Stop writing CLI validation. Parse it right the first time

Stop writing CLI validation. Parse it right the first time(hackers.pub)

204 points by dahlia 253 days ago | 162 comments

jmull 253 days ago |

> Think about it. When you get JSON from an API, you don't just parse it as any and then write a bunch of if-statements. You use something like Zod to parse it directly into the shape you want. Invalid data? The parser rejects it. Done.

Isn’t writing code and using zod the same thing? The difference being who wrote the code.

Of course, you hope zod is robust, tested, supported, extensible, and has docs so you can understand how to express your domain in terms it can help you with. And you hope you don’t have to spend too much time migrating as zod’s api changes.

MrJohz 253 days ago | |

I think the key part, although the author doesn't quite make it explicit, is that (a) the parsing happens all up front, rather than weaving validation and logic together, and (b) the parsing creates a new structure that encodes the invariants of the application, so that the rest of the application no longer needs to check anything.

Whether you do that with Zod or manually or whatever isn't important, the important thing is having a preprocessing step that transforms the data and doesn't just validate it.

1718627440 252 days ago | | |

But when you parse all arguments first before throwing error messages, you can create much better error messages, since they can be more holistic. To do that you need to represent the invalid configuration as a type.

makeitdouble 253 days ago | | |

The base assumption is parsing upfront cost less than validating along. I thinks it's a common case, but not common enough to apply it as a generic principle.

For instance if validating parameter values requires multiple trips to a DB or other external system, weaving the calls in the logic can spare duplicating these round trips. Light "surface" validation can still be applied, but that's not what we're talking about here I think.

bigstrat2003 253 days ago | |

Yeah, the "parse, don't validate" advice seems vacuous to me because of this. Someone is doing that validation. I think the advice would perhaps be phrased better as "try to not reimplement popular libraries when you could just use them".

lock1 253 days ago | | |

When I first saw "Parse, don't validate" title, it struck me as a catchy but perhaps unnecessarily clever catchphrase. It's catchy, yes, but it felt too ambiguous to be meaningful for anyone outside of the target audience (Haskellers in this case).

That said, I fully agree with the article content itself. It basically just boils down to:

When you create a program, eventually you'll need to process & check whether input data is valid or not. In C-like language, you have 2 options

  void validate(struct Data d);

  struct ValidatedData;
  ValidatedData validate(struct Data d);

"Parse, don't validate" is just trying to say don't do `void validate(struct Data d)` (procedure with `void`), but do `ValidatedData validate(struct Data d)` (function returning `ValidatedData`) instead.

It doesn't mean you need to explicitly create or name everything as a "parser". It also doesn't mean "don't validate" either; in `ValidatedData validate(struct Data d)` you'll eventually have "validation" logic similar to the procedure `void` counterpart.

Specifically, the article tries to teach folks to utilize the type system to their advantage. Rather than praying to never forget invoking `validate(d)` on every single call site, make the type signature only accept `ValidatedData` type so the compiler will complain loudly if future maintainers try to shove `Data` type to it. This strategy offloads the mental burden of remembering things from the dev to the compiler.

I'm not exactly sure why the "Parse, don't validate" catchphrase keeps getting reused in other language communities. It's not clear to non-FP community what the distinction between "parser" and "validate", let alone "parser combinator". Yet somehow other articles keep reusing this same catchphrase.

dwattttt 253 days ago | | |

Sibling says this with code, but to distil the advice: reflect the result of your validation in the type system.

Then instead of validating a loose type & still using the loose type, you're parsing it from a loose type into a strict type.

The key point is you never need to look at a loose type and think "I don't need to check this is valid, because it was checked before"; the type system tracks that for you.

antonvs 251 days ago | | |

> Someone is doing that validation.

The difference is (a) where and how validation happens, and (b) the type of the final result.

A parser is a function producing structured values - values of some type, usually different from the input type. In contrast, a validator is a predicate that only checks constraints on existing values.

For example, a parser can parse an email address into a variable of type EmailAddress. If the parser succeeds at doing that, assuming you're using a language with a decent type system, you now have a variable which is statically guaranteed to be an email address - not a string which you have to trust has passed validation at some point in the past.

This is part of the "Make illegal states unrepresentable" approach which allows for static debugging - debugging your code at compile time. It's a very powerful way to produce reliable systems with robust, statically proven guarantees.

But as Alexis King (who coined the phrase "Parse, don't validate") wrote, "Unless you already know what type-driven design is, my catchy slogan probably doesn’t mean all that much to you."

remexre 253 days ago | | |

The difference between parse and validate is

    function parse(x: Foo): Bar { ... }

    const y = parse(x);

and

    function validate(x: Foo): void { ... }

    validate(x);
    const y = x as Bar;

Zod has a parser API, not a validator API.

geon 252 days ago | | |

This might be a clearer phrasing: "Parse and validate ONCE AND FOR ALL, instead of sprinkling validation everywhere you need to access the data."

But I suppose it isn't as catchy.

yakshaving_jgt 253 days ago | | |

Parsing includes validation.

The point is you don’t check that your string only contains valid characters and then continue passing that string through your system. You parse your string into a narrower type, and none of the rest of your system needs to be programmed defensively.

To describe this advice as “vacuous” says more about you than it does about the author.

akoboldfrying 253 days ago | |

Yes, both are writing code. But nearly all the time, the constraints you want to express can be expressed with zod, and in that case using zod means you write less code, and the code you do write is more correct.

> Of course, you hope zod is robust, tested, supported, extensible, and has docs so you can understand how to express your domain in terms it can help you with. And you hope you don’t have to spend too much time migrating as zod’s api changes.

Yes, judgement is required to make depending on zod (or any library) worthwhile. This is not different in principle from trusting those same things hold for TypeScript, or Node, or V8, or the C++ compiler V8 was compiled with, or the x86_64 chip it's running on, or the laws of physics.

jmull 253 days ago | | |

Sure... the laws of physics last broke backwards compatibility at the Big Bang, Zod last broke backwards compatibility a few months ago.

bschwindHN 253 days ago |

Rust with Clap solved this forever ago.

Also - don't write CLI programs in languages that don't compile to native binaries. I don't want to have to drag around your runtime just to execute a command line tool.

12_throw_away 253 days ago |

I like this advice, and yeah, I always try to make illegal states unrepresentable, possibly even to a fault.

The problem I run into here is - how do you create good error messages when you do this? If the user has passed you input with multiple problems, how do you build a list of everything that's wrong with it if the parser crashes out halfway through?

nine_k 253 days ago |

This is a recurring idea: "Parse, don't validate". Previously:

https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-va... (2019, using Haskell)

https://www.lelanthran.com/chap13/content.html (April 2025, using C)

jetrink 253 days ago | |

The author credits Alexis King at the beginning and links to that post.

amterp 252 days ago |

Very much agree with the article, this is one of the reasons why I wrote Rad [0], which people here might find interesting. The idea is you write CLI scripts with a declarative approach to script arguments, including all the constraints on them, including relational ones. So you don't write your own CLI validation - you declare the shape that args should take, let Rad check user input for you, and you can focus your script on the interesting stuff. For example

  args:
      username str           # Required string
      password str?          # Optional string
      token str?             # Optional auth token
      age int                # Required integer
      status str             # Required string
  
      username requires password     // If username is provided, password must also be provided
      token excludes password        // Token and password cannot be used together
      age range [18, 99]             // Inclusive range from 18 to 99
      status enum ["active", "inactive", "pending"]

Rad will handle all the validation for you, you can just write the rest of your script assuming the constraints you declared are met.

[0]: https://github.com/amterp/rad

SloopJon 253 days ago |

I don't see anything in the post or the linked tutorial that gives a flavor of the user experience when you supply an invalid option. I tried running the example, but I've forgotten too much about Node and TypeScript to make it work. (It can't resolve the @optique references.) What happens when you pass --foo, --target bar, or --port 3.14?

macintux 253 days ago | |

I had a similar question: to me, the output format “or” statement looks like it might deterministically pick one winner instead of alerting the user that they erred. A good parser is terrific, but it needs to give useful feedback.

Dragging-Syrup 253 days ago | | |

Absolutely; I think calling the function xor would be more appropriate.

andrewguy9 253 days ago |

Docopt!

http://docopt.org/

Make use of the usage string be the specification!

A criminally underused library.

fragmede 253 days ago | |

My favorite. A bit too much magic for some, but it seems well specified to me.

tomjakubowski 253 days ago | |

A great example of "declaration follows use" outside of C syntax.

esafak 253 days ago |

The "problem" is that some languages don't have rich enough type systems to encode all the constraints that people want to support with CLI options. And many programmers aren't that great at wielding the type systems at their disposal.

globular-toast 253 days ago |

Not all of this validation belongs in the same layer. A lot of the problems people seem to have is due to people thinking it all has to be done in the I/O layer.

A CLI and an API should indeed occupy the same layer of a program architecture, namely they are entry points that live on the periphery. But really all you should be doing there is lifting the low byte stream you are getting from users to something higher level you can use to call your internals.

So "CLI validation" should be limited to just "I need an int here, one of these strings here, optionally" etc. Stuff like "is this port out of range" or "if you give me this I need this too" should be handled by your internals by e.g. throwing an exception. Your CLI can then display that as an error message in a nice way.

yakshaving_jgt 253 days ago |

I've noticed that many programmers believe that parsing is some niche thing that the average programmer likely won't need to contend with, and that it's only applicable in a few specific low-level cases, in which you'll need to reach for a parser combinator library, etc.

But this is wrong. Programmers should be writing parsers all the time!

WJW 253 days ago | |

Last week my primary task was writing a github action that needed to log in to Heroku and push the current code on main and development branches to the production and staging environments respectively. The week before that, I wrote some code to make sure the type the object was included in the filters passed to an API call.

Don't get me wrong, I actually love writing parsers. It's just not required all that often in my day-to-day work. 99% of the time when I need to write a parser myself it's for and Advent of Code problem, usually I just import whatever JSON or YAML parser is provided for the platform and go from there.

yakshaving_jgt 253 days ago | | |

Do you not write validation? Or handle user input? Or handle server responses? Surely there’s some data processing somewhere.

eska 253 days ago | |

I think most security issues are just due to people not parsing input at all/properly. Then security consultants give each one a new name as if it was something new. :-)

dkubb 253 days ago | |

The three most common things I think about when coding are DAGs, State Machines and parsing. The latter two come up all the time in regexps which I probably write at least once a day, and I’m always thinking about state transitions and dependencies.

nine_k 253 days ago | |

I'd say that engineers should use the highest-level tools that are adequate for the task.

Sometimes it's going down to machine code, or rolling your own hash table, or writing your own recursive-descent parser from first principles. But most of the time you don't have to reach that low, and things like parsing are but a minor detail in the grand scheme. The engineer should not spend time on building them, but should be able to competently choose a ready-made part.

I mean, creating your own bolts and nuts may be fun, but mot of the time, if you want to build something, you just pick a few from an appropriate box, and this is exactly right.

yakshaving_jgt 253 days ago | | |

I don’t understand. Every mainstream language has libraries for parsing into general types, but none of them will have libraries for parsing values specific to your application.

TFA links to Alexis King’s Parse, Don’t Validate article, which explains this well. Did you not read it?

SoftTalker 253 days ago |

I like just writing functions for each valid combination of flags and parameters. Anything that isn’t handled is default rejected. Languages like Erlang with pattern matching and guards make this a breeze.

bsoles 253 days ago |

>> // This is a parser

>> const port = option("--port", integer());

I don't understand. Why is this a parser? Isn't it just way of enforcing a type in a language that doesn't have types?

I was expecting something like a state machine that takes the command line text and parses it to validate the syntax and values.

hansvm 253 days ago | |

The heavy lifting happens in the definitions of `option` and `integer`. Those will take in whatever arguments they take in and output some sort of `Stream -> Result<Tuple<T, Stream>>` function.

That might sound messy but to the author's point about parser combinators not being complicated, they really don't take much time to get used to, and they're quite simple if you wanted to build such a library yourself. There's not much code (and certainly no magic) going on under the hood.

The advantage of that parsing approach:

It's reasonably declarative. This seems like the author's core point. Parser-combinator code largely looks like just writing out the object you want as a parse result, using your favorite combinator library as the building blocks, and everything automagically works, with amazing type-checking if your language has such features.

The disadvantages:

1. Like any parsing approach, you have to actually consider all the nuances of what you really want parsed (e.g., conditional rules around whitespace handling). It looks a little to me (just from the blog post, not having examined the inner workings yet) like this project side-stepped that by working with the `Stream` type as just the `argv` list, allowing you to be able to say things like "parse the next blob as a string" without also having to encode whitespace and blob boundaries.

2. It's definitely slower (and more memory-intensive) than a hand-rolled parser, and usually also worse in that regard than other sorts of "auto-generated" parsing code.

For CLI arguments, especially if they picked argv as their base stream type, those disadvantages mostly don't exist. I could see it performing poorly for argv parsing for something like `cp` though (maybe not -- maybe something like `git cp`, which has more potential parse failures from delimiters like `--`?), which has both options and potentially ginormous lists of files; if you're not very careful in your argument specification then you might have exponential backtracking issues, and where that would be blatantly obvious in a hand-rolled parser it'll probably get swept under the rug with parser combinators.

einpoklum 253 days ago |

Exactly the opposite of this. We should parse the command-line using _no_ strict types. Not even integers. Nothing beyond parsing its structure, e.g. which option names get which (string) values, and which flags are enabled. This can be done without knowing _anything_ about the application domain, and provide a generic options structure which is no longer a sequence of characters.

This approach IMNSHO is much cleaner than the intrication of cmdline parser libraries with application logic and application-domain-related types.

Then one can specify validation logic declaratively, and apply it generically.

This has the added benefit - for compiled rather than interpreted library - of not having to recompile the CLI parsing library for each different app and each different definition of options.

MrJohz 253 days ago | |

Can you give some examples of this working well? It certainly goes against all of my experience working with CLIs and with parsing inputs in general (e.g. web APIs etc). In general, I've found that the quicker I can convert strings into rich types, the easier that code is to work with and the less likely I am to have troubles with invalid data.

einpoklum 252 days ago | | |

Think of it this way: Your code for quickly converting things into rich types - just run it on a map of argument-to-string value map rather than on a sequence of characters. It's still "quick": This is just like we current get an array-of-strings instead of a single-string command-line; it's initial domain-agnostic parsing, which can't even fail.

bakkoting 250 days ago | |

This is the approach taken by node's built-in argument parser util.parseArgs.

m463 253 days ago |

This kind of stuff is what makes me appreciate python's argparse.

It's a genuine pleasure to use, and I use it often.

If you dig a little deeper into it, it does all the type and value validation, file validation, it does required and mutually exclusive args, it does subargs. And it lets you do special cases of just about anything.

And of course it does the "normal" stuff like short + long args, boolean args, args that are lists, default values, and help strings.

MrJohz 253 days ago | |

Actually, I think argparse falls into the same trap that the author is talking about. You can define lots of invariants in the parser, and say that these two arguments can't be passed together, or that this argument, if specified, requires these arguments to also be specified, etc. But the end result is a namespace with a bunch of key-value pairs on it, and argparse doesn't play well with typing systems like mypy or pyright. So the rest of the tool has to assume that the invariants were correctly specified up-front.

The result is that you often still this kind of defensive programming, where argparse ensures that an invariant holds, but other functions still check the same invariant later on because they might have been called a different way or just because the developer isn't sure whether everything was checked where they are in the program.

What I think the author is looking for is a combination of argparse and Pydantic, such that when you define a parser using argparse, it automatically creates the relevant Pydantic classes that define the type of the parsed arguments.

bvrmn 253 days ago | | |

In general case generating CLI options from app models leads to horrible CLI UX. Opposite is also true. Working with "nice" CLI options as direct app models is horrendous.

You need a boundary to convert nice opts into nice types. Like pydantic models could take argparse namespace and convert it to something manageable.

sgarland 253 days ago | | |

Precisely my thought. I love argparse, but you can really back yourself into a corner if you aren’t careful.

js2 253 days ago | | |

> What I think the author is looking for is a combination of argparse and Pydantic

Not quite that, but https://typer.tiangolo.com/ is fully type driven.

hahn-kev 253 days ago | | |

It's almost like you want compile time type safety

geon 252 days ago |

I just recently implemented my own parser combinator lib in typescript too. It was surprisingly simple in the end.

This function parses a number in 6502 asm. So `255` in dec or `$ff` in hex: https://github.com/geon/dumbasm/blob/main/src/parsers/parseN...

I looked at several typescript libraries but they all felt off. Writing my own at least ensured I know how it works.

AndrewDucker 253 days ago |

This is one of the things that makes me glad that PowerShell does all of this intrinsically. I define the parameters, it makes sure that the arguments make sense and match them (and their validation).

AnimalMuppet 252 days ago |

Well, they're dictating that if you want them to use it, do it this way. Some people want others to use the programs they write; for such people, the GP actually has been given the right to have some valid say in the matter.

Why CLIs in particular? Because they usually are smaller tools. For a big, important tool, you might be willing to jump through more hoops (installing the right runtime), but for a smaller, less important tool, it's just not worth it.

dvdkon 253 days ago |

I, for one, do think the world needs more CLI argument parsers :)

This project looks neat, I've never thought to use parser combinators for something other than left-to-right string/token stream parsing.

And I like how it uses Typescript's metaprogramming to generate types from the parser code. I think that would be much harder (or impossible) in other languages, making the idiomatic design of a similar similar library very different.

kiliancs 253 days ago |

Great project. Clear goal, well executed, very nice API (safe, terse, clear).

I use Effect CLI https://github.com/Effect-TS/effect/tree/main/packages/cli for the same reasons. It has the advantage of fitting within the ecosystem. For example, I can reuse existing schemas.

lihaoyi 253 days ago |

That's basically what my MainArgs Scala library does: take either a method definition or class structure and use it's structure to parse your command line arguments. You get the final fields you want immediately without needing to imperatively walk to args array (and probably getting it wrong!)

https://github.com/com-lihaoyi/mainargs

foundart 253 days ago |

The author of the article also wrote a CLI parser library for Typescript, called Optique. I really appreciate them including a "When Optique makes sense" section in the docs. It would be great if more projects did that.

https://optique.dev/why#when-optique-makes-sense

dcre 253 days ago |

Some other libraries I’ve been enjoying building CLIs with in TS that do more or less the same thing, though perhaps with slightly worse composability than Optique:

https://cliffy.io/

https://github.com/tj/commander.js

jappgar 253 days ago |

I really think parse don't validate gives people a false sense of security (particularly false in dynamic languages like javascript and python).

"Well, I already know this is a valid uuid, so I don't really need to worry about sql injection at this point."

Sure, this is a dumb thing to do in any case, but I've seen this exact thing happen.

Typesafety isn't safety.

yakshaving_jgt 253 days ago | |

Type safety is absolutely some degree of safety. And I don’t know why anyone would think parsing a value into a type that has fewer inhabitants would absolve them of having to prevent SQL injection — these are orthogonal things.

The quote here — which I suspect is a straw man — is such a weird non sequitur. What would logically follow from “I already know this is a valid UUID” is “so I don’t need to worry about this not being a UUID at this point”.

jappgar 252 days ago | | |

In python or typescript, the most popular languages in the world, it offers no runtime safety.

Even in languages like Haskell, "safety" is an illusion. You might create a NumberGreaterThanFive type with smart constructors but that doesn't stop another dev from exporting and abusing the plain constructor somewhere else.

For the most part it's fine to assume the names of types are accurate, but for safety critical operations it absolutely makes sense to revalidate inputs.

baroninthetrees 252 days ago |

I too got tired of dealing with cli arg parsing and am experimenting with passing a natural language description of the program and its args to a tiny LLM to sort out, offer suggestions (did you mean?), types conversions, etc. So far, it’s working great and given enough detail is deterministic.

jiggawatts 253 days ago |

This is one of the many reasons I like PowerShell: it parses strongly typed parameters for you and outputs human readable error messages for every kind of validation failure.

thealistra 253 days ago |

Isn’t this like argparse from Python for typescript?

whilenot-dev 253 days ago | |

What OP calls an "combinatorial parser" I'd call object schema validation and that's more similar to pydantic[0] than argparse in python land.

[0]: https://docs.pydantic.dev/latest/

nhumrich 253 days ago | | |

So, typer than

adamddev1 253 days ago |

Yay for parser combinators in the JS/TS wild!

brabel 253 days ago | |

Exactly, the author's library is just a parser combinator [1] that specializes in providing constructs mirrorring CLI options.

[1] https://en.wikipedia.org/wiki/Parser_combinator

nickdothutton 253 days ago |

It’s been about 30 years but I seem to remember the compiler taking care of this for me (in Ada) with types.

ThinkBeat 253 days ago |

And that is why there are plenty of parser generators so you dont have to write the parser yourself every time.

sudahtigabulan 253 days ago |

Is there no getopt implementation for Typescript? The input this library tries to handle better looks to me like bad design.

"options that depend on options" should not be a thing. Every option should be optional. Even if you have working code that can handle some complex situation, this doesn't make the situation any less unintuitive for the users.

If you need more complex relationships, consider using arguments as well. Top level, or under an option. Yes, they are not named, but since they are mandatory anyway, you are likely to remember their meaning (spaced repetition and all that). They can still be optional (if they come last). Sometimes an argument may need to have multiple parts, like user@host:port You can still parse it instead of validating, if you want.

> mutually exclusive --json, --xml, --yaml.

Use something like -t TYPE instead, where TYPE can be one of json, xml, or yaml. (Make illegal states unrepresentable.)

> debug: optional(option("--debug")),

Again, I believe it's called "option" because it's meant to be optional already.

  optional(optional(option("--common-sense")))

EOR

dwattttt 253 days ago | |

> options that depend on options

What would you do for "top level option, which can be modified in two other ways"?

  (--option | --option-with-flag1 | --option-with-flag2 | --option-with-flag1-and-flag2)

would solve invalid representation, but is unwieldy.

Something that results in the usage string

  [--option [--flag1 --flag2]]

doesn't seem so bad at that point.

sudahtigabulan 253 days ago | | |

I think I've seen it done like that

  --option flag1,flag2

(Maybe with another separator, as long as it doesn't need to be escaped.)

Another possibility is to make the main option an argument, like the subcommands in git, systemctl, and others:

  command option --flag1 --flag2

This depends on the specifics, though.

Spivak 253 days ago | |

I think ultimately you're trying to tell a river that it's going the wrong way. Programs have had required options for decades at this point. I think they can make sense as alternatives to heterogeneously typed positional arguments. By making the user name them explicitly you remove ambiguity and let the user specify them in whatever order they please.

In Python this was a motivating factor for letting functions demand their arguments be passed as named keywords. Something like send("foo", "bar") is easier to understand and call correctly when you have to say send(channel="foo", message="bar")

slifin 253 days ago |

So use Clojure Spec or better yet Malli to parse your input data at the edges of your program

Makes sense, I think a lot of developers would want to complect this problem with their runtime type system of choice without considering the set of downsides for the users

panzi 253 days ago |

No mention of yargs?

parhamn 253 days ago |

> Try to access it and TypeScript yells at you. No runtime validation needed.

I was recently thinking about type safety and validation strategies are particularly thorny in languages where the typings are just annotations. E.g. the Typescript/Zod or Python/Pydantic universes. Especially in IO cases where the data doesn't originate in the same type system.

In a language like Go (just an example, not endorsing) if you parse something into say a struct you know worst case you're getting that struct with all the fields set to zero, and you just have to handle the zero values. In typescript-likes you can get a totally different structure and run into all sorts of errors.

All that is to say, the runtime validation is always somewhere (perhaps in the library, as they often are?), and the feature here isn't no runtime validation but typed cli arguments. Which is cool and great.

metaltyphoon 253 days ago | |

> worst case you're getting that struct with all the fields set to zero, and you just have to handle the zero values

In the field I work, zero values are valid and doing it in Go would be a nightmare

mjevans 253 days ago | | |

Database NULL is a valid pattern that any parser SHOULD support and I do consider that a design bug in every parser Go has. Offhand most of them effectively 'update' an object, but make it difficult or impossible to tell if something was __set__ with a value, or merely inherited a default.

parhamn 253 days ago | | |

Agreed, the pointer or "<field>_empty: bool" patterns are annoying. Point still stands though, you always get the structure you ask for.

bvrmn 253 days ago |

A valid type for server and port should be a single value. Stop parse it separately please.

":3000" -> use port 3000 with a default host.

"some-host" -> use host with a default port.

"some-host:3000" -> you guess it.

It also allows to extend it to other sources/destinations like unix domain sockets and other stuff without cluttering your CLI options.

Also please consider to use DSN or URI to define database configurations. Host, port, dbname, credentials as separate options or environment variables are quite painful to use.

HL33tibCe7 253 days ago |

Stopped reading after realising this is written by ChatGPT

akoboldfrying 253 days ago | |

I found the content novel and helpful (applying a known but underappreciated technique (Parse, Don't Validate) to a common problem where I hadn't thought to use it before) and the tone very enjoyable. In fact, it's so idiomatically written that I can't even believe it's just a machine translation of something written in another language.

In short, a great article.

cazum 253 days ago | |

What makes you think that and not that it's just an average auto-translate job from the author's native language (Korean)?

urxvtcd 253 days ago | | |

I’ll go one step further: what makes you think it’s an average auto-translate job? I didn’t notice anything weird, felt like your average, slightly ranty HN post. I’m not a native speaker though.

bfung 253 days ago | |

Looked human-ish to me, what signs did you see?

bobbiechen 253 days ago | | |

I thought the style was like ChatGPT in a "clever, casual, snarky" prompt flavor as well. I see it a lot on LinkedIn especially in sentence structures like these:

"Invalid data? The parser rejects it. Done."

"That validation logic that used to be 30% of my CLI code? Gone."

"Mutually exclusive groups? Sure. Context-dependent options? Why not."

For me this really piled on at the end of the blog post. But maybe it's just personal style too.

AfterHIA 253 days ago |

You've got to be careful; if you validate the CLI too much you might get URA in your validator. #chugalug #house

$ ldd /usr/bin/rg linux-vdso.so.1 (0x00007fff45dd7000) libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x000070764e7b1000) libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x000070764e6ca000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000070764de00000) /lib64/ld-linux-x86-64.so.2 (0x000070764e7e6000)

$ wget 'https://github.com/BurntSushi/ripgrep/releases/download/14.1.1/ripgrep-14.1.1-x86_64-unknown-linux-musl.tar.gz' $ tar -xvf 'ripgrep-14.1.1-x86_64-unknown-linux-musl.tar.gz' $ ldd ripgrep-14.1.1-x86_64-unknown-linux-musl/rg ldd (0x7f1dcb927000) $ file ripgrep-14.1.1-x86_64-unknown-linux-musl/rg ripgrep-14.1.1-x86_64-unknown-linux-musl/rg: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), static-pie linked, stripped

$ pkg install git rust $ git clone https://github.com/BurntSushi/ripgrep.git $ cd ripgrep $ RUSTFLAGS='-C target-feature=+crt-static' cargo build --release $ ldd target/release/rg ldd: target/release/rg: not a dynamic ELF executable $ file target/release/rg target/release/rg: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), statically linked, for FreeBSD 14.3, FreeBSD-style, with debug_info, not stripped