past exam papers

Question 1

What is a higher-order function? Give an example in Haskell to explain why
higher-order functions are useful in functional programming.

Answer 1

A higher-order function is a function that takes other functions as arguments or returns a function as result.
any recurrence example.

Question 2

What is lazy evaluation? Give an example in Haskell to explain your answer

Answer 2

only evaluating as much as you need. e.g true or false if written well

Question 3

Give an example of a polymorphic function to explain the notion of parametric polymorphism.

Answer 3

no class constraints.
anything that uses [a] (like reverse etc)

Question 4

write a recursive ‘sorted’ algorithm without using adjPairs

Answer 4

sorted :: Ord a => [a] -> Bool
sorted[] = []
sorted (x : []) = []
sorted(x : y : xs) = x

Question 5

write a algorithm adjPairs that takes a list and divides it into a list of adjacent pairs

Answer 5

adjPairs :: [a] -> [(a, a)]
adjPairs[] = []
adjPairs(x : []) = []
adjPairs(x : y : xs) = (x, y) : adjPairs[y ++ xs]

Question 6

write an algorithm sorted using adjPairs

Answer 6

sorted[] = True
sorted xs = if any (== False) | then False
                    else true
                   where
                         [x < y | (x, y)