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
Boxed: bringing algebraic types to TypeScript
Search
Matthias Le Brun
March 27, 2024
Technology
0
67
Boxed: bringing algebraic types to TypeScript
Matthias Le Brun
March 27, 2024
Tweet
Share
More Decks by Matthias Le Brun
See All by Matthias Le Brun
(why the hell did I) build a GraphQL client for the browser
bloodyowl
0
24
leveraging (algebraic data) types to make your UI rock @ jsheroes
bloodyowl
0
260
Leveraging (algebraic data) types to make your UI rock solid
bloodyowl
0
370
La drôle d'histoire de JavaScript
bloodyowl
0
330
Healthy Code Collaboration
bloodyowl
0
240
Simplify your UI management with (algebraic data) types
bloodyowl
0
780
Simplify your UI management with (algebraic data) types
bloodyowl
1
500
Migrating a large Reason+React codebase to hooks
bloodyowl
0
530
Third Party Hell (BestOfWeb)
bloodyowl
0
550
Other Decks in Technology
See All in Technology
OCI IAM Identity Domains Entra IDとの認証連携設定手順 / Identity Domain Federation settings with Entra ID
oracle4engineer
PRO
1
1.3k
フォーイット_エンジニア向け会社紹介資料_Forit_Company_Profile.pdf
forit_tech
1
1.7k
Log Analytics を使った実際の運用 - Sansan Data Hub での取り組み
sansantech
PRO
0
170
役員・マネージャー・著者・エンジニアそれぞれの立場から見たAWS認定資格
nrinetcom
PRO
5
6.9k
AIエージェント時代のエンジニアになろう #jawsug #jawsdays2025 / 20250301 Agentic AI Engineering
yoshidashingo
9
4.4k
Amazon Bedrock Knowledge basesにLangfuse導入してみた
sonoda_mj
2
260
User Story Mapping + Inclusive Team
kawaguti
PRO
3
600
生成AI×財務経理:PoCで挑むSlack AI Bot開発と現場巻き込みのリアル
pohdccoe
1
850
生成AIがローコードツールになる時代の エンジニアの役割を考える
khwada
0
350
x86-64 Assembly Essentials
latte72
4
760
MLflowはどのようにLLMOpsの課題を解決するのか
taka_aki
0
160
Platform Engineeringで クラウドの「楽しくない」を解消しよう
jacopen
4
290
Featured
See All Featured
Making the Leap to Tech Lead
cromwellryan
133
9.1k
Optimizing for Happiness
mojombo
377
70k
Why You Should Never Use an ORM
jnunemaker
PRO
55
9.2k
Building Your Own Lightsaber
phodgson
104
6.3k
No one is an island. Learnings from fostering a developers community.
thoeni
21
3.2k
StorybookのUI Testing Handbookを読んだ
zakiyama
28
5.5k
Navigating Team Friction
lara
183
15k
What's in a price? How to price your products and services
michaelherold
244
12k
Helping Users Find Their Own Way: Creating Modern Search Experiences
danielanewman
29
2.5k
Designing Experiences People Love
moore
140
23k
How to train your dragon (web standard)
notwaldorf
91
5.9k
The Power of CSS Pseudo Elements
geoffreycrofte
75
5.5k
Transcript
Boxed
Matthias Le Brun @bloodyowl lead engineering manager chief shitpost office
the easiest way to provide banking features (accounts, payments, cards…) we're hiring! @
None
None
None
None
PREVIOUSLY ON Matthias tries to convert people to FP
Algebraic Data Types yay
type State = { data?: Data; error?: Error; };
type State = { data?: Data; error?: Error; }; type
Result<Data> = | Ok<Data> | Error<Error>; error data ERROR NULL NULL DATA NULL NULL ERROR DATA
{ data: null; error: null; };
type Result<Data> = | Ok<Data> | Error<Error>;
type State = { data?: Data; error?: Error; }; type
Result<Data> = | Ok<Data> | Error<Error>; state ERROR DATA
API response API response
API response API response
type State = { data?: Data; error?: Error; }; type
Result<Data> = | Ok<Data> | Error<Error>; 2 2 1 1 4 2 x = + =
Algebra it's just basic math™
+ x
quiz 157 x 8341 = ?
quiz 999 + 1 = ?
union types
monads functors
functor
monad
[1, 2, 3].map(x => x * 2) // [2, 4,
6] [1, 2, 3].flatMap(x => [x, x * 2]) // [1, 2, 2, 4, 3, 6]
map: <A, B>(T<A>, (a: A) => B) => T<B>: flatMap:
<A, B>(T<A>, (a: A) => T<B>) => T<B>;
None
null & undefined are bad
errors aren't always exceptions
promises were made the wrong way in JS
promises were made the wrong way in JS
promises were made the wrong way in JS
promises were made the wrong way in JS
THAT WAS Matthias tries to convert people to FP NOW
LET'S TALK ABOUT BOXED
✨ new job ✨ 2022
«we use TypeScript»
None
let's look at the ecosystem™
fp-ts
pipe( token, TaskEither.bindW("user", getTokenFromUser), TaskEither.bindW("project", getProject), TaskEither.chainW(getMembership), ) no autocomplete
on current value
pipe( token, TaskEither.bindW("user", getTokenFromUser), TaskEither.bindW("project", getProject), TaskEither.chainW(getMembership), x => {}
) need to inspect argument for type
pipe( token, TaskEither.bindW("user", getTokenFromUser), TaskEither.bindW("project", getProject), TaskEither.chainW(getMembership), x => {}
) need to inspect argument for type not a good DX
export declare const chainFirstTaskK: <A, B>(f: (a: A) = >
T.Task<B>) = > <E>(first: TaskEither<E, A>) = > TaskEither<E, A> ah just what I was looking for
we've looked at the ecosystem™
«let's try to make these types work with a good
DX in a structurally typed language» — me, allegedly drunk
structural typing
class Some<A> {} class None {} const value: Some<string> =
new None();
what we need → good DX → interop with ts-pattern
→ fast
what we needed → chaining API → autocomplete → less
imports
1st iteration: naive wanted the types to be opaque but
safe
1st iteration: naive discriminator in TS (aka poor man's nominal
types)
1st iteration: naive and we're storing the state in the
class instance
None
1st iteration: naive wanted the types to be opaque but
safe
1st iteration: naive wanted the types to be opaque but
safe
2nd iteration: anger
2nd iteration: anger
2nd iteration: anger
2nd iteration: anger
3rd iteration: make it fast
initial release
initial release
type Option<A> = Some<A> | None;
type Result<A, E> = Ok<A> | Error<E>;
type AsyncData<A> = | NotAsked | Loading | Done<A>;
Future<A>; better promises™ cancellable monadic leaves error state to Result
const parsed = input != null ? parseInput(input) : undefined;
const transformed = parsed != null ? transform(parsed) : undefined; const printed = transformed != null ? print(transformed) : undefined; const value = printed != null ? prettify(printed) : "fallback"; input .map(parseInput) .flatMap(transform) .map(print) .map(prettify) .getWithDefault("fallback");
user-testing
None
insights people need human-written docs → we doubled down on
examples & added search
insights don't try to replicate another language → give good
defaults for TS
Result< Data, ServerError > Result< A, ServerError | FinalizeError >
insights people are familiar with just a few data types
→ reduce confusion
insights people can be docs-first or type-first → experience needs
to be good for both
insights readability matters → chaining API was the way to
go
insights mapping on existing JS knowledge helps → if it
exists, name it the same way
insights pipe() syntax had impact on the runtime → expressiveness
is important
4th iteration implement the feedback rename some methods update some
defaults
5th iteration: what the actual fu
5th iteration: what the actual fu
recently fix the errors
recently improved perf by 2x to 10x
recently improved perf by 2x to 10x blazing fast certi
fi ed™ ⚡
Boxed → github.com/swan-io/boxed → swan-io.github.io/boxed
None
$ yarn add @swan-io/boxed
Matthias Le Brun @bloodyowl we're still hiring thank you! 🙏