Quiz

What is the type of swap . swap?

1. (a, b) -> (a, b)
2. (a, b) -> (b, a)
3. a -> a

What is the type of \f g x -> (f x, g x)?

1. (a -> b) -> (c -> d) -> (a,c) -> (b, d)
2. (a -> b) -> (a -> c) -> a -> (b, c)
3. (a -> b) -> (b -> a) -> a -> (b, a)

What is the type of \t -> (fst . fst $ t, (snd . fst $ t, snd t))?

1. (a, (b, c)) -> (a, (b, c))
2. (a, (b, c)) -> ((a, b), c)
3. ((a, b), c) -> (a, (b, c))

What does the function foldr (\x xs -> xs ++ [x]) [] do?

1. It doesn’t change its input list at all
2. It changes the associativity of a list from left to right
3. It reverses its input list

What does the function foldr (\(x, y) zs -> x : y : zs) [] do?

1. It turns a list of pairs into a pair of lists
2. It turns a pair of lists into a list of pairs
3. It turns a list of pairs into a list of elements

What is the type of foldr (\n b -> n == 3 && b)?

1. (Foldable t, Eq a, Num a) => Bool -> t a -> Bool
2. (Foldable t, Eq a, Num a, Bool b) => b -> t a -> b
3. (Foldable t, Eq a, Num a) => Bool -> [ a ] -> Bool

What is the type of \x -> case x of (True, "Foo") -> show True ++ "Foo"?

1. Either Bool String -> String
2. (Bool, String) -> String
3. Show a => (Bool, String) -> a

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