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Comment by reichertjalex | Hacker News Reader

I remember having mixed feelings about Sorbet when I first joined Stripe in late 2018, but by the time I left, I found it indispensable. Especially after the VS Code extension was released internally... holy crap, that made such a huge difference (vs having CI fail 20 mins after pushing up a PR because you forgot to run the typechecker script ahead of time, ugh).

This article also made me laugh, because it reminded me of one of my small pet peeves about the Ruby codebase at Stripe: the fact that you would often find `merchant`, `account`, `invoice`, etc used as method parameters that represented the _ID_ of the resource rather than the resource itself. So Sorbet definitely helped with that, but it also could've been nice to just write `invoice_id` instead... :P

Makes me nostalgic though, good times!

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This is exactly how I felt when I was first forced to use TypeScript instead of JavaScript, but I can't even tell you the number of hours it has saved me. Now, years later, I can't stand using regular JavaScript, and would never recommend it for any project that will be beyond a toy.

I use Elm but not Typescript. I also write plain javascript intensively. I've seen languages adding static type layer after the fact they are dynamic type. They never end well, lots of edge case here and there, it becomes a problem rather than helper. Static type lang needs to think from start how they will compose nicely, what's pure, what's effect etc. However, the ship has sailed, I don't actually want to debate on this, because web tech is becoming a cult. (the last phrase added for downvote bait, lets do that!)

> I don't actually want to debate on this, because web tech is becoming a cult

Your critique of dynamic languages adding types and failing would be more understandable if you mentioned some examples or explained what Typescript got wrong.

.Net CodeContracts were this for me, but that was never fast. C# is a statically-typed language, so what kind of types could you further add to it? As a trivial example, maybe you want to ensure that `invoice_id` consists of at least 20 characters. CodeContracts would then statically attempt to prove that assertion for you. They had meticulously annotated the entirety of the .Net stdlib, and those annotations were spot-on.

This obviously helps with things like `null`.

It completely changed the way I code. You have to think a little bit more about how you structure your code if you plan to hand it off to a theorem prover. I unlearned several bad habits (I unlearned even more with Rust).

CodeContracts were a horrible hammer that people abused to not have to create proper types for things like an invoice id.

If you have a type system then you should leverage it, not bolt on something extra

What bad habits did you unlearn?

> the fact that you would often find `merchant`, `account`, `invoice`, etc used as method parameters that represented the _ID_ of the resource rather than the resource itself

I've encountered a few Rails projects in the wild that do this. One solution is to make liberal use of the `to_param` method. This method converts objects to strings that are intended for use in URLs. Of particular note, it's the identity function for strings and numbers, but returns `.id.to_s` for ActiveRecord models. Using this within definitions makes your function polymorphic for whether it accepts a model or an id.

If you do this widely, would probably be best to monkey-patch in your own `to_id` method.

Pretty much every model/resource has a `token` field, so we just call `invoice.token`, which is always a string.

I also joined Stripe in 2018, and thought Sorbet was a waste of time. I quickly changed my mind when I realized how many incidents it prevented. Now I want types for :allthethings!

Is there anything you can think to say to convince the old you? I have a few friends who haven’t yet seen the typing light.

I also think Stripe’s API (external) should not be moving ids and objects. Given some payload in which ‘account_id’ is always present and ‘account’ may be the object (using ‘expand’ IIRC?) or not makes a lot more sense to me.

My experience has been that the people opposed to types won't be convinced to start liking them by anything you can tell them or have them read. In all of the cases where I've seen Sorbet be adopted, the process looked like this:

1. Ambitious team who wants types does work to get the initial version passing in CI. Importantly, it's only checking at `# typed: false`, which basically only checks for missing constants and syntax errors.

2. That initial version sits silently in the codebase over a period of days or weeks. If new errors are introduced, it pings the enthusiastic Sorbet adoption team; they figure out whether it caught a real bug or whether the tooling could be improved. It does not ping the unsuspecting user yet.

3. Repeat until the pings are only high-signal pings

4. Turn Sorbet on in enforcing mode in CI. It's still only checking at `# typed: false` everywhere, but now individual teams can start to put `# typed: true` or higher in the files they care about.

5. Double check that at this point it's easy to configure whatever editor(s) your team uses to have Sorbet in the editor. Sorbet exposes an LSP server behind the `--lsp` flag, and publishes a VS Code extension for people who want a one-click solution.

6. Now the important part: show them how good Sorbet is, don't tell them. Fire up Sorbet on your codebase, delete something, and watch as the error list populates instantly. Jump to definition on a constant. Try autocompleting something.

In my experience trying to bring static types to Ruby users, seeing is really believing, and I've seen the same story play out in just about every case.

One final note: be supportive. Advertise one place for people to ask questions and get quick responses. Admit that you will likely be overworked for a bit until it takes off. But in the long run as it spreads, other teammates will start to help out with the evangelism as the benefits spread outward.

Thanks for this thoroughly practical advice -- evangelizing types inside Stripe must have been quite the journey! Been following since Dmytro and Paul's talk @ strangeloop.

Interestingly enough, I don't recall there ever being much pushback against static types at Stripe. The "evangelizing" work was more organizational: convincing people that yes, it is possible to build a production-ready type checker in 6-9 months[1], and then staff a team long term to continue improving it. I was at Stripe during that time, but on a different team, so I can't speak too much to the process.

Luckily I think Stripe is a well-functioning org with smart and reasonable leaders—much easier to present that case than e.g., trying to win debates on static vs dynamic typing on the internet!

[1] https://sorbet.run/talks/StrangeLoop2018/#/28

This process is near identical to the ones I went through to introduce Flow (initially) then Typescript (later on) for a number of projects I've worked on over the past few years.

Nowadays, its extremely rare for me to come across projects that don't use Typescript already!

I haven't yet seen the typing light, so maybe my perspective might spawn some replies that could help.

I understand that types are helpful, especially within the context of learning new code (both as a new dev, and more easily understanding new code written by your team), but my hesitation to "jump ship" to them comes from weighing all the "boilerplate" code necessary to get them working versus the tangible benefits I feel they'd give.

To that end, maybe enumerating over the benefits for your friends (ideally more specifically than just "fewer bugs" or "easier to read/write") might tilt the scale more towards using them.

The article shows some good examples of problems that types solve, but many of them could also be "fixed" with better naming schemes, standardizations, and/or refactors -- and then wouldn't also be littered with type annotations (which take up 50% of the code in their example, [1], where I've also added a couple other easy-to-understand "solutions" with less cruft.

IMO, most of the typing syntax in their examples is distracting from the actual code -- especially when just writing better or more standardized code (which you still need to do with types) would make the typing syntax, again IMO, less necessary.

[1] https://sorbet.run/#%23%20typed%3A%20true%0Aextend%20T%3A%3A...

Yeah unfortunately this is one of the problems, bolting on the types rarely works as well as it does for Typescript (looks quite natural to me).

In Haskell for example, writing signatures is actually both unnecessary (they will be inferrable, most of the time so it's basically only for humans to read) and a net positive (they fit well prose wise and you can use them as documentation) but that's a harder hill to climb.

I do want to note that one big advantage of specifying signatures is that now your IDE can help you when using the functions and detect when something is going wrong.

Maybe "no more trying to figure out what the input/output of a function that you didn't write is supposed to be" would be a draw?

What are some examples of where types have saved you? I mean, I can imagine some, but are there any good blog posts or have an example yourself?

I've moved on from Ruby to Elixir and we use typespecs at my current job, but I still never do in any of my own code. Elixir does have a way to do type hinting which I do use and appreciate when appropriate. So I'm not "against" types and like the idea in theory, but I've never really felt the pain.

The most tangible argument I've bought is that types help out in a huge codebase. I can definitely see this. This is really solving a social problem, of course, because on smaller teams, it's much easier to enforce coding standards, especially if you follow XP and pair all the time. For example, in large dynamic codebases I've worked on, calling something `object` when it really means `object_id` would never fly. Variables and functions always have to be full words describing exactly what they do. Functions are only ever allowed to return one type. And of course everything is thoroughly tested. Of course I understand that not all these things are practiced everywhere and nor do they need to be. But for me that has always made for incredibly readable code.

I'm writing this just to give the perspective of a dynamic weenie and maybe looking to be convinced a little more? I also know three incredibly good programmers with 20-50 years experience each who all wrote in typed languages for years and then couldn't be happier not to have types when they moved to Ruby. So ya, I dunno what I'm expecting here, but mostly offering my perspective.

But the TL;DR: if I join your team and you want me to use types, I'll do it! But I really feel there are ways around it but those ways may not be for everyone (and sometimes perhaps impractical).

hmmm, I dunno, this was longer than I meant it to be, haha.

Types help avoid logical bugs at every scale, though of course bigger codebases will benefit more because the likelihood of having bugs also increases. Well-typed programs don't go wrong.

> I also know three incredibly good programmers with 20-50 years experience each who all wrote in typed languages for years and then couldn't be happier not to have types when they moved to Ruby.

Typed languages from 20 to 50 years ago were very inconvenient to use and had poor compiler diagnostics that made type checking a lot less intuitive, so this isn't surprising. Modern typed languages though are very different and should not be conflated with legacy or historical ones.

Which modern language does typing really well? I would love to try a language in which it isn't frustrating to work with types.

I use types at work in Typescript and Swift but honestly I'm not very convinced it's worth the hassle in most projects. I feel that if the build tool already can tell me what type I should be using, why do I need to pedantically add them everywhere?

I don't have a lot of experience with it and you would have to make the jump over to functional programming but I really like how Ocaml does types. It's all completely inferred by the compiler. This means you have to write very explicit code when it comes to casting--you can't even add an integer and a float without casting--but I don't think this is a bad thing. You can also explicitly type things if you want, and in that case it appears on its own line as opposed to mixed in with the function args. I vastly prefer this. I can't remember exactly what it looks like in Ocaml but in Elixir it looks like:

  @spec full_name(String.t, String.t) :: String.t 
  def full_name(first_name, last_name) do
    "#{first_name} #{last_name}"
  end

As someone who historically hasn't done any typing, I still find this a little noisy, but it lets me read the function as normal and can look at the spec only if there is any confusion.

Your experience mirrors mine. I have become a dialyzer evangelist though.

What won you over?

The thing I left out was that it's only been four month of being forced to write typespecs (I actually secretly resent it when I am forced to add them to private functions) so maybe I'll come around?

Using compile time checked typed languages is the kind of continuous saving/benefit that you really feel when it's not there. For me:

- type signatures offer succinct descriptions of what a function does - I write less unit tests with proper usage of types (if you need a natural number, take a natural number type, not an integer) - building your domain and giving names to structures that are in the application (passing around MailerOptions as opposed to an 'object that contains ...') - concrete interfaces for components/services/modules in my codebase

> it's much easier to enforce coding standards, especially if you follow XP and pair all the time.

IMO where it's possible to add process that makes the bad thing an error, I do that instead of requiring/trying to enforce discipline.

> or example, in large dynamic codebases I've worked on, calling something `object` when it really means `object_id` would never fly. Variables and functions always have to be full words describing exactly what they do. Functions are only ever allowed to return one type. And of course everything is thoroughly tested.

Agree on all fo this, but regarding tests, using types does prevent me from having to worry too much.

There was a point in time where writing lots of unit tests that tested non-user inputs (is the incoming thing a number? is it less than zero somehow) was seen as clever (and it still is a good idea where appropriate). These classes of bugs just don't exist in a properly typed codebase. If you need an Integer that can't be less than zero, you want a Natural (haskell parlance).

Excessive unit tests in untyped codebases are the result of not properly specified types. If you have a function that takes a certain type, there is no reason to check if you got a string (or not that type). If you pick a language with a top of the line type system, you don't even have to check for nil.

Realizing that nothing is actually safe in languages with nullable types was a big jarring point for me way back when. I think it was when Java introduced Optional<T> that I realized it should actually be everywhere, and all the Haskell I'd been doing on the side just made way more sense.

> I'm writing this just to give the perspective of a dynamic weenie and maybe looking to be convinced a little more? I also know three incredibly good programmers with 20-50 years experience each who all wrote in typed languages for years and then couldn't be happier not to have types when they moved to Ruby. So ya, I dunno what I'm expecting here, but mostly offering my perspective.

So I say the "convincing" part a bit lightly -- I know that people must come to their own conclusions, I can only suggest the idea. People in both typed and untyped languages can be incredibly productive (my friend is much like you, so productive and disciplined that types don't seem to add much), and I can admit that adding types requires more up front thought (good) and more ceremony (~bad, especially if you don't have type inference).

Maybe the big problem is that the really good implementation of types is in languages that can be hard to approach (Haskell, OCaml, other ML langauges). The second best IMO is Rust but that has the whole separate ramp of ownership/borrowing which is hard for different reasons. Go has some good concepts (protocols) but a bunch of other warts.

I find that writing software with a good type system gives me confidence that the code is correct. It's almost axiomatic because you're building the structures that are being checked/used by the code, but nevertheless I have that much more confidence in a Typescript codebase or a Haskell codebase than an equivalent untyped codebase.

Basically I think like this:

- If I want correct, I write Haskell

- If I want quick, I write Typescript

- If I want performance, correctness and efficiency, I write Rust

Also, even if you don't believe me at all, there is a trend -- python adding typing, sorbet and other systems for ruby, typescript gaining popularity, etc. The crowd sometimes has some wisdom.

Remember, this are devs that worked on codebases that have millions lines of Ruby code (Stripe) and most probably have to handle loads of state in the application layer, so their context/anecdata might be different for your friends. I prefer dynamically typed languages for most stuff but at the scale of Stripe I would also like to have a type checker.

> vs having CI fail 20 mins after pushing up a PR because you forgot to run the typechecker script ahead of time

Have you considered using pre-commit?

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