So don't write quicksort in Idris. It's not going to work very well anyways. It's not at all well-suited, and isn't really even an especially important sorting algorithm in a world where linear time sorting and constant time indexed searches are a thing.
But most of the work you'd be doing to write quicksort is writing the machinery for structurally recursive sorting, which a lot of tutorials write not because you have to, but because it's a very good exercise for learning how to write total functions that are recursive in a way DT systems can prove totality on.
Most of these tools are in the contrib library (and the book mentions this). For example the preorder interface you need:
https://github.com/idris-lang/Idris-dev/blob/master/libs/con...
In The Little Typeridris-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 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 1:57:11 AM 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 GitHub