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haskell-servant
servant
Haskell2015–2023
haskell-servant / servant

servant

Servant is a Haskell DSL for describing, serving, querying, mocking, documenting web applications and more!

Web Development
Explore on GitHubRead Hacker News discussions
4Distinct people
4Mentions
0Explicit recommenders
2KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

Servant is a Haskell DSL for describing, serving, querying, mocking, documenting web applications and more!

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, 3:03:16 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 year4 dated mentions

Observed mentions: 2015-05-10 19:17:12 UTC to 2023-10-09 19:13:49 UTC.

0122015-01-01 00:00:00 UTC to 2016-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments20152016-01-01 00:00:00 UTC to 2017-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments20192020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2023

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
20152015-01-01 00:00:00 UTC2016-01-01 00:00:00 UTC202
20162016-01-01 00:00:00 UTC2017-01-01 00:00:00 UTC101
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC000
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC000
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC000
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC000
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC000
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC000
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC101

What Hacker News says

4 sources
crote·Oct 9, 2023
> do you really have to understand language extensions? You do when your code doesn't compile and you're trying to figure out what the error message means, or when the library you want to use makes heavy use of it for even basic functionality. > These days one just enables GHC2021 My experience was pre-GHC2021. I basically had to enable at a minimum 5-6 language extensions in every single file. > Mostly they're just about removing unnecessary restrictions from the older standard. Yeah, those ones are usually fine. I have zero objection to things like FlexibleInstances or DeriveFoldable. > Could you give an example? I believe I was trying to implement Central Authentication Service using Servant. However, that required returning a custom HTTP status code. There has been an open Github issue for this since 2017, but it seems to require basi
Read the rest
cally rewriting the entire framework: https://github.com/haskell-servant/servant/issues/732 Looking back at it now Servant does have "ServerError", but that basically requires giving up all the advantages Servant claims to have and I believe it was not a viable option at the time. Looking at the timeline I was probably also on Servant 0.15, and there seems to have been a rewrite since then. I vaguely recall running into a similar issue trying to interact with a database, but I can't remember the details of that.
In An alternative front end for Haskell?
crdb·Feb 9, 2016
For our last 2 clients (with both, offering a "data team as a service"): the reporting tools were written in Haskell, using Servant [1] which got started trying to do the same at Zalora to set up a customer service management tool. The motivation was that it made painful stuff much simpler and faster to write (performance was a bonus). It's also used for a bunch of tricky data manipulation problems that were harder to solve using pure SQL. Example: identify a unique customer based on attributes (email, phone, address, etc.) one or more of which can change when a customer tries to create a "new" profile to grab the $10 new customer signup voucher. This ran recursively on the entire customer dataset (12 countries, some customers had created as many as 250 profiles) in about 4 seconds on a m3.medium instance. We don't/didn't write blog posts
Read the rest
or tweets about it though. I think the set of people who write blog posts (i.e. both have free time to do so, the talent, and the motivation) is relatively small, and the number of blog posts and other visible stuff being published is proportional to the size of the community, so you'll see many more Node.js/RoR posts than you will on using set theory to reduce a 5,000-table flawed data model systematically or the kind of everyday stuff Haskellers are doing everywhere. Also, personally at least, I don't feel like I know enough to have much to offer by writing a blog, so I stick to making these semi-anonymous HN comments. Interviewing Haskellers, I found a lot of examples of similar work - CRUD tasks, web services, etc. built in Haskell within a larger organisation and running quietly in the background. Something small and modular that can be tacked on quietly. One of the creators of Servant moved on to Tweag [2], a French big data company, where he's working on PB-size distributed machine learning projects for large corporate clients, which I think is where Haskell really shines today. I suspect NDAs will stop them from talking much about it... I've always wanted to do similar work for clients but so far, no dataset was "big" enough to justify moving away from well established R libraries. [1] https://github.com/haskell-servant/servant [2] http://www.tweag.io/
In The Evolution of a Haskell Programmer (2001)
jkarni·May 10, 2015
We had QQ originally, but removed it because it wasn't extensible (you can define new expressions in the type-level DSL, but you couldn't add them to the QQ). We've figured out how to do that now, and there's an issue someone opened asking for it back (https://github.com/haskell-servant/servant/issues/55), so it'll probably soon return. You do get kind of used to it, though, for what it's worth. And you can always break things up. E.g.: type MyAPI = "users" :> Get '[JSON] User :<|> "users" :> ReqBody '[JSON] User :> Post '[] () Can generally be rewritten as: type GetUser = Get '[JSON] User type PostUer = ReqBody '[JSON] User :> Post '[] () type MyAPI = "user" :> (GetUser :<|> PostUser) etc.
In Show HN: Servant – A Haskell web framework with type-level API DSL

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