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Learn You a Haskell explains the unwords function. $unwords ["hey","there","mate"] "hey there mate" Here's my implementation. …

Please review my implementation for correctness and idiomatic Haskell. …

Given the following definitions of Functor and Coproduct from fp-course: class Functor f where (<$>) :: (a -> b) -> f a -> f b class Functor f => Applicative f where pure :: a - …

The following function finds all local maxima. A local maxima is an element of a list such that it's greater than either of its neighbor elements. An element with 1 neighbor is not a local maximum. …

Learn You a Haskell mentions the partition function: partition takes a list and a predicate and returns a pair of lists. …

I've implemented the following nub' or "give distinct elements of list" function: nub' :: (Eq a) => [a] -> [a] nub' [] = [] nub' xs = nubHelper xs [] nubHelper :: (Eq a) => [a] -> [a] -> [a] nubHelp …

Given the Free Monad, and my Eq, Show, and Functor instances, I attempted to verify the first Functor law using QuickCheck: data Free f a = Var a | Node (f (Free f a)) I defined the …

I'm implementing transpose in Haskell. -- transpose [[1,2,3],[4,5,6],[7,8,9]] -- [[1,4,7],[2,5,8],[3,6,9]] Please give it a look. … [] head' (x:xs) = [x] tail' :: [a] -> [a] tail' [] = [] tail' (x:xs) = xs flatten' :: [[a]] -> [a] flatten' as = foldl (\acc x -> acc ++ x) [] as Side note - I know that I could look at the Haskell …

In the same vein as the (+++) function on JoinList and indexJ on JoinList, I implemented dropJ to drop elements from a JoinList. Here's my attempt: dropJ ::(Sized b, Monoid b) => Int -> JoinList b a …

conduit offers the following exercise: Write a conduit that consumes a stream of Ints. It takes the first Int from the stream, and then multiplies all subsequent Ints by that number and sends them …

Originally I posted this incorrect attempt - Searching a Join List for an index. Given a JoinList: data JoinList m a = Empty | Single m a | Append m (JoinList m a …

This function checks if a list is sorted. isSorted' :: (Ord a) => [a] -> [a] -> a -> Bool isSorted' [] [] _ = True isSorted' (x:xs) [] _ = isSorted' xs xs (head xs) isSorted' orig (x:xs) a | a > x …

Looking at this Typeclassopedia exercise, I typed out foldTree on the following type: data ITree a = Leaf (Int -> a) | Node [ITree a] And my implementation of Functor: instance Functor (ITree) whe …

Per this homework, I'm trying to implement a Fractional (Stream Integer) where the stream represents coefficients of polynomials: where Q is defined as Q = (A'/b0) + x((1/b0)(A' − QB0)). wher …

I attempted (incorrectly) to implement foldTree here. Recently, I updated it per Petr's help: treeFold :: (b -> [b] -> b) -> (a -> b) -> Tree a -> b treeFold f g tree = f (g (rootLabel tree)) (map ( …