Category "haskell"

How do I run the tests that are part of an installed/installing Cabal package?

I have a Haskell package I've installed from Hackage, using cabal and would like to run the tests suites that are part of the package, but it isn't clear to me

Computational Complexity of Higher Order Functions?

Map and filter seem like they would be linear O(n) because they only have to traverse a list once, but is their complexity affected by the function being passed

Is there a cleaner way of converting an Either to an ExceptT?

I have some functions which return Either values and I'd like to use them in an IO do block with what I think is called "short circuit" behaviour so that any Le

Getting 'a' value from 'Maybe a' return type in Haskell

I have a Haskell function eval :: WExp -> Memory -> WValue with a bunch of different instances of itself for different cases. For now, knowledge about WEx

Haskell: Continue program execution

I am very new to Haskell. My question might be very basic for you. Here I go- I am writing a program to create a series of numbers using a specific mathematica

Writing Algebraic Data Type in Scala

In Haskell, I can define a Tree: data Tree a = Empty | Node a (Tree a) (Tree a) How could I write this in Scala? I'm not sure how to keep the type paramete

How does an instance of "Arbitrary" looks for a tree?

In our CS-Lectures we currently learn about QuickCheck in Haskell. Now I got a task to use QuickCheck with the following tree-type: data Tree = Leaf Int | Node

What exactly does "effectful" mean

Time and again I read the term effectful, but I am still unable to give a clear definition of what it means. I assume the correct context is effectful computati

Haskell Monoid Instance Question for a newtype

I am trying to define an instance: newtype Join a = Join { getJoin :: a -> Bool } deriving Generic instance Monoid (Join a) where f <> g = ???

Understanding the Reader monad

I'm reading PureScript by Example and got to the part introducing the Reader monad. The example goes like this: createUser :: Reader Permissions (Maybe User) c

New state of the art in unlimited generation of Hamming sequence

(this is exciting!) I know, the subject matter is well known. The state of the art (in Haskell as well as other languages) for efficient generation of unbounded

Is implementing the words function possible without a postprocessing step after folding?

Real World Haskell, chapter 4, page 98 of the print asks if words can be implemented using folds, and this is my question too: Is it possible? If not, why? If i

Haskell ncurses

main :: IO() main = runCurses $ do setEcho False w <- defaultWindow canvas <- newWindow 19 19 0 0 panel <- newPanel canvas updateWindow canv

Reverse a list in haskell

I am trying to reverse a list. Following is my code: reverseList :: [Int] -> [Int] reverseList [] = [] reverseList (x:xs) = x:reverseList xs What ends u

Lazy Catalan Numbers in Haskell

How might I go about efficiently generating an infinite list of Catalan numbers? What I have now works reasonably quickly, but it seems to me that there should

Neural Network Always Produces Same/Similar Outputs for Any Input [closed]

I have a problem where I am trying to create a neural network for Tic-Tac-Toe. However, for some reason, training the neural network causes it

Implementing a language interpreter in Haskell

I want to implement an imperative language interpreter in Haskell (for educational purposes). But it's difficult for me to create right architecture for my inte