[Haskell-beginners] Type signature question
louis.guillaume.gagnon at gmail.com
Tue Jul 23 16:33:35 CEST 2013
I'm working on the second set of exercises in ch.03 of Real World Haskell
I wrote a palindromize function (:: [a] -> [a]) which transforms a
list in a palindrome (eg. [1,2,3] -> [1,2,3,3,2,1]) .
I wrote a isPalindrome function which checks whether a given list is
such a palindrome.
| odd (length xs) = False
| firstHalf == secondHalf =True
| otherwise = False
where half = div (length xs) 2
firstHalf = take half xs
secondHalf = reverse (drop half xs)
I would expect the type signature to be:
isPalindrome :: [a] -> Bool
but ghci gives me
is Eq a => [a] -> Bool
and I don't undestand why the "Eq a =>" shows up.
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