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Daniel Fry

@danfrydev

Software engineer in London. TypeScript and AI. VP SWE @jpmorgan @chase_uk

 London
danfry.dev
Joined February 2022
  • Tweets126
  • Following1.8K
  • Followers430
bun.sh vs create-react-app 🤯 #bunjs
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How it works and its limits: github.com/danfry1/typescrip… Playground: typescriptlang.org/play?#cod…
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TypeScript can check a credit card number's checksum (Luhn). One wrong digit is a compile error, no runtime code.
TypeScript code in an editor. Recursive types reverse a card number's digits, double every second one and add them up, and the number passes if the total ends in 0. A card() function uses the result: three valid card numbers compile, and the same numbers with one digit changed show red squiggles and the error "Argument of type ... is not assignable to parameter of type 'never'".

ALT TypeScript code in an editor. Recursive types reverse a card number's digits, double every second one and add them up, and the number passes if the total ends in 0. A card() function uses the result: three valid card numbers compile, and the same numbers with one digit changed show red squiggles and the error "Argument of type ... is not assignable to parameter of type 'never'".

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Replying to @thymikee
@thymikee
Image from Daniel Fry (@danfrydev)
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Replying to @thymikee
Needed this! Great work @thymikee and team 🚀
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How it works and its limits (string literals only, hex only): github.com/danfry1/typescrip… Playground: typescriptlang.org/play?#cod…
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#ggg is now a compile error. TypeScript types can check hex colors, alpha included, no runtime code.
Image from Daniel Fry (@danfrydev)
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waxon.danfry.dev brew install danfry1/tap/waxon (also Nix, Scoop and Go) github.com/danfry1/waxon
waxon: Spotify from the home row

waxon: Spotify from the home row

A Spotify client for the terminal with vim keys, album art and synced lyrics.

waxon.danfry.dev
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I built a Spotify client for the terminal. waxon has vim keys, album art and synced lyrics, and it can play music by itself or drive the Spotify app. Free and open source. Try the demo in your browser 👇
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Replying to @jmeistrich
Fast React Native on desktop 🚀 nice one
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Replying to @SunWeatherMan
@SunWeatherMan
🤖 Made with AI
Image from Daniel Fry (@danfrydev)
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I read through every note and routine before using a Grok Bot template, and I'll probably keep doing it. But does @bot check templates for anything sketchy, or should everyone be reviewing them before they import?
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Amazon's own page on it (ACR): amazon.com/gp/help/customer/… There's a toggle in Settings > Preferences > Privacy Settings too. I disabled the package as well: adb shell pm disable-user --user 0 com.amazon.tv.acr
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My Fire TV was watching what I watch. A built-in service fingerprints what's on screen, even through HDMI, and sends Amazon the channels, shows and ads you watched. Joined the debloat trend and switched it off, plus 28 other packages, over ADB.
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Replying to @danylo_pravda
Yes, every member. The import is typed with exactly the classes in the file, so if variant is "primary" | "outline" and there's no .outline, styles[variant] is a compile error. A plain string errors too (with strict on), since there's no index signature.
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Typo a CSS module class and tsc fails. No codegen, no .d.ts files. typed-css-imports uses content mappers from the TypeScript 7.1 beta, so styles.buttn is an error in your editor and in CI. Completions update as you type in the CSS file. Sass works too. pnpm add -D typed-css-imports [email protected] github.com/danfry1/typed-css…
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Thanks @StuffSA and @trentmeikle for the lovely write-up! Iconic South African moments, ten seconds each. Go for gold on all of them. It's free, no sign-up. Got a moment you'd add? Drop it in the suggestion box. lekkamoments.com
Lekka Moments

Lekka Moments

A pixel-art album of South African moments. One button, about ten seconds each.

lekkamoments.com
Stuff South Africa (@StuffSA) profile pictureStuff South Africa
@StuffSAOct 25
Lekka Moments is a lekker little web game celebrating South Africa's most iconic moments (Created by @danfrydev) stuff.co.za/2026/10/25/lekka…
Lekka Moments is a lekker little web game celebrating South Africa's most iconic moments - Stuff...

Lekka Moments is a lekker little web game celebrating South Africa's most iconic moments - Stuff...

Stuff is always on the lookout for decent web games to keep us busy during the workday, and SA-made Lekka Moments fits that bill. Created...

stuff.co.za
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how it works + limits: github.com/danfry1/typescrip… playground: typescriptlang.org/play?#cod…
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building on this: port 65536 is now a compile error. no runtime check, no recursion 🧱
TypeScript code defining a Port type that accepts 1 to 65535, digit by digit, using template literal types. listen(3000) and listen(65535) compile, while listen(65536) and listen(0) are underlined in red as errors.

ALT TypeScript code defining a Port type that accepts 1 to 65535, digit by digit, using template literal types. listen(3000) and listen(65535) compile, while listen(65536) and listen(0) are underlined in red as errors.

Daniel Fry (@danfrydev) profile pictureDaniel Fry
@danfrydevOct 20
turns out TypeScript types can enforce a min and max string length too
TypeScript code: a Username template literal type built from 3 required one-character placeholders and 5 optional ones, so only strings of 3 to 8 characters are allowed. "dan" and "danfry" compile; "df" (too short) and "danfrydev" (too long) are errors.

ALT TypeScript code: a Username template literal type built from 3 required one-character placeholders and 5 optional ones, so only strings of 3 to 8 characters are allowed. "dan" and "danfry" compile; "df" (too short) and "danfrydev" (too long) are errors.

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try it in the playground: typescriptlang.org/play/#cod…
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