99 questions/Solutions/2

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Revision as of 00:12, 11 May 2014 by EduardNicodei (talk | contribs) (Add foldl based solution.)
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(*) Find the last but one element of a list. 

myButLast :: [a] -> a
myButLast = last . init

myButLast' x = reverse x !! 1

myButLast'' [x,_]  = x
myButLast'' (_:xs) = myButLast'' xs

myButLast''' (x:(_:[])) = x
myButLast''' (_:xs) = myButLast''' xs

myButLast'''' = head . tail . reverse

myButLast''''' = snd.(foldl (\(a,b) c -> (c,a)) (e1, e2))
    where e1 = error "List too small!"
          e2 = error "List is null!"
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