The Monad Challenges
A set of challenges for jump starting your understanding of monads.
Outline
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Do Notation – Set 2
As with the previous set, you will want to create a Monad instance for your Maybe data type.
Once that is accomplished, rewrite the following functions using do syntax:
queryGreek :: GreekData -> String -> Maybe Double
addSalaries :: [(String, Integer)] -> String -> String -> Maybe Integer
tailProd :: Num a => [a] -> Maybe a
tailSum :: Num a => [a] -> Maybe a
tailMax :: Ord a => [a] -> Maybe aYou should import Set2 so that you can use the helper functions you wrote in that set.
You can test queryGreek with the following assertions:
queryGreek greekDataA "alpha" == Just 2.0
queryGreek greekDataA "beta" == Nothing
queryGreek greekDataA "gamma" == Just 3.3333333333333335
queryGreek greekDataA "delta" == Nothing
queryGreek greekDataA "zeta" == Nothing
queryGreek greekDataB "rho" == Nothing
queryGreek greekDataB "phi" == Just 0.24528301886792453
queryGreek greekDataB "chi" == Just 9.095238095238095
queryGreek greekDataB "psi" == Nothing
queryGreek greekDataB "omega" == Just 24.0