Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Sign up for free
Menu
Search
Features
All features
Private URLs
Password Protection
Custom URLS
Scheduled publishing
Remove Branding
Restrict embedding
Deck Collections
Notes
Features
All features
Private URLs
Password Protection
Custom URLS
Scheduled publishing
Remove Branding
Restrict embedding
Deck Collections
Notes
Explore
Featured decks
Featured speakers
Programming
Technology
Storyboards
Explore
Featured decks
Featured speakers
Programming
Technology
Storyboards
Pricing
Search
Sign in
Sign up for free
Write better React (v3 ReasonReact)
Search
David Kopal
May 11, 2019
Technology
680
0
Share
Embed
Copy iframe code
Copy JS code
Copy link
Start on current slide
Write better React (v3 ReasonReact)
David Kopal
May 11, 2019
More Decks by David Kopal
See All by David Kopal
Use ReasonML in your React applications (RuhrJS 2018)
codinglawyer
2
310
Use Reason in your React applications
codinglawyer
3
610
Unleash the power of the higher-order components
codinglawyer
2
290
Other Decks in Technology
See All in Technology
GoCon2026 - Open Source, Open World
sanposhiho
2
950
2026-09-09 【sigma_ucj#1】Sigma を IaC 管理したい! / IaC for Sigma
civitaspo
0
100
AI活用の現在地、 ちゃんと見えてますか?/XPfest-2026
visional_engineering_and_design
0
170
Tab5をRubyで動くパソコンにする
kishima
2
280
アプリをもっと"iOSアプリっぽく"する小さな工夫 / Small Touches That Make Your App Feel More Like an iOS App
matsuji
1
170
AIオーケストレーションを活用した 開発ワークフローの設計と実践
bqnq
0
120
【視聴者参加型!】AWSセキュリティアンチパターンクイズ
syoshie
1
480
Bet AI Day 2026丨AIを「使う」から、AIが「働く」へ ― LayerXが進める「組織AI」の社会実装
layerx
PRO
3
2.9k
あるけみー式LTスライド作成術
alchemy1115
1
140
日経電子版を支えていく Kasane Design System/fec_fukuoka
nikkei_engineer_recruiting
0
350
20260912_スクフェス三河
kgnkhkr
0
160
Podは生きているのにGoだけが落ちる:GOGCとGOMEMLIMITで追うInvisible OOM Killの謎
tkc66buzz
1
240
Featured
See All Featured
Getting science done with accelerated Python computing platforms
jacobtomlinson
2
470
Building Experiences: Design Systems, User Experience, and Full Site Editing
marktimemedia
0
600
Gemini Prompt Engineering: Practical Techniques for Tangible AI Outcomes
mfonobong
2
520
Reality Check: Gamification 10 Years Later
codingconduct
0
2.3k
SEO in 2025: How to Prepare for the Future of Search
ipullrank
3
3.8k
10 Git Anti Patterns You Should be Aware of
lemiorhan
PRO
659
62k
RailsConf 2023
tenderlove
30
1.5k
Art, The Web, and Tiny UX
lynnandtonic
304
22k
How Software Deployment tools have changed in the past 20 years
geshan
1
34k
Self-Hosted WebAssembly Runtime for Runtime-Neutral Checkpoint/Restore in Edge–Cloud Continuum
chikuwait
0
780
Bash Introduction
62gerente
615
220k
XXLCSS - How to scale CSS and keep your sanity
sugarenia
249
1.3M
Transcript
Write better React with ReasonML David Kopal
@coding_lawyer codinglawyer.io learnReasonML.com I’m David Kopal
@coding_lawyer Who heard about ason?
@coding_lawyer
@coding_lawyer Who wants to write better React?
@coding_lawyer React isn’t a native JavaScript library
@coding_lawyer
@coding_lawyer Immutability
@coding_lawyer Immutability
@coding_lawyer Immutability
@coding_lawyer Immutability Functional programming
@coding_lawyer Immutability Functional programming
@coding_lawyer Immutability Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer Immutability Type system Functional programming
@coding_lawyer
@coding_lawyer semantics Javascript-like syntax
@coding_lawyer let fizzbuzz = (i) => switch (i mod 3,
i mod 5) { | (0, 0) => "FizzBuzz" | (0, _) => "Fizz" | (_, 0) => "Buzz" | _ => string_of_int(i) }; for (i in 1 to 100) { Js.log(fizzbuzz(i)) };
@coding_lawyer compiler
@coding_lawyer function fizzbuzz(i) { var match = i % 3
var match$1 = i % 5 if (match !== 0) { if (match$1 !== 0) { return String(i) } else { return 'Buzz' } } else if (match$1 !== 0) { return 'Fizz' } else { return 'FizzBuzz' } } for (var i = 1; i <= 100; ++i) { console.log(fizzbuzz(i)) } let fizzbuzz = (i) => switch (i mod 3, i mod 5) { | (0, 0) => "FizzBuzz" | (0, _) => "Fizz" | (_, 0) => "Buzz" | _ => string_of_int(i) }; for (i in 1 to 100) { Js.log(fizzbuzz(i)) };
@coding_lawyer JavaScript interop
@coding_lawyer
@coding_lawyer Reason is compatible with React
@coding_lawyer Reason is compatible with React React was developed for
Reason
@coding_lawyer adjusted JavaScript to React’s needs
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer semantics Javascript-like syntax
@coding_lawyer safer React
@coding_lawyer “[Reason] is the best way to take React to
the next level” Jordan Walke, creator of Reason, React
@coding_lawyer Tic Tac Toe
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer components
@coding_lawyer stateless component
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer [@react.component] let make = (~title) !=> <div> <div className=“title">
{React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer [@react.component] let make = (~title) !=> <div> <div className=“title">
{React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer [@react.component] let make = (~title) !=> <div> <div className=“title">
{React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer [@react.component] let make = (~title) !=> <div> <div className=“title">
{React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer stateful component
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer React.useReducer( (state: state, action: action) !=> switch (action) {
| Restart !=> initialState | ClickSquare((id: string)) !=> let updatedBoard = updateBoard( state.board, state.gameState, id); let updatedGs = checkGameState3x3( updatedBoard, state.board, state.gameState); { board: updatedBoard, gameState: updatedGs, };}, …);
@coding_lawyer React.useReducer( (state: state, action: action) !=> switch (action) {
| Restart !=> initialState | ClickSquare((id: string)) !=> let updatedBoard = updateBoard( state.board, state.gameState, id); let updatedGs = checkGameState3x3( updatedBoard, state.board, state.gameState); { board: updatedBoard, gameState: updatedGs, };}, …);
@coding_lawyer [@react.component] let make = () !=> { let (state,
dispatch) = React.useReducer( (state: state, action: action) !=> switch (action) { | Restart !=> … | ClickSquare((id: string)) !=> … }, { board: […], gameState: Playing(Cross) }, ); <div className="game"> <Board state onRestart={_evt !=> dispatch(Restart)} onMark={id !=> dispatch(ClickSquare(id))} !/> !</div>;};
@coding_lawyer old syntax (v2) vs new syntax (v3)
@coding_lawyer [@react.component] let make = (~title) !=> <div> <div className=“title">
{React.string(title)} !</div> <Game !/> !</div>; new syntax (v3)
@coding_lawyer let component = ReasonReact.statelessComponent("App"); let make = (~title, _children)
=> { ...component, render: _self => <div> <div className=“title"> (ReasonReact.string(title)) </div> <Game /> </div>, }; old syntax (v2)
@coding_lawyer let component = ReasonReact.statelessComponent("App"); let make = (~title, _children)
=> { ...component, render: _self => <div> <div className=“title"> (ReasonReact.string(title)) </div> <Game /> </div>, }; old syntax (v2) var component = ReasonReact.statelessComponent("App"); function make(title, _children) { return !/* record !*/[ !/* debugName !*/component[!/* debugName !*/0], !/* reactClassInternal !*/component[!/* reactClassInternal !*/1] !/* handedOffState !*/component[!/* handedOffState !*/2], !/* willReceiveProps !*/component[!/* willReceiveProps !*/3], !/* didMount !*/component[!/* didMount !*/4], !/* didUpdate !*/component[!/* didUpdate !*/5], !/* willUnmount !*/component[!/* willUnmount !*/6], !/* willUpdate !*/component[!/* willUpdate !*/7], !/* shouldUpdate !*/component[!/* shouldUpdate !*/8], !/* render !*/(function (_self) { return React.createElement( “div", undefined, React.createElement( "div", { className: “title" }, title), React.createElement(Game.make, { }) ); }), !/* initialState !*/component[!/* initialState !*/10], !/* retainedProps !*/component[!/* retainedProps !*/11], !/* reducer !*/component[!/* reducer !*/12], !/* jsElementWrapped !*/component[!/* jsElementWrapped !*/13] ]; } exports.component = component; exports.make = make;
@coding_lawyer function App(Props) { var title = Props.title; return React.createElement(
“div", undefined, React.createElement( "div", { className: “title" }, title), React.createElement(Game.make, { }) ); } var make = App; exports.make = make; new syntax (v3) [@react.component] let make = (~title) !=> <div> <div className=“title"> {React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer const App = (Props) !=> ( <div> <div className="title">
{React.string(Props.title)} !</div> <Game !/> !</div>; ) var make = App; exports.make = make; new syntax (v3) [@react.component] let make = (~title) !=> <div> <div className=“title"> {React.string(title)} !</div> <Game !/> !</div>;
@coding_lawyer var component = ReasonReact.statelessComponent("App"); function make(title, _children) { return
!/* record !*/[ !/* debugName !*/component[!/* debugName !*/0], !/* reactClassInternal !*/component[!/* reactClassInternal !*/1], !/* handedOffState !*/component[!/* handedOffState !*/2], !/* willReceiveProps !*/component[!/* willReceiveProps !*/3], !/* didMount !*/component[!/* didMount !*/4], !/* didUpdate !*/component[!/* didUpdate !*/5], !/* willUnmount !*/component[!/* willUnmount !*/6], !/* willUpdate !*/component[!/* willUpdate !*/7], !/* shouldUpdate !*/component[!/* shouldUpdate !*/8], !/* render !*/(function (_self) { return React.createElement( “div", undefined, React.createElement( "div", { className: “title" }, title), React.createElement(Game.make, { }) ); }), !/* initialState !*/component[!/* initialState !*/10], !/* retainedProps !*/component[!/* retainedProps !*/11], !/* reducer !*/component[!/* reducer !*/12], !/* jsElementWrapped !*/component[!/* jsElementWrapped !*/13] ]; } exports.component = component; exports.make = make; const App = (Props) !=> ( <div> <div className="title"> {React.string(Props.title)} !</div> <Game !/> !</div>; ) var make = App; exports.make = make; new syntax (v3) old syntax (v2)
@coding_lawyer type system
@coding_lawyer clearer and safer code
@coding_lawyer superior to Flow and TypeScript
@coding_lawyer type inference
@coding_lawyer !/* type inference by the compiler !*/ let plus
= (a, b) !=> a + b
@coding_lawyer !/* type inference by the compiler !*/ let plus
= (a, b) !=> a + b !/* (int, int) !=> int !*/
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw; type player = | Cross | Circle;
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw; type player = | Cross | Circle;
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw; type player = | Cross | Circle;
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw; type player = | Cross | Circle;
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw; type player = | Cross | Circle;
@coding_lawyer
@coding_lawyer pattern matching
@coding_lawyer Game Board App BoardRow Square
@coding_lawyer React.useReducer( (state: state, action: action) !=> switch (action) {
| Restart !=> initialState | ClickSquare((id: string)) !=> let updatedBoard = updateBoard( state.board, state.gameState, id); let updatedGs = checkGameState3x3( updatedBoard, state.board, state.gameState); { board: updatedBoard, gameState: updatedGs, };}, …);
@coding_lawyer let updateBoard = (board: board, gameState: gameState, id) =>
board |> List.mapi((ind: int, row: row) => row |> List.mapi((index: int, value: field) => string_of_int(ind) ++ string_of_int(index) === id ? switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty } : value ) );
@coding_lawyer let updateBoard = (board: board, gameState: gameState, id) =>
board |> List.mapi((ind: int, row: row) => row |> List.mapi((index: int, value: field) => string_of_int(ind) ++ string_of_int(index) === id ? switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty } : value ) );
@coding_lawyer type field = | Empty | Marked(player); type gameState
= | Playing(player) | Winner(player) | Draw;
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) | (_, _) => Empty }
@coding_lawyer /* determines the value of the clicked square */
switch (gameState: gameState, value: field) { | (Playing(_), Marked(_)) => value | (Playing(player), Empty) => Marked(player) /* | (_, _) => Empty */ }
@coding_lawyer
@coding_lawyer switch ( getWinner(flattenBoard, head), gameEnded(flattenBoard), tail, ) { |
(Cross, _, _) => Winner(Cross) | (Circle, _, _) => Winner(Circle) | (_, true, []) => Draw | (_, false, []) => whosPlaying(gameState) | _ => check(tail) };
@coding_lawyer switch (match$1) { case 0 : return /* Winner
*/Block.__(1, [/* Cross */0]); case 1 : return /* Winner */Block.__(1, [/* Circle */1]); case 2 : if (match$2) { if (tail) { _rest = tail; continue ; } else { return /* Draw */0; } } else if (tail) { _rest = tail; continue ; } else { return whosPlaying(gameState); } }
@coding_lawyer Why should you use React in Reason?
@coding_lawyer Reason is compatible with React's principles
@coding_lawyer strong type system
@coding_lawyer pattern matching
@coding_lawyer functional programming features
@coding_lawyer JavaScript-like syntax React friendly
@coding_lawyer Learn ReasonML! learnReasonML.com
@coding_lawyer codinglawyer.io @coding_lawyer
@coding_lawyer Thank You
@coding_lawyer codinglawyer.io @coding_lawyer learnReasonML.com