[Haskell-cafe] Creating an instance of the Show Typeclass for a datatype
murilo.winter at gmail.com
Thu Dec 3 22:16:07 UTC 2015
As part of my exercise, I have to create an instance of the show typeclass
for a given data type defined as:
1. *type *stat *= (*String*, Int)*
*If* it was a data type, like:
1. data TrafficLight = Red | Yellow | Green
It would be as simple as doing:
1. instance Show TrafficLight where
2. show Red = "Red light"
3. show Yellow = "Yellow light"
4. show Green = "Green light"
However, I do not know how to declare the instance for a type, and then how
to access its elements (String and Int).
This is what I have so far, which does not work:
1. instance Show Stat where
2. show stat(a,b) = a
instance Show Stat where
show stat(a b) = b
(imagine, for example, I desire to write" the value of "String" is "Int").
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