HackerReposA FIELD GUIDE TO OPEN SOURCE
ProSponsor the shelf♧ 0
← Back to top all-time
clap-rs
clap
Rust2017–2026
clap-rs / clap

clap

A full featured, fast Command Line Argument Parser for Rust

Command LineLanguages & Compilers
Explore on GitHubRead Hacker News discussions
18Distinct people
21Mentions
0Explicit recommenders
16.9KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

A full featured, fast Command Line Argument Parser for Rust

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year21 dated mentions

Observed mentions: 2017-03-22 21:45:56 UTC to 2026-01-14 14:05:20 UTC.

012342017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20172018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments20212022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 4 mentions; 0 submissions, 4 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2026-01-01 00:00:00 UTC to 2027-01-01 00:00:00 UTC (exclusive): 1 mentions; 1 submissions, 0 comments. Incomplete calendar period.2026*

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC101
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC202
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC211
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC303
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC303
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC404
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC202
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC202
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC101
2026 (partial)2026-01-01 00:00:00 UTC2027-01-01 00:00:00 UTC110

What Hacker News says

21 sources
KingOfCoders·Jan 14, 2026Submission

Show HN: Convert Go to Rust

I announce rinku to the world! With people looking less and less at code, why not choose a language with better runtime characteristics instead of the one you wanted to write code in before? As a Go coder I have migrated several of my small tools to Rust, as Rust is faster, uses less memory and has no GC latency (wish Go had arenas). The main obstacle was mapping third party dependencies like open source libraries. As a solution I have created 'rinku'. You give it a Go dependency and it gives you a Rust dependency. > $ rinku lookup https://github.com/spf13/cobra > https://github.com/clap-rs/clap Prompt now becomes (real prompt is more complicated) > Translate the project from Go to Rust. For dependencies migration use rinku. The library of mappings is not yet extensive, but migration is now much easier. https://github.com/marvai-dev/rin
Read the rest
ku
1 points · Open discussion
epage·Aug 21, 2024
> To the extent there is an exception, testing-only code may be. Testing-only code has very different constraints than production code anyhow. Even then, though, I still find that refactoring problem arises, and test code needs to be refactorable too. For me, I avoid defining anything within a function except when that thing being defined is what is being tested in a test, e.g. https://github.com/clap-rs/clap/blob/87647d268c8c27e3298b2c0...
In The weird of function-local types in Rust
nfachan·Jul 10, 2024
Our desire is to provide a general test-running and job-running framework, not to built the world's next test runner. We think nextest is great, and we were inspired by some of the things they did. We've designed Maelstrom to be usable as a library. So you can build your own test runner or job runner. We've been in contact with Rain, the primary developer of nextest, regarding how we can make it so that nextest can use Maelstrom. We'd love nothing more than to have nextest be Maelstrom-ized (Maelstrom-ified?). We definitely have a little bit of work to do, but we plan to make big steps with the API for the next release. Currently, the client library doesn't give per-test updates until the test finishes. This means that you don't know how long a test is taking to run until it's completed (though we do provide a timeout feature). This is fi
Read the rest
ne for our currently limited UI, but is probably insufficient for nextest. Maelstrom in standalone mode running on a single machine is usually a bit slower than nextest. Maelstrom and nextest are similar in that they both run each test in their own processes, and they both do a good job of running enough test processes in parallel to keep the machine busy. Maelstrom has to do a little bit more work each time it starts a new process to set up the namespaces, so it's always going to be a bit slower than nextest, but not by much. One thing that Maelstrom does that I don't think nextest does is to use Longest Processing Time First (LPT) scheduling (https://en.wikipedia.org/wiki/Longest-processing-time-first_...). When the runtimes of tests varies a lot within a project, using LPT can result in big wins and more predictable runtimes. Maelstrom itself actually has some pretty long-running integration tests, and once we added LPT, running Maelstrom tests on Maelstrom is usually faster than running them on nextest. But again, we're not talking about huge differences in single-machine cases. I think cargo test is usually slower than both Maelstrom and nextest for the reasons described in the nextest documentation: cargo test doesn't always keep enough test threads running to keep the machine busy. However, if you have a lot of really small tests all in a single crate, then cargo test can and does outperform both Maelstrom and nextest. The clap project (https://github.com/clap-rs/clap)is a good example of this. I think Maelstrom does most of the performance things that nextest does. However, nextest obviously has a lot more features and integrations than Maelstrom.
In Show HN: Maelstrom – A Hermetic, Clustered Test Runner for Python and Rust
epage·May 19, 2022
I find rustdoc lacking for clap. rustdoc does a good job with API reference documentation and is improving in its handling of examples but derive reference and tutorial documentation are a weak point. For examples, its improving with the example scraping work (e.g. https://docs.rs/clap/latest/clap/struct.ArgMatches.html#meth...) but testing of example is still lacking. I've written trycmd to help (https://github.com/assert-rs/trycmd). For derive reference and tutorial documentation, your choices are - A very long, hard to navigate top-level documentation, see https://docs.rs/structopt/latest/structopt/ - External documentation, see https://serde.rs/ - Dummy modules to store your documentation (I've seen this used but can't remember one off the top of my head) For clap, my documentation examples are best served as programs and we've had
Read the rest
a problem with these being broken. The Rust CLI book has a decent strategy for this by pulling in code from external files (https://rust-cli.github.io/book/index.html). I was tempted to do that for clap where example code and output (all verified via trycmd) are pulled into an mdbook site but I've stopped short and just have a README that links out to everything (https://github.com/clap-rs/clap/blob/master/examples/tutoria...). Its not great.
In Rust: A Critical Retrospective
yakubin·May 19, 2022
> If you're going to do that, would you not be better saving all that time and code bloat (it's code you wrote that doesn't contribute to solving your problem) by just using a garbage collector from the outset? I suspect a garbage collector would be pretty nice. However, I can't just list the features I want and get a language (unless I make it myself, which would take a lot of time). Currently, my imaginary perfect language would actually have a garbage collector, would be pretty similar to Standard ML, but would be more focused on arrays than lists, and would have value types --- in Standard ML I can't have a value array of records (structs in Rust/C++ parlance) --- they will be behind a pointer. And if I were to stick to the standard or make sure that my code compiles with other compilers than MLTon, then I can't even have a value arra
Read the rest
y of 64-bit words, although I can have a value array of 63-bit words. This one bit may seem insignificant, but for certain algorithms it's a big complication. Powers of 2 simplify a lot of algorithms (and are "faster" to be a bit loose with the language). There are other features I'd like, but already this short list makes for a currently-non-existent language. OCaml and Haskell have similar problems to Standard ML. At the same time Rust has great support for arrays, is expression-oriented, has sum types. Value types are the default. It generally ticks a lot of boxes I care about. I can't just go and say "now give me all that but with a GC" and have it appear before me. Also, arenas I use are linked to logical portions of my programs. They are not contrivances that I had to think long and hard about. They don't waste my time really. I've spent 0 time thinking about how they should be organized. Now the part where a GC would be helpful is a bit of a more liberal use of closures, and eliminating code noise coming from lifetime annotations such as "for<'a>". But I can live with the current state of affairs, if I get all the other benefits. > If you're going to do that, would you not be better saving all that time and code bloat (it's code you wrote that doesn't contribute to solving your problem) by just using a garbage collector from the outset? If anything, Rust is an asset for large teams of devs. Even though you may sometimes argue that a handful of C/C++ devs can keep their whole project in their heads and not make mistakes (although I think that's a stretch), the moment you get a large C/C++ team, weird hard-to-debug bugs coming from memory- and thread-safety issues start to creep in. There are other high-level languages, but Rust is the one with a combination of performance competitive with C++ and large ecosystem of libraries you can use. Examples of Rust projects with a large number of contributors facilitated by the language taking the fear of intractable bugs away: - <https://github.com/BurntSushi/ripgrep> - <https://github.com/clap-rs/clap> - <https://github.com/rayon-rs/rayon> - <https://github.com/cloudflare/wrangler> - <https://github.com/sharkdp/fd>
In The Rust Borrow Checker – A Deep Dive
dbrgn·Dec 31, 2021
I like Docopt for quick scripts, used it both in Python and Rust projects. It is quite unflexible though. The Rust Docopt implementation¹ was deprecated this year, which is probably good because clap v3² is so awesome. In a project of mine (tealdeer), I noticed that docopt.rs was responsible for the huge majority of CPU instructions when running the binary: https://github.com/dbrgn/tealdeer/issues/106#issuecomment-59... I then switched³ to clap and shaved off almost a megabyte from the release binary⁴. Performance improved as well, time required for rendering a tldr page went down from ~15.9 ms to ~12.4 ms⁵. With the migration, we also managed to reduce a lot of custom validation logic and move this logic into the derive macro attributes. ¹ https://github.com/docopt/docopt.rs ² https://github.com/clap-rs/clap ³ https://github.com/dbrgn/te
Read the rest
aldeer/pull/108 ⁴ https://github.com/dbrgn/tealdeer/pull/108#issuecomment-9448... ⁵ https://github.com/dbrgn/tealdeer/pull/108#issuecomment-9448...
In Docopt
epage·Nov 2, 2021
The main arg parser for Rust (clap) was looking at using sysexits for usage but then got feedback from burntsushi (of ripgrep fame) for how rarely it is used and instead encouraged 2. In looking at it, it seems like 2 is the most consistent code and for clap v3 will be using it. - 2 is "misuse of shell built-ins" for bash [1] - Python's argparse uses 2 [2] I feel like we looked at more but can't remember which all they were [0] https://github.com/clap-rs/clap/pull/1637#issuecomment-58103... [1] https://tldp.org/LDP/abs/html/exitcodes.html [2] https://github.com/python/cpython/blob/main/Lib/argparse.py#...
In Sysexits – preferable exit codes for programs
csnover·Oct 4, 2020
I get how important UX is, and I still struggle to fathom what in structopt even generates 20x more machine code and 30x slower compilation versus a simpler argument parser which can do 95% of the job. Someone at some time thought that every line of code had to be there for some reason, but it just doesn’t seem like a reasonable default choice to me for most apps, because it’s a huge penalty just to handle some edge cases that won’t come up most of the time. ripgrep, your example of something demands a complex arguments parsing system, seems to have had problems with unnecessary changes in clap (on which structopt is based) slowing down compilation for no reason[0][1] and currently uses none of its configurable features except suggestions[2]. [0] https://github.com/BurntSushi/ripgrep/commit/c8e755f11f31b6d... [1] https://github.com/clap-r
Read the rest
s/clap/commit/739e7048a50d14023ef9e... [2] https://github.com/BurntSushi/ripgrep/blob/def993bad1a9275cd...
In Rust Starter Kit 2020

Showing the 15 most recent of 21 sources. Enable JavaScript to search and browse every indexed mention.

MAKE YOURSELF AT HOME

A few shortcuts

/
Search the collection
?
Open this guide
Esc
Close dialogs and navigation

Your saved repositories and interests stay in this browser.