Conduit最速入門2019 - Qiita
メリークリスマス。 アドベントカレンダーの枠が埋まっていないので、ちょっとお邪魔してconduitをやります。 conduitはバージョン1.3系統で大きくAPIが変わっているのですが、日本語による新しい解説が見当たらないので、簡単にチュートリアルをやっていこうと思います。 Conduitは「読み込む→何かする→書き込む→繰り返し」みたいな処理をHaskellで書くためのライブラリ、またはフレームワークです。 本来、純粋なシーケンス相手であれば、こういう処理は得意なはずのHaskellなのですが、読み書きが入って来ると途端に話が複雑になります。 実質的な選択肢は3つ。 普通にdo文で手続き型っぽく書く Lazy IO なんかフレームワークを使う 1は実は最善策という説がありますが、やめておきましょう。2はトイプログラムには良いのですが、実用的にはいろいろ問題がある事が分かっています。 とい
Sharing, Space Leaks, and Conduit and friends
TL;DR: Sharing conduit values leads to space leaks. Make sure that conduits are completely reconstructed on every call to runConduit; this implies we have to be careful not to create any (potentially large) conduit CAFs (skip to the final section “Avoiding space leaks” for some details on how to do this). Similar considerations apply to other streaming libraries and indeed any Haskell code that us
First class stream fusion
Yesod is a Haskell web framework for productive development of type-safe, RESTful, high performance web applications. February 28, 2016By Michael SnoymanView source on Github This is a blog post about a little thought experiment I've been playing with recently. The idea has been bouncing around in my head for a few years now, but some recent discussions with coworkers at FP Complete (particularly
plumbum - Rust
Plumbum (latin for lead) is a port of Michael Snoyman's excellent conduit library. It allows for production, transformation, and consumption of streams of data in constant memory. It can be used for processing files, dealing with network interfaces, or parsing structured data in an event-driven manner. Features Large and possibly infinite streams can be processed in constant memory. Chunks of data
Parallel/Pipelined Conduit
Summary: I wrote a Conduit combinator which makes the upstream and downstream run in parallel. It makes Hoogle database generation faster. The Hoogle database generation parses lines one-by-one using haskell-src-exts, and then encodes each line and writes it to a file. Using Conduit, that ends up being roughly: parse =$= write Conduit ensures that parsing and writing are interleaved, so each line
Counties and Conduit - Levi Schuck
About two years ago, I worked with my grandpa to produce a database of cities (at the latitude and longitude level) and historic counties / state based on GIS files with polygons from Newberry. It wasn’t too difficult, I loaded them into PostGIS on a local PostgreSQL instance, joined based on cities being inside a polygon or not, where each polygon had an associated historic county name, state, te
Thoughts on Conduits
Summary: I'm growing increasingly fond of the Conduit library. Here I give my intuitions and some hints I'd have found useful. Recently I've been working on converting the Hoogle database generation to use the Conduit abstraction, in an effort to reduce the memory and improve the speed. It worked - database generation has gone from 2Gb of RAM to 320Mb, and time has dropped from several minutes (or
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The Haskell programming language community. Daily news and info about all things Haskell related: practical stuff, theory, types, libraries, jobs, patches, releases, events and conferences and more...
shell-conduit: Write shell scripts in Haskell with Conduit
shell-conduit: Write shell scripts in Haskell with Conduit As part of my series of write-about-personal-projects, my latest obsession is writing shell scripts with Michael Snoyman’s Conduit. Here is my package, shell-conduit. It’s still in the experimental phase, but I don’t forsee any changes now for a while. Bash is evil I hate writing scripts in Bash. Until now, it was the easiest way to just w
IAP: conduit stream fusion - FP Complete
Both the changes described in this blog post, and in the previous blog post, are now merged to the master branch of conduit, and have been released to Hackage as conduit 1.2.0. That doesn’t indicate stream fusion is complete (far from it!). Rather, the optimizations we have so far are valuable enough that I want them to be available immediately, and future stream fusion work is highly unlikely to
IAP: Speeding up conduit - FP Complete
As most of us know, performance isn’t a one-dimensional spectrum. There are in fact multiple different ways to judge performance of a program. A commonly recognized tradeoff is that between CPU and memory usage. Often times, a program can be sped up by caching more data, for example. conduit is a streaming data library. In that sense, it has two very specific performance criterion it aims for: Con
RFC: New Data.Conduit.Process
Yesod is a Haskell web framework for productive development of type-safe, RESTful, high performance web applications. July 10, 2014By Michael SnoymanView source on Github I've been working on a new iteration of the Data.Conduit.Process API over the past few days. The current API (provided by the process-conduit package), has some issues. So I'm starting over with a new API, and will be including t
Building an Async Chat Server with Conduit - 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 IntroductionAs a more advanced and practical exercise for learning how to use the data streaming library conduit, I thought I would recreate the asynchronous chat server from Simon Marlow's book, Parallel and Concurrent Programming in Haskell. If you haven't read it yet, it's required read
Lost in Technopolis
Recently I was playing around with the core types in the conduit library (attempting to change leftovers so you could only unget values you had read), when I stumbled across a formulation of those types that lead to some interesting simplifications. Before I jump in, let’s review what any effectful streaming library should aim to accomplish. The basics are: Iterate over values within a structure,
Conduits vs. Pipes
Michael Snoyman released conduit-0.3 this week. The conduit package provides three datatypes that can be chained together: Source, Counduit and Sink. If you were to look at the source code, you will notice that there is a lot of overlap between these datatypes. In this post I'll show how these types can be combined into a single one, which is the idea used by the pipes package. Compare: data Sink
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Day 6: Conduit — Streamy Co-routines for Piping Together Computations
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vectorBuilder: packed-representation yielding for conduit - FP Complete