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'
Doctest now runs as part of CI.