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| title: Reasonable Language Choice | ||
| spoiler: On TypeScript and ReasonML as JavaScript alternatives, ecosystems and trade-offs. | ||
| date: 2020-03-07T10:22:23.190Z | ||
| history: Verbose | ||
| --- | ||
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| Epistemic Effort: I spoke about it a few times and wanted to formalize my notes. | ||
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| I believe that the language choice isn't the most crucial choice in software development. Important problems translate fairly well between the languages, and the majority of developers I respect are polyglots. | ||
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| However, let me ponder the choice between ReasonML and TypeScript. I hope you'll find it interesting. | ||
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| --- | ||
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| I find ML family languages pleasing. Despite this, I couldn't recommend ReasonML to many teams. | ||
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| TypeScript is a nonromantic, and possibly unpleasant, but reasonable language choice. | ||
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| Let me explain. | ||
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| I work in the web ecosystem. The JavaScript ecosystem. | ||
| I build apps and libraries, which solve real, but fairly ordinary problems. I won't call it simple, but it's not really rocket science. I strive to do it well, aim for short feedback loop with correct, maintainable and cheap to produce code. | ||
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| ### Correctness | ||
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| I need correctness, so we reach for static type system. | ||
| Tests are not enough. I want to write about types. The person who reads my code can read about types, and see the bird's-eye view. | ||
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| [Tests are not enough]: https://css-tricks.com/types-or-tests-why-not-both | ||
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| You might be familiar with the famous quote "TypeError: undefined is not a function". | ||
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| I claim that writing strict functional TypeScript provides the same level of correctness and control over your codebase as ReasonML. | ||
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| I'd like to avoid expanding on it now, but what I mean by strict functional TypeScript is shortly: | ||
| - `compilerOptions.strict: true`. Avoid `any` and `!`. | ||
| - Prefers `head(array)` over `array[0]`. ([#11122]) | ||
| - Generous use of discriminated unions. | ||
| - Prefers libraries designed for TypeScript over JavaScript typed in DT. (fp-ts over lodash-fp or ramda) | ||
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| [#11122]: https://github.com/Microsoft/TypeScript/issues/11122#issuecomment-251686473 | ||
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| ### Maintainable | ||
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| #### Language "Quality" | ||
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| TypeScript fixes a lot of JavaScript problems (null >= 0 === true :rofl:), but it still inherits a big chunk of them. | ||
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| [null >= 0 === true]: https://blog.campvanilla.com/javascript-the-curious-case-of-null-0-7b131644e274 | ||
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| Adding methods to right-hand side of the assignment in setter is still possible and pn top of that it's a thing that really smart people seriously consider. | ||
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| [Adding methods to right-hand side of the assignment]: https://github.com/WICG/construct-stylesheets/issues/45#issuecomment-521224893 | ||
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| ReasonML certainly wins this competition by not being JavaScript. Pattern matching and Hindley-Milner type inference of ReasonML are beautiful things, but we don't even have to mention them. Not being JavaScript is enough. | ||
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| <small> | ||
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| One could respond: Git gud. Just learn JavaScript! Thing is, I have no intention to remember the quirks of JavaScript! I want to focus on delivering business value and this is just accidental complexity! I don't care that `{} + [] === 0`. If I wrote this, it was an accident, I didn't have my morning coffee. I want my tools to protect me and tell me "Yo dude, that's weird" with bright red squigglies. | ||
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| TypeScript is not meant to be pretty. It is designed for gradual migration of big JavaScript codebases. You can type some wildly dynamic code with a Turing complete type system. Is TS type system absurdly powerful? Yes. Can you write some hideous incomprehensible [conditional types] spaghetti in it? Yes. Does this result in excellent editor support and precise types even for weird dynamic patterns? Yes. Absolutely. | ||
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| [conditional types]: https://www.typescriptlang.org/docs/handbook/advanced-types.html#conditional-types | ||
| [Turing complete type system]: https://github.com/Microsoft/TypeScript/issues/14833 | ||
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| However, | ||
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| </small> | ||
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| #### Language Familiarity | ||
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| I believe that C-like syntax of JavaScript makes it a good language for beginners | ||
| There are legions of JavaScript developers. | ||
| Typed JavaScript. | ||
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| ### Cheap to produce | ||
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| I find the "Build or Install" decision interesting. (Build vs Buy / Make Or Buy) | ||
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| How much of our code should really be other people's code? The answer can be "all of it", if we're using no-code tools. It can also be "zero" if you're building a language or "next to none" for a library for building user interfaces. | ||
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| [language]: https://github.com/microsoft/TypeScript/blob/master/package.json#L132 | ||
| [UI framework]: https://github.com/facebook/react/blob/master/packages/react/package.json#L28-L31 | ||
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| For most web apps built in software houses, I believe the answer to be "as much as we're comfortable with". | ||
| Gluing together libraries that fix parts of your problem is a valid way to build a product. As is using no-code and gluing together entire products. It isn't as glorious as Real Man C++ Programming, but it puts the bread on the table. | ||
| More so, it allows to build better products in a limited time span. Time to swallow our pride, and stand on the shoulder of giants, my friend. | ||
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| [Real Man C++ Programming]: https://www.urbandictionary.com/define.php?term=C%2B%2B&defid=2583707#.XmO26-jht3E.twitter | ||
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| But hey! React has almost no dependencies, TypeScript and Mitt have exactly zero. | ||
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| We trade off control for time. | ||
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| Libraries need more control. Few kB of difference in bundle size or one corner case vulnerability is the difference between mass adoption and oblivion. | ||
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| Languages and OSes need even more control. | ||
| Fuchsia devs pin all dependencies to exact version by policy. React contains a purpose-built min heap implementation. | ||
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| [by policy]: https://fuchsia.dev/fuchsia-src/project/policy/external_dependencies | ||
| [min heap implementation]: https://github.com/facebook/react/pull/16245/files | ||
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| EMBED WITH RESPONSE https://twitter.com/imohitbhatia/status/1159932373955297280 | ||
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| It is important to notice the difference in scale. I mentioned projects which plan ahead for years instead of months. They aim to topple the giants. | ||
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| Summarizing: You're invited to a party. Is it appropriate to bring your friends? It depends. Are you the party person and the hosts clearly expect you to bring your squad ( | ||
| `redux-toolkit`)? Or do you live by the "Do One Thing And Do It Well" motto and you are expected to come alone? | ||
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| [Do One Thing And Do It Well]: https://en.wikipedia.org/wiki/Unix_philosophy#Do_One_Thing_and_Do_It_Well | ||
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| Going back to TypeScript and ReasonML. If you know you are going to compose your app from chunks of existing code, choosing a language with the bigger ecosystem is a good idea. | ||
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| How do the ecosystems of these two languages compare? | ||
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| As I am writing this, DefinitelyTyped has 10,669 contributors and 26,828 stars with a 0.4 contributors to stars ratio. [1] | ||
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| For comparison: | ||
| - Vue: 290 👩💻 and 158k ⭐ ▶️ 0.00182 ratio | ||
| - TypeScript: 448 👩💻 and 59k ⭐ ▶️ 0.00765 ratio | ||
| - ReasonML: 124 👩💻 and 8.6k ⭐ ▶️ 0.01455 ratio | ||
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| Look at the ratio! Four tenths! DefinitelyTyped is not a fun thing people star, because they like it. I hate contributing to DT! Yet, there are many brilliant libraries in the JavaScript ecosystem and I want to use them in my statically typed projects. | ||
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| There are 10 thousand people who introduce the best JavaScript libraries [2] to TypeScript. The sheer number is astonishing. There are more people who actively improve TypeScript ecosystem than people who declare that they like Reason! The numbers speak in favor of TypeScript. I realize that this is a cold argument and that I am betting for Goliath against David. | ||
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| <small> | ||
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| [1] State of the Octoverse reports different numbers. GitHub isn't clear what "contributor" means. I believe that repository pages report the number of commit authors, and the State of the Octoverse reports the number of issue authors. | ||
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| [State of the Octoverse]: https://octoverse.github.com/#top-and-trending-projects | ||
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| [2] Kind of. Many libraries "introduce themselves". JavaScript ecosystem is a superset of TypeScript ecosystem. Your favorite libraries you use in JavaScript might be written in TypeScript. Notable mentions: Jest, XState, VSCode, both Redux and MobX. | ||
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| </small> |