Because for more advanced cases requires flatMap instead of just map and filter. You can only nested as a callback hell instead of streamlined syntactic sugar.

Because for more advanced cases requires flatMap instead of just map and filter. You can only nested as a callback hell instead of streamlined syntactic sugar. Take an example in 'Learn You a Haskell': [ (a,b,c) | c <- [1..10], b <- [1..c], a <- [1..b], a^2 + b^2 == c^2] b depends on c while a depends on b. You do need a Monadic operation instead of Functor/Applicative to do it because of the dependency in the contexts. And then you can think of solving the eight queen problem[0]. It's far more readable if you have a syntactic sugar, I just found a Scala example: [1]. [0] https://en.wikipedia.org/wiki/Eight_queens_puzzle https://en.wikipedia.org/wiki/Eight_queens_puzzle [1] https://stackoverflow.com/questions/42789854/n-queens-in-scala https://stackoverflow.com/questions/42789854/n-queens-in-sca...