Else statements and early returns

January 3, 2020

The early return statement is useful. Indicating that there is no more processing increases readability significantly.

I think that the most readable approach is to have early return statements and else statements. The else statement highlights to the reader the alternative flow paths. The early return statements highlights to the reader the flow end.

This dual approach's greater readability outweighs the minor increase in duplication.

Foldl

December 31, 2019

product_td :: Num a => [a] -> a product_td = _product 1 where _product v [] = v _product v (x:xs) = _product (v * x) xs Note: The base case _product v [] = v returns v, which is the result of the recursed function calls. or product_td :: Num a => [a] -> a product_td = foldl (*) 1 ...

Use foldr to define filter and map

January 12, 2020

Filter Without foldr _filter :: (a -> Bool) -> [a] -> [a] _filter p (x:xs) | p x == True = x : _filter xs | otherwise = _filter xs With folder _filter :: (a -> Bool) -> [a] -> [a] _filter p = foldr (\x xs -> if p x then x : xs else xs) [] Map Without foldr _map :: (a -> b) -> [a] -> [a] _map f [] = [] _map f (x:xs) = f x : _map f xs With foldr _map :: (a -> b) -> [a] -> [a] _map f = foldr (\x xs -> f x : xs) [] ...