Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Parser Combinators
Search
yhkaplan
December 03, 2019
Programming
0
280
Parser Combinators
yhkaplan
December 03, 2019
Tweet
Share
More Decks by yhkaplan
See All by yhkaplan
Using the latest UICollectionView APIs
yhkaplan
0
2.5k
Swift and Concurrency: The Plan for World Domination
yhkaplan
0
180
Backend-Driven UI: Making Screens Dynamic
yhkaplan
1
1.7k
Migrating from UIKit to SwiftUI efficiently
yhkaplan
4
3.5k
Property Wrappers
yhkaplan
0
550
The Great Swift Migration
yhkaplan
1
4.1k
Speeding Up Your CI
yhkaplan
0
480
Automate All the Things
yhkaplan
4
2.4k
Other Decks in Programming
See All in Programming
PipeCDのプラグイン化で目指すところ
warashi
1
290
なぜ「共通化」を考え、失敗を繰り返すのか
rinchoku
1
670
Android 16KBページサイズ対応をはじめからていねいに
mine2424
0
240
AI駆動のマルチエージェントによる業務フロー自動化の設計と実践
h_okkah
0
220
オンコール⼊⾨〜ページャーが鳴る前に、あなたが備えられること〜 / Before The Pager Rings
yktakaha4
1
830
可変変数との向き合い方 $$変数名が踊り出す$$ / php conference Variable variables
gunji
0
100
What's new in AppKit on macOS 26
1024jp
0
150
Composerが「依存解決」のためにどんな工夫をしているか #phpcon
o0h
PRO
1
330
코딩 에이전트 체크리스트: Claude Code ver.
nacyot
0
880
新メンバーも今日から大活躍!SREが支えるスケールし続ける組織のオンボーディング
honmarkhunt
5
8.3k
#QiitaBash MCPのセキュリティ
ryosukedtomita
1
1.5k
High-Level Programming Languages in AI Era -Human Thought and Mind-
hayat01sh1da
PRO
0
840
Featured
See All Featured
ReactJS: Keep Simple. Everything can be a component!
pedronauck
667
120k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
29
9.6k
CSS Pre-Processors: Stylus, Less & Sass
bermonpainter
357
30k
GraphQLとの向き合い方2022年版
quramy
49
14k
The Myth of the Modular Monolith - Day 2 Keynote - Rails World 2024
eileencodes
26
2.9k
Building an army of robots
kneath
306
45k
Balancing Empowerment & Direction
lara
1
440
The Invisible Side of Design
smashingmag
301
51k
Adopting Sorbet at Scale
ufuk
77
9.5k
Rails Girls Zürich Keynote
gr2m
95
14k
Templates, Plugins, & Blocks: Oh My! Creating the theme that thinks of everything
marktimemedia
31
2.4k
Being A Developer After 40
akosma
90
590k
Transcript
Parser Combinators 1
Self Intro » Name: Joshua Kaplan » Interests: ! λ
" » Company: GMO Pepabo » Service: minne 2
What are Parser Combinators? 3
» Higher-order function that takes multiple parsers and /combines/ them
into a new parser » CS theory » Parsec, Haskell 4
In Swift struct Parser<A> { let run: (inout Substring) throws
-> A } 5
Characteristics » Monadic » Composable » Generic » Immutable 6
Use let int = Parser<Int> { input in let num
= input.prefix(while: { $0.isNumber }) guard let number = Int(num) else { throw ParserError.IntError.notANumber(num) } input.removeFirst(num.count) return number } 7
func removingLiteral(_ string: String) -> Parser<Void> { return Parser<Void> {
input in guard input.hasPrefix(string) else { throw ParserError.StringError.literalNotFound(string[...]) } input.removeFirst(string.count) } } 8
Higher order functions » map » flatMap (bind, >>=) »
zip 9
struct Coordinate { let x, y: Int } let str
= "1,2" let coordinateParser = zip( int, removingLiteral(","), int ).map { x, _, y in Coordinate(x: x, y: y) } let (coordinate, _) = try coordinateParser.run(str[...]) ▿ Coordinate - x: 1 - y: 2 10
func substring(while predicate: @escaping (Character) -> Bool) -> Parser<Substring> {
return Parser<Substring> { input in let p = input.prefix(while: predicate) input.removeFirst(p.count) return p } } 11
Let's make another parser! struct Person { let name: String;
let age: Int } let str = "name: John, age: 90" 12
Name and age parsers let nameParser = zip( removingLiteral("name: "),
substring(while: { $0.isLetter }) ).map { _, name in return String(name) } let ageParser = zip( removingLiteral("age: "), int ).map { _, age in return age } 13
Person parser let personParser = zip( nameParser, removingLiteral(", "), ageParser
).map { name, _, age in return Person(name: name, age: age) } let (person, _) = try personParser.run(str[...]) ▿ Person - name: "John" - age: 90 14
Comparison » By hand » Scanner 15
Why and when? 16
References » https://github.com/pointfreeco/episode-code- samples/tree/master/0064-parser-combinators-pt3 » https://talk.objc.io/episodes/S01E13-parsing- techniques » https://github.com/johnpatrickmorgan/Sparse »
https://github.com/davedufresne/SwiftParsec » https://github.com/thoughtbot/Argo » https://github.com/tryswift/TryParsec 17