I tried out, what
was presented in the tutorials, but it didn't work. Does somebody know,
how to manage this?
Here my attempts:
data Entry a = EmptyEntry | MakeEntry a a
showEntry :: (Show a) => Entry a -> String
showEntry EmptyEntry = "Empty"
showEntry MakeEntry a b = show a ++ ": " ++ show b
what am I doing wrong? I have seen this way on some tutorials.
btw: I am working with Hugs98
thank you in advance for your help
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