prefix-units
A basic library for SI/IEC prefix units
https://github.com/iustin/prefix-units
LTS Haskell 22.33: | 0.3.0.1@rev:1 |
Stackage Nightly 2024-09-07: | 0.3.0.1@rev:1 |
Latest on Hackage: | 0.3.0.1@rev:1 |
prefix-units-0.3.0.1@sha256:9ed174c705e2e5fd5dd191f3af17239ae18cd5cc4824ddb21b5875db033dba75,3780
Module documentation for 0.3.0.1
- Data
- Data.Prefix
prefix-units package
This package defines a datatype (Unit
) and associated
parsing/formatting functions so that command line applications can
handle “nice” values like:
$ cmd create-file foo 100G
Done.
$ cmd ls-file foo
Size is 100Gi
$ cmd ls-files
foo 100Gi
bar 14Ki
And so on. For details on the API, look at the Haddock documentation
for the Data.Prefix.Units
module.
For building and installing, cabal configure
and related commands
are enough. Run cabal configure --enable-tests && cabal build && cabal test
if you want to run the unit-tests.
The library is designed to have very few dependencies (only base and a few GHC extensions), so that it’s trivial to use it in projects. Hence the use of some hand-coded conversions instead of using TemplateHaskell to generate them automatically.
TODO
The current interface of the library works, but is not nicely composable. I’m still looking for a nicer way to expose the parsing functionality.
Currently, the IEC (binary) and SI units are mixed in the same data-type. This works, but at some level I think two separate types would be more “correct”, at the expense of a more complex API.
The RationalConvertible type class has only a few instances; ideally
we’d have instance Integral a => RationalConvertible a
and similar
for Fractional
, but this doesn’t work as such in Haskell, so we’re
stuck with the manual derivation.
The current behaviour is case-sensitive for all units in ParseExact
mode, which means that one has to use (in this mode) Ki
for the
binary unit Kibi
. This seems suboptimal, since the binary units are
unique irrespective of casing.
Changes
Version 0.3.0.1
released Thu, 27 Apr 2023
It turns out that even if cabal check
shows no warnings, Hackage
doesn’t accept packages with very old cabal version constraints. So
this release bumps that, which in turns makes cabal check
actually
start to show warnings, so modernise the cabal file as a result.
There are no code changes compared to 0.3.0, so this is a no-op release from the point of view of functionality.
Version 0.3.0
released Wed, 26 Apr 2023
- Add the new quecto/ronto/ronna/quetta units. I didn’t think I’d ever have to extend the list of units! Not sure entirely if these should be part of the parseKMGT function, since they’re high enough to be out of normal computer units, but they do have lower/upper versions, so adding them seems the right thing.
Version 0.2.0
released Sun, 22 Nov 2015
- Incompatible API change to cleanup some initial design decisions:
the two level
FormatOption
/FormatMode
model is removed, the fixed unit ofFormatOption
is moved to a new constructorFormatMode
, andFormatOption
is removed entirely. This should be a simpler API, at the cost of breaking compatibility. - Fixed issue #3 (No support for negative numbers).
- Worked around issue #1 (Add ‘base’ unit) by adding a mode that disables scaling; it should have the same effect without introducing an artificial unit.
Version 0.1.0.2
released Sun, 23 Nov 2014
- Trivial release for compatibility with QuickCheck 2.7 and older HUnit packages as found in Wheezy.
- The release switches the test suite to use Cabal macros, which might create issues in some cases.
- Fixed issue #2 (Wrong formatting for small numbers in SI mode).
Version 0.1.0.1
released Mon, 19 May 2014
- Trivial release updating upper package bounds (for testing), updating homepage/related settings as part of move to github, and fixing a few documentation issues.
Version 0.1.0
released Thu, 03 May 2012
- Initial release.