Monad Transformers Step by Step Information Martin Grabmüller: Monad Transformers Step by Step, draft paper, October 2006. 12 pages, A4 format, English. Abstract In this tutorial, we describe how to use monad transformers in order to incrementally add functionality to Haskell programs. It is not a paper about implementing transformers, but about using them to write elegant, clean and powerful programs in Haskell. Download This article is available electronically: [ PDF ] The source code of this article, in the form of a Literate Haskell script, is also available: [ Transformers.lhs ] BibTeX Entry @Unpublished{Grabmueller2006MonadTransformers, author = {Martin Grabm{\"u}ller}, title = {{Monad Transformers Step by Step}}, note = {Draft paper}, month = {October}, year = 2006, abstract = {In this tutorial, we describe how to use monad transformers in order to incrementally add functionality to Haskell programs.
Haskell for all Haskell Lectures - CS 1501 Lecture 1 Outlines class structure, syllabus, grading policies, and reference text. Introduces the origin and theory behind Haskell. Lecture 2 Introduces Lists and Tuples, the most important data structures in Haskell. Lecture 3 Explores Haskell's strong Type system and Typeclasses. Lecture 4 Covers proper syntax in writing longer Haskell code. Lecture 5 Shows how to create your own data types to customize Haskell for you needs. Lecture 6 Investigates higher order functions such as maps, filters, folds, and a whole lot more.
sol/doctest-haskell You Could Have Invented Monads! (And Maybe You Already Have.) If you hadn't guessed, this is about monads as they appear in pure functional programming languages like Haskell. They are closely related to the monads of category theory, but are not exactly the same because Haskell doesn't enforce the identities satisfied by categorical monads. Writing introductions to monads seems to have developed into an industry. There's a gentle Introduction, a Haskell Programmer's introduction with the advice "Don't Panic", an introduction for the "Working Haskell Programmer" and countless others that introduce monads as everything from a type of functor to a type of space suit. But all of these introduce monads as something esoteric in need of explanation. But what I want to argue is that they aren't esoteric at all. Many of the problems that monads try to solve are related to the issue of side effects. Side Effects: Debugging Pure Functions In an imperative programming language such as C++, functions behave nothing like the functions of mathematics. Solution and
Haskell from C: Where are the for Loops? | FP Complete If you're coming from a language like C, Haskell can take some getting used to. It's typical for a new language to feel a little different, but in Haskell the differences are more dramatic, and more fundamental. In particular... Where are the for loops? In most imperative languages, for loops are all over the place, and are used for a wide variety of different things. In Haskell, control structures are more expressive. Consider the simple example of computing the norm of a vector. Conceptually, there are three stages to this computation: mapSq: Square each elementsum: Compute the sumsqrt: Compute the square root We can think of the first step as building (at least abstractly) a new array whose ith element is y[i] = x[i] * x[i]. Putting everything in terms of functions, we can write this (in Haskell-like pseudocode) as norm(x) = sqrt(sum(mapSq(x))) , To clean up the syntax a bit, we can instead use the notation for function composition and write norm(x) = (sqrt ○ sum ○ mapSq)(x) , or just where
Gentle introduction to Haskell This is the master HTML version of the Gentle Introduction To Haskell, version 98. Revised June, 2000 by Reuben Thomas. You may download the following: Brief Table of Contents. All code in this tutorial, with additional commentary, is found in the code directory packaged with this tutorial. Premission is granted to correct, improve, or enhance this document. Copyright (C) 1999 Paul Hudak, John Peterson and Joseph Fasel Permission is hereby granted, free of charge, to any person obtaining a copy of "A Gentle Introduction to Haskell" (the Text), to deal in the Text without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Text, and to permit persons to whom the Text is furnished to do so, subject to the following condition: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Text.
Haskell for all: Introductions to advanced Haskell topics Many people bemoan the sharp divide between experts and beginning Haskell programmers. One thing I've noticed is that "advanced" Haskell topics all have one thing in common: there exists only one good tutorial on that topic and only the experts have found it. This post is a collection of links to what I consider to be the definitive tutorials on these topics. Monads Monads are technically not an advanced Haskell topic, but I include this topic in the list because the vast majority of monad tutorials are terrible and/or misleading. Monad Transformers One thing that perpetually boggles me is that the blogosphere has almost no posts explaining how to use monad transformers. Parsing Outsiders comment that monads only exist to paper over Haskell's weaknesses until they discover monadic parsers. You also want to understand parser combinators for another reason: Haskell parser combinator libraries are light-years ahead of Haskell regular expression libraries. Free Monads Coroutines Lenses Conclusion
Some interesting features of Haskell’s type system « Wolfgang Jeltsch One of the most important ingredients of Haskell is its type system. Standard Haskell already provides a lot of useful mechanisms for having things checked at compile time, and the language extensions provided by the Glasgow Haskell Compiler (GHC) improve heavily on this. In this article, I will present several of Haskell’s type system features. Some of them belong to the standard, others are only available as extensions. This whole article was written as a literate Haskell file with ordinary text written in Markdown. Prerequisites We first enable some language extensions that we will use in this article: {-# LANGUAGE MultiParamTypeClasses, TypeFamilies #-} We will reimplement some bits of the Prelude for illustration purposes, and we will use functions from other modules whose names clash with those of certain Prelude functions. import Prelude hiding (Eq (..), Functor (..), lookup, (!!)) Furthermore, we need some additional modules for example code: Kinds newtype Identity val = Identity val
Raincat | 2D Puzzle Game 2D puzzle game featuring a fuzzy little cat "Watching the cat walk is so soothing." "He's so cute! Look at him go... go Raincat, go!" Download to play Raincat! Written in Haskell Get the Source! what fans have said "Raincat is amazing. how the cat sauntering in the rain came to be The project proved to be an excellent learning experience for the programmers. It's always raining in Pittsburgh, which makes for gray days while cats are just adorable—perfect for brightening up such days. Your goal is simple: guide the fuzzy cat safe and dry to the end of each level. Become our fan on Facebook! As students who make games for fun, we understand that our product isn't perfect. Finally, we'd like to mention that Project Raincat placed first in GCS Gold during the following spring semester release party. made by people who like cats maybe a little too much Team on the GCS Project Page for your kitty watching pleasure Thanks for visiting Project Raincat!
untitled The Haskell Phrasebook is a free quick-start Haskell guide comprised of a sequence of small annotated programs. It provides a cursory overview of selected Haskell features, jumping-off points for further reading, and recommendations to help get you writing programs as soon as possible. Source code To follow along and run the code examples, get the source files from github.com/typeclasses/haskell-phrasebook. We welcome requests and contributions, and we’re grateful to all who have submitted example code. The code may be modified and redistributed for any non-commercial purpose with attribution. Libraries Here is the complete list of libraries utilized by the example programs: Related work The style of the Phrasebook and many of its examples are inspired by Go by Example and Rust by Example.