| CARVIEW |
chronos: A high-performance time library
Chronos is a performance-oriented time library for Haskell, with a
straightforward API. The main differences between this
and the time library
are:
* Chronos uses machine integers where possible. This means
that time-related arithmetic should be faster, with the
drawback that the types are incapable of representing times
that are very far in the future or the past (because Chronos
provides nanosecond, rather than picosecond, resolution).
For most users, this is not a hindrance.
* Chronos provides ToJSON/FromJSON instances for serialisation.
* Chronos provides Unbox instances for working with unboxed vectors.
* Chronos provides Prim instances for working with byte arrays/primitive arrays.
* Chronos uses normal non-overloaded haskell functions for
encoding and decoding time. It provides attoparsec parsers for both Text and
ByteString. Additionally, Chronos provides functions for
encoding time to Text or ByteString. The https://hackage.haskell.org/package/time time> library accomplishes these with the
Data.Time.Format module, which uses UNIX-style datetime
format strings. The approach taken by Chronos is faster and
catches more mistakes at compile time, at the cost of being
less expressive.
[Skip to Readme]
Downloads
- chronos-1.1.7.0.tar.gz [browse] (Cabal source package)
- Package description (revised from the package)
Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.
Maintainer's Corner
For package maintainers and hackage trustees
Candidates
| Versions [RSS] | 0.1.0, 0.2.0, 0.3, 0.4, 1.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.0.6, 1.0.7, 1.0.8, 1.0.9, 1.1, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 1.1.5.1, 1.1.6.0, 1.1.6.1, 1.1.6.2, 1.1.7.0 |
|---|---|
| Change log | CHANGELOG.md |
| Dependencies | aeson (>=2.2 && <2.3), attoparsec (>=0.13 && <0.15), base (>=4.14 && <5), bytebuild (>=0.3.14 && <0.4), byteslice (>=0.2.5.2 && <0.3), bytesmith (>=0.3.7 && <0.4), bytestring (>=0.10 && <0.13), deepseq (>=1.4.4.0), hashable (>=1.2 && <1.6), natural-arithmetic (>=0.1.2 && <0.3), primitive (>=0.6.4 && <0.10), text (>=2.1.2 && <2.2), text-short (>=0.1.5 && <0.2), torsor (>=0.1 && <0.2), vector (>=0.11 && <0.14), Win32 (>=2.2 && <2.14) [details] |
| Tested with | ghc ==9.6.3 || ==9.8.1 |
| License | BSD-3-Clause |
| Copyright | 2016 Andrew Martin |
| Author | Andrew Martin |
| Maintainer | amartin@layer3com.com, chessai1996@gmail.com |
| Uploaded | by andrewthad at 2025-07-15T16:11:45Z |
| Revised | Revision 1 made by andrewthad at 2025-07-15T16:39:57Z |
| Category | Data, Time, Parsing, Development |
| Home page | https://github.com/byteverse/chronos |
| Bug tracker | https://github.com/byteverse/chronos/issues |
| Source repo | head: git clone git://github.com/byteverse/chronos.git |
| Distributions | LTSHaskell:1.1.7.0, NixOS:1.1.7.0, Stackage:1.1.7.0 |
| Reverse Dependencies | 26 direct, 31 indirect [details] |
| Downloads | 15564 total (132 in the last 30 days) |
| Rating | 2.0 (votes: 1) [estimated by Bayesian average] |
| Your Rating |
|
| Status | Docs available [build log] Last success reported on 2025-07-15 [all 1 reports] |
Readme for chronos-1.1.7.0
[back to package description]Chronos
Chronos is a performance-oriented time library for Haskell, with a straightforward API. The main differences between this and the time library are:
- Chronos uses machine integers where possible. This means that time-related arithmetic should be faster, with the drawback that the types are incapable of representing times that are very far in the future or the past (because Chronos provides nanosecond, rather than picosecond, resolution). For most users, this is not a hindrance and the tradeoff is worthwhile.
- Chronos provides 'ToJSON'/'FromJSON' instances for serialisation.
- Chronos provides 'Unbox' instances for working with unboxed vectors.
- Chronos provides 'Prim' instances for working with byte arrays/primitive arrays.
- Chronos uses normal non-overloaded haskell functions for encoding and decoding time. It provides attoparsec parsers for both 'Text' and 'ByteString'. Additionally, Chronos provides functions for encoding time to 'Text' or 'ByteString'. The time library accomplishes these with the Data.Time.Format module, which uses UNIX-style datetime format strings. The approach taken by Chronos is faster and catches more mistakes at compile time, at the cost of being less expressive.
Jacob Stanley has written
a blog post comparing the features and performance
of time, thyme, and chronos. It has a good bulleted breakdown of why
you may want to use each library along with some benchmarks.
Benchmarks
Benchmarks of chronos against time and thyme.
Parsing
| Benchmark name | Time |
|---|---|
| Time.parseTimeM | 9.679 μs |
| Thyme.parseTime | 1.743 μs |
| Thyme.timeParser | 1.113 μs |
| Chronos.parserUtf8_YmdHMS | 301.4 ns |
| Chronos.zeptoUtf8_YmdHMS | 173.6 ns |
Pretty-printing
| Benchmark name | Time |
|---|---|
| dmy/Time.formatTime | 4.404 μs |
| dmy/Thyme.formatTime | 663.0 ns |
| dmy/Chronos.builder_Dmy | 340.9 ns |
| HMS/Time.formatTime | 1.987 μs |
| HMS/Thyme.formatTime | 879.1 ns |
| HMS/Chronos.builder_HMS | 481.3 ns |
Doctest
Doctest used to be provided as a test suite, but doctest-0.20 and higher
do not require this to be run. To run the doctests, make sure you have
doctest on your path (i.e. run cabal install doctest), and then run:
cabal build
cabal repl --build-depends=QuickCheck --with-ghc=doctest --repl-options='-fno-warn-orphans'
This runs incredibly slowly, but it works for now. Doctest is not run by CI, so if you make a change that adds more doctests, it needs to be run by hand by someone. (The maintainer is happy to do this if you're on a platform where doctest is finicky.)