Idris points the way to the future of programming.
A few examples that I find very intriguing:
1. type safe printf: https://github.com/mukeshtiwari/Idris/blob/master/Printf.idr
2. compile-time evidence that a runtime check will be performed: https://github.com/idris-lang/Idris-dev/blob/master/libs/bas...
3. Most of all, compile-time checking of state machine properties http://docs.idris-lang.org/en/latest/st/introduction.html
Think about being able to specify protocols in the type system and ensuring that your client and server meet the specifications. The example in that link is about user authentication. Imagine having a proof that the program can only get into a "LoggedIn" state by going through the authentication protocol.
In Things that Idris improves things over Haskellidris-lang
Idris-dev
Haskell2014–2020
idris-lang / Idris-dev · Archived
Idris-dev
A Dependently Typed Functional Programming Language
21Distinct people
21Mentions
0Explicit recommenders
3.5KGitHub stars
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What it is
A Dependently Typed Functional Programming Language
GitHub
Where it is used
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 8:59:20 PM UTC.
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Mentions over time
HN mentions by year21 dated mentions
Observed mentions: 2014-04-13 21:05:19 UTC to 2020-09-12 11:50:45 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2014 | 2014-01-01 00:00:00 UTC | 2015-01-01 00:00:00 UTC | 7 | 2 | 5 |
| 2015 | 2015-01-01 00:00:00 UTC | 2016-01-01 00:00:00 UTC | 3 | 0 | 3 |
| 2016 | 2016-01-01 00:00:00 UTC | 2017-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 2 | 0 | 2 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 2 | 0 | 2 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 5 | 0 | 5 |
From the project README
An excerpt from the repository, fetched Nov 13, 2026.
Read the project’s introduction
Idris 1
Idris (https://idris-lang.org/) is a general-purpose functional programming
language with dependent types.
Installation
This repository represents the latest development version of the
language, and may contain bugs that are being actively worked on. For
those who wish to use a more stable version of Idris please consider
installing the latest version that has been released on Hackage.
Installation instructions for various platforms can be
found on the Idris Wiki.
More information about building Idris from source has been detailed in the Installation Guide
Code Generation
Idris has support for external code generators. Supplied with the distribution
is a C code generator to compile executables, and a JavaScript code generator
with support for node.js and browser JavaScript.
More information about code generators can be found
here.
Status
This is Idris 1, implemented in Haskell. Idris 1 is not actively
worked on anymore.
Idris 2 is the next generation
of Idris, and where primary development happens.
More Information
If you would like to find out more information, or ask questions, we
currently have a Wiki;
a mailing list,
and an IRC channel #idris on libera. To join the IRC channel,
point your irc client to irc.libera.chat then /join #idris.
For those further interested in using Idris for projects, the
Idris Hackers GitHub organisation is
where some interesting projects are being hosted.
For those interested in contributing to Idris directly we kindly ask that
prospective developers please consult the Contributing Guide first.
Read the full README on GitHubWhat Hacker News says
2 sourcesI'm under the impression that SPJ made that comment thinking of adoption (for a future "regrettably popular" Haskell), since the difficulty of reasoning about laziness does put people off. I might be wrong though: maybe he was arguing that laziness doesn't warrant the user and compiler-author cost it brings. I don't remember where I picked this up from.
Idris is strict too, but optional laziness is built into the compiler with the use of a special-cased Lazy wrapper of the form
data Lazy a = Delay a
This is kind of the opposite of strictness annotations (bang-patterns) from Haskell, except one doesn't need to pattern-match on Delay or use it to wrap arguments to functions expecting Lazy values. The Idris compiler can do something like "laziness analysis" (admittedly trivial in comparison to GHC's strictness analyser) to introduce and e
Read the rest
liminate Delay constructors automatically. The laziness information is carried around in the types:
force : Lazy a -> a
force a = a
https://github.com/idris-lang/Idris-dev/wiki/Unofficial-FAQ#...
(purescript-lazy is also a thing, but I think it's not as seamless because of the "no compiler magic" position.)
In any case, what about -XStrict? I've never used it (or -XStrictData either), but isn't it a solution to the laziness problem, albeit a nuke-ish one at that?
And while we're thinking ahead, let's talk about the project to get linear types (something similar to Rust lifetimes, but weaker) into GHC :)
https://ghc.haskell.org/trac/ghc/wiki/LinearTypes