[Haskell-cafe] deriving Data.HashTable - stack overflow

Lyle Kopnicky lists at qseep.net
Fri Aug 9 08:29:02 CEST 2013


I chose not to introduce another dependency. I just implemented the hash
function by delegating to the Show instance of the nested type:

data ValType = FloatType | IntType | StringType
    deriving (Show,Eq)

data VarName = VarName ValType String
    deriving (Show,Eq)

instance Hashable VarName where
    hash (VarName t n) = hash (show t ++ n)

Not super-efficient, but it'll be fine. The printString function (defined
in that other package) uses a single character prefix for each ValType.

- Lyle
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