Haskell — Vel Tech Exam 2018

1.  Write a function df :: Int -> Int that returns the double factorial
    of a natural number. The double factorial of n is denoted n!! and is
    n(n − 2)(n − 4)….

2.  Write a function sumd :: Int -> Int that returns the sum of the
    digits of a natural number.

3.  Write a function dup :: [Int] -> [Int] that duplicates each element
    in a list.

4.  Write a function pal :: String -> Bool that tells if a string is a
    palindrome, ie, if it is equal to its reverse.

5.  Write a function apply2 :: (a -> a) -> a -> a that applies a
    function twice to some parameter.

Problem information

Author: Jordi Petit

Generation: 2026-02-03T17:01:44.383Z

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