haskell-hedgehog

Release with confidence, state-of-the-art property testing for Haskell.

Testing & Quality

Explore on GitHub Read Hacker News discussions

2Distinct people

2Mentions

0Explicit recommenders

701GitHub stars

REPOSITORY AT A GLANCE

What to know before exploring

What it is

Release with confidence, state-of-the-art property testing for Haskell.

GitHub

Where it is used

No documented product use has been verified yet.

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

No other repository is repeatedly linked in the same discussions.

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 hour2 dated mentions

Observed mentions: 2024-07-04 17:21:55 UTC to 2024-07-04 17:40:31 UTC.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC. One observed period does not establish a trend.

View mention counts and date ranges

UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
Period	Start (UTC)	End (exclusive, UTC)	Mentions	Submissions	Comments
Jul 4, 17:00	2024-07-04 17:00:00 UTC	2024-07-04 18:00:00 UTC	2	0	2

What Hacker News says

2 sources

AlexErrant·Jul 4, 2024

> - rose tree "integrated shrinking" (eg. Hedgehog) follows the constraints of the generators, but has issues with monadic bind. We're at the limits of my amateur knowledge, but I believe this is a fundamental limitation of monadic bind/generators. Instead, you should prefer applicative generators for optimal shrinking. https://github.com/hedgehogqa/haskell-hedgehog/issues/473#is... In other words, applicative generators do not use "results of generators to dispatch to another generator", but instead shrinking is optimal due to the "parallel" nature of applicatives (I'm using "parallel" in the monadic sense, and not the sense of article's "threading" sense). Since applicatives are "parallel", they can shrink the generators independently. (Whereas monadic generators are in "series" and therefore shrinking one necessarily changes the behavi

Read the rest

or of the subsequent generator, as you noted.) Please feel free to link your talk if it's public!

In The sad state of property-based testing libraries

sshine·Jul 4, 2024

Amazing survey. Big fan of property testing. A particularly big fan of Hedgehog. I tried writing a Hedgehog-inspired library in Rust and realized how complex the underlying domain is. For example, the RNG is "splittable" [1][2] which means you can take a deterministic seed and split it in two, e.g. for parallel generators to work independently but still deterministically. The effort that has gone into this feature level is a little numbing. I have an awe similar to that of the "fast inverse square root" hack when I see code like this: -- | A predefined gamma value's needed for initializing the "root" instances of -- 'Seed'. That is, instances not produced by splitting an already existing -- instance. -- -- We choose: the odd integer closest to @2^64/φ@, where @φ = (1 + √5)/2@ is -- the golden ratio. -- goldenGamma

Read the rest

:: Word64 goldenGamma = 0x9e3779b97f4a7c15 when realizing that those numbers don't come easily. [3] [1]: https://hackage.haskell.org/package/hedgehog-1.4/docs/src/He... [2]: https://gee.cs.oswego.edu/dl/papers/oopsla14.pdf [3]: https://github.com/hedgehogqa/haskell-hedgehog/issues/191 Wonder why most property-testing libaries don't have features like this? The libraries require training to use. And they're not that easy to write. > the current state-of-the-art when it comes to property-based testing is stateful testing via a state machine model and reusing the same sequential state machine model combined with linearisability to achieve parallel testing Okay, okay. I admit I've never performed property-based stateful testing, nor in parallel. So that may be the coolest feature out there, because it addresses one of the hardest problems in testing. But I think that yet other things have happened with modern property-testing libraries (e.g. Hypothesis, PropEr, Hedgehog, Validity): Shrinking for free [4], generators for free [5], defining the probability distribution of your sub-generators in a composable way. Maybe those features are not as significant, but they're equally missing from almost all property-test libaries. [4]: Gens N’ Roses: Appetite for Reduction • Jacob Stanley • YOW! 2017 https://www.youtube.com/watch?v=LfD0DHqpeVQ [5]: https://tech.fpcomplete.com/blog/quickcheck-hedgehog-validit...

In The sad state of property-based testing libraries