動かして遊んで学ぶHaskell gloss・hamilton・コモナドを使ってできること
2018年11月10日、Haskell-jpが主催するイベント「Haskell Day 2018」が開催されました。純粋関数型プログラミング言語Haskellをテーマに、Haskellに興味のある人から入門者、ちょっとできる人まで、様々な層に向けたプレゼンテーションを行った本イベント。実務から研究まで、幅広いHaskellの事例を共有します。プレゼンテーション「gloss: 動かして遊んで学ぶHaskell」に登壇したのは、lotz氏。講演資料はこちら gloss: 動かして遊んで学ぶHaskell lotz氏：「gloss: 動かして遊んで学ぶHaskell」というタイトルで発表させていただきます。 まず自己紹介すると、lotzといいます。 僕もHaskellは趣味で、ふだんは半蔵門で働くエンジニアです。SNSのIDをスライドに載せているので、質問があればTwitterで、気軽に声かけて
コモナドを使った抽象化の威力をライフゲームで試してみた - Qiita
class Functor m => Monad m where return :: a -> m a (>>=) :: (a -> m b) -> m a -> m b join :: m (m a) -> m a join = (>>= id) k >>= m = join $ fmap k m extract は return と、extend は >>= と、duplicate は join と、それぞれなんとなく反対になってるような気がしますよね？（m と w も上下反対の対応がありますねｗ） コモナドの感覚を掴むために具体的な実装を見てみましょう。 -- | List Zipper data Z a = Z [a] a [a] left, right :: Z a -> Z a left (Z (l:ls) c rs) = Z ls l (c:rs) right (Z ls c
Who needs HashLife when you have comonads?
Improving a naive implementation of the Game of Life with an elegant and performant solution. Introduction I’m going to talk a little bit about Conway’s Game of Life, comonads in practical use, and the performance improvement that they have to offer. If you already know what the GoL is, skip the introduction, and if you’re already familiar with comonads and how they are defined in Haskell, feel fr
Comonadic Markov Chain Monte Carlo · jtobin.io
Some time ago I came across a way to in-principle perform inference on certain probabilistic programs using comonadic structures and operations. I decided to dig it up and try to use it to extend the simple probabilistic programming language I talked about a few days ago with a stateful, experimental inference backend. In this post we’ll Represent probabilistic programs as recursive types paramete
Functorial Blog - Comonads as Spaces
by Phil Freeman on 2016/08/07 I feel like I've had a good intuition for monads for some time, but I've struggled to really get a handle on comonads until recently. I'd like to present an application of comonads which I think provides a helpful intuition, and then interpret several comonads in that setting. Introduction In PureScript, we have several user interface libraries. They are all slightly
Functorial Blog - Comonads and Day Convolution
The Day convolution of two functors is another functor, defined as follows: data Day f g a where Day :: (x -> y -> a) -> f x -> g y -> Day f g a There is an implementation of Day in Edward Kmett's kan-extensions package on Hackage. Day Convolution of Comonads While writing my last post, I was looking for a way to combine comonads, and found out some interesting things about Day convolution in the
Comonads in Haskell
Comonads are the category-theoretic dual of monads. While monads have been found to be a very useful design pattern for structuring programs in functional languages, such as Haskell, comonads have so far failed to gain much traction. In this talk we will look at what comonads are and how they are defined in Haskell, comparing them with the Haskell definition of monads. We will then look at some sp
GitHub - plaidfinch/GQFC: Source material for "Functional Pearl: Getting a Quick Fix on Comonads"
This repository is the source for the paper: K. Foner. "Functional Pearl: Getting a Quick Fix on Comonads." In Proceedings of the 2015 ACM SIGPLAN Symposium on Haskell. ACM, 2015. A preview of what's inside... The quickest way to read the paper is to download the rendered pre-print (PDF). The paper is written in literate Haskell of the LaTeX flavor. It can be compiled both to a readable PDF and to
Part II: PNGs and Moore - School of Haskell | School of Haskell
Interactive code snippets not yet available for SoH 2.0, see our Status of of School of Haskell 2.0 blog post Last time I showed how we can render an automaton in your browser using existing tools. This time we're going to roll a few of our own, so we can render fancier things. The SVG we generated last time was just too slow for many users and some folks complained that they couldn't see it at al
コモナドによる対話 - Qiita
外界との対話をモナドではなくコモナドで表現することについての不確かで曖昧なアイデア話です．書き散らかしのメモですが，アドバイス，ツッコミをいただければ幸いです． 外界との対話（インタラクション） 外界との対話は， 実行時 にならないと 確定 しない計算対象を扱わなければなりません．ということは，対話を含むプログラムは 動的 で，ある種の 非決定性 があると考えられます． 純粋な関数 関数プログラミングではプログラムは，ある型の値から別の型の値への関数です．
jaspervdj - Image Processing with Comonads
A simple real-world example showing an image-processing Comonad Published on November 27, 2014 under the tag haskell Introduction A Comonad is a structure from category theory dual to Monad. Comonads are well-suited for image processing – Pretty much everyone on the internet Whenever Comonads come up, people usually mention the canonical example of evaluating cellular automata. Because many image
GitHub - plaidfinch/ComonadSheet: A library for expressing "spreadsheet-like" computations with absolute and relative references, using fixed-points of n-dimensional comonads.
A library for expressing "spreadsheet-like" computations with absolute and relative references, using fixed-points of n-dimensional comonads. A sheet is an n-dimensionally nested Tape, which is a stream infinite in both left and right directions, with a focus element. For instance, type Sheet1 a = Nested (Flat Tape) a, which is isomorphic to Tape a. Nested Tapes describe multi-dimensional grid-lik
Comonads in Haskell
Comonads are the category-theoretic dual of monads. While monads have been found to be a very useful design pattern for structuring programs in functional languages, such as Haskell, comonads have so far failed to gain much traction. In this talk we will look at what comonads are and how they are defined in Haskell, comparing them with the Haskell definition of monads. We will then look at some sp
Part II: PNGs and Moore - School of Haskell | School of Haskell
Interactive code snippets not yet available for SoH 2.0, see our Status of of School of Haskell 2.0 blog post Last time I showed how we can render an automaton in your browser using existing tools. This time we're going to roll a few of our own, so we can render fancier things. The SVG we generated last time was just too slow for many users and some folks complained that they couldn't see it at al
Comonads ←
Comonads monads 23 While monads are a very useful abstraction for handling side effects, there’s a class of effects they can’t address. For those, you need a related abstraction called comonads. IO All programs must have side effects to be useful. There must exist a way for information to get into and out of a program. There are two ways for a program to aquire information to work on. Synchronous
Comonads are neighbourhoods, not objects
Code and ideas in computer science. And maybe a short story or two. Gabriel Gonzalez, the author of the well-known pipes package, has written a blog post in which he claims that comonads are objects. I think he is mistaken, but I can't blame him; I used to be quite confused about comonads myself. Comonads are not objectsTo motivate the purported equivalence between objects and comonads, Gabriel gi
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Reddit - Dive into anything
Kenneth Foner - Getting a Quick Fix on Comonads
Cellular Automata Using Comonads
Comonads, Life and Klein Bottles