@danfrydev

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

 London
danfry.dev
Joined February 2022
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  • Followers421
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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
@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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how it works + limits: github.com/danfry1/typescrip…
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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.

Daniel Fry
@danfrydevSep 27
turns out TypeScript types can enforce an exact string length
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Replying to @danfrydev @ctatedev @theo @boshen_c @jarredsumner
repo if you'd rather dig in there: github.com/danfry1/ts-checke…

GitHub - danfry1/ts-checker-bench: Speed, memory and diagnostics of TypeScript type checkers on...

Speed, memory and diagnostics of TypeScript type checkers on real projects, with the raw output behind every number - danfry1/ts-checker-bench

github.com
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cc @ctatedev @theo @boshen_c @jarredsumner if anything's set up wrong for your tool let me know and i'll fix it and rerun
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all on one m5, so i'd love to see how it holds on other machines. commands to rerun are on the site ts-checker-bench.danfry.dev

ts-checker-bench

How long a full TypeScript type check takes with tsgo, tsc-ts, tsc-rs, tsrs and bun, on VS Code, Outline and type-fest, and whether they report the same errors.

ts-checker-bench.danfry.dev
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errors: tsc-ts matched tsgo byte for byte on all three. bun printed the same error lines plus its own summary tsc-rs and tsrs report 1 extra on outline and 10 on vscode, and the 7.1-dev builds they port report the same. so that comes from 7.1, not the ports
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tsgo 7.0.2 as the reference, plus tsc-ts, tsc-rs, tsrs and bun check type-fest, outline and vscode, each pinned to a commit, fresh process every run, no incremental cache tsc-ts 0.0.4 and tsrs 0.18 shipped today, after this ran. rerun with those coming
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Built an open benchmark off the back of this: 5 typescript checkers, 3 real projects, raw output behind every result Controlled numbers come in under my quick first run. tsc-ts is 4.5x faster than tsgo on type-fest at defaults, 3.4x with both at 10 threads. ts-checker-bench.danfry.dev
Malte Ubl
@cramforceOct 18
TypeScript is 6 times faster than go[*]
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Replying to @CARLOSZIEGLER @cramforce
The errors matched tsgo 7.0.2 byte for byte on type-fest, outline and vscode with tsc-ts 0.0.3, clean and with errors planted on purpose. Early days but that's a good sign
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Daniel Fry retweeted
Kit Langton
@kitlangtonOct 18
hey. here's a little demo of the most meaningful improvement to my productivity since speech-to-text.
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Replying to @cramforce
ran the new tsc-ts against tsgo 7.0.2 on type-fest tsgo: 18.3s tsc-ts: 3.0s identical errors too, even with 6 checks broken on purpose. tsgo with 8 checkers gets to 13.6s so it's not just threads
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Replying to @tavus
Impressive work, but I can't get past the worry that technology like this makes life a lot easier for scammers and bad actors. What are the use cases you're most excited about?
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Replying to @techsavvytravvy
the key is `"" & String` vs `"" & {}`. TS folds `"" & {}` away, so the last D swallows the rest. `"" & String` stays a real placeholder and pins the end, so "12345678" fails and "1234" works (no leading zero needed) side by side: typescriptlang.org/play/?#co…
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Replying to @JitPackJoyride
thanks for sharing Ajit, this looks great!🦾
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another use: Ethereum addresses vs hashes (the case @MicahZoltu asked for in TypeScript issue #52243). Address = exactly 40 hex chars, Hash = exactly 64, so mixing them up is a compile error. no brands, no runtime code. playground: typescriptlang.org/play/?#co…
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try it in the playground: typescriptlang.org/play/?#co…
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xitter.cf/techsavvytravvy/status… builds on @techsavvytravvy's non-empty string trick. his gives you a minimum length, the `"" & String` end marker gives you an exact one.
trav
@techsavvytravvyJul 24
i found a way to represent a non-empty string without branded types and without using `any`
TypeScript code defining a NonEmptyString type that only accepts strings with at least one character, without using branded types or `any`. The example assigns a normal string successfully, then shows an empty string assignment marked as a type error. Below, a Zod schema builds the same rule at runtime with z.string().refine(...), checking that the string length is greater than zero and returning the message string must contain at least one character.

ALT TypeScript code defining a NonEmptyString type that only accepts strings with at least one character, without using branded types or `any`. The example assigns a normal string successfully, then shows an empty string assignment marked as a type error. Below, a Zod schema builds the same rule at runtime with z.string().refine(...), checking that the string length is greater than zero and returning the message string must contain at least one character.

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