[Haskell-cafe] type class constraints headache

[muneson]

When writing a command-line interface I ran into type class conflicts
I don't understand. Could anyone explain why ghc 6.10.4 compiles this

> methods :: (Eq a) => [(String, a)]    
> methods = 
>   [ ("method1", undefined ) 
>   , ("method2", undefined)
>   ]
  

but not the following?

> methods :: (Eq a) => [(String, a)]    
> methods = 
>   [ ("method1", undefined ) 
>   , ("method2", undefined)
>   ]
>
> enumerateMethodNames :: [String]
> enumerateMethodNames = map fst methods 


thanks,

Marcus

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