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co-log-core: Composable Contravariant Comonadic Logging Library

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This package provides core types and functions to work with the LogAction data type which is both simple and powerful.

newtype LogAction m msg = LogAction
    { unLogAction :: msg -> m ()
    }

The ideas behind this package are described in the following blog post:

See the following packages for different implementations based on co-log-core:

  • co-log: taggless final implementations.

  • co-log-polysemy: extensible effects implementation based on polysemy.

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Versions [RSS] 0.0.0, 0.1.0, 0.1.1, 0.2.0.0, 0.2.1.0, 0.2.1.1, 0.3.0.0, 0.3.1.0, 0.3.2.0, 0.3.2.1, 0.3.2.2, 0.3.2.3, 0.3.2.4, 0.3.2.5
Change log CHANGELOG.md
Dependencies base (>=4.10.1.0 && <4.15) [details]
Tested with ghc ==8.2.2, ghc ==8.4.4, ghc ==8.6.5, ghc ==8.8.3, ghc ==8.10.1
License MPL-2.0
Copyright 2018-2020 Kowainik
Author Dmitrii Kovanikov
Maintainer Kowainik <xrom.xkov@gmail.com>
Revised Revision 1 made by shersh at 2020-06-03T10:30:16Z
Category Logging, Contravariant, Comonad
Home page https://github.com/kowainik/co-log
Bug tracker https://github.com/kowainik/co-log/issues
Source repo head: git clone https://github.com/kowainik/co-log.git
Uploaded by shersh at 2020-04-18T20:12:25Z
Distributions Arch:0.3.2.4, LTSHaskell:0.3.2.5, NixOS:0.3.2.2, Stackage:0.3.2.5
Reverse Dependencies 27 direct, 59 indirect [details]
Downloads 10545 total (17 in the last 30 days)
Rating 2.5 (votes: 3) [estimated by Bayesian average]
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Status Docs uploaded by user
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Readme for co-log-core-0.2.1.1

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co-log

GitHub CI Build status Windows build MPL-2.0 license
co-log-core Hackage Stackage LTS Stackage Nightly
co-log Hackage Stackage LTS Stackage Nightly
co-log-polysemy Hackage Stackage LTS Stackage Nightly

co-log is a composable and configurable logging framework. It combines all the benefits of Haskell idioms to provide a reasonable and convenient interface. Though it uses some advanced concepts in its core, we are striving to provide beginner-friendly API. The library also contains complete documentation with a lot of beginner-friendly examples, explanations and tutorials to guide users. The combination of a pragmatic approach to logging and fundamental Haskell abstractions allows us to create a highly composable and configurable logging framework.

If you're interested in how different Haskell typeclasses are used to implement core functions of co-log, you can read the following blog post which goes into detail about internal implementation specifics:

co-log is also modular on the level of packages. We care a lot about a low dependency footprint so you can build your logging only on top of the minimal required interface for your use-case. This repository contains the following packages:

  • co-log-core: lightweight package with basic data types and general idea which depends only on base.
  • co-log: taggless final implementation of logging library based on co-log-core.
  • co-log-polysemy: implementation of logging library based on co-log-core and the polysemy extensible effects library.
  • co-log-benchmark: benchmarks of the co-log library.

To provide a more user-friendly introduction to the library, we've created the tutorial series which introduces the main concepts behind co-log smoothly:

co-log also cares about concurrent logging. For this purpose we have the concurrent-playground executable where we experiment with different multithreading scenarios to test the library's behavior. You can find it here:

Benchmarks

co-log is compared with basic functions like putStrLn. Since IO overhead is big enough, every benchmark dumps 10K messages to output. If a benchmark's name doesn't contain Message then this benchmark simply dumps the string "message" to output, otherwise it works with the Message data type from the co-log library.

To run benchmarks, use the following command:

cabal v2-run co-log-bench
Benchmarks Time for 10K messages
Prelude.putStrLn 5.117ms
Text.putStrLn 9.220ms
ByteString.putStrLn 2.971ms
mempty 1.181ms
logStringStdout 5.107ms
logPrint 5.248ms
logTextStdout 5.351ms
logByteStringStdout 2.933ms
logByteStringStderr 17.482ms
ByteString > (stdout <> stderr) 17.715ms
Message > format > stdout 9.188ms
Message > format > ByteString > stdout 3.524ms
Message{callstack} > format > stdout 9.139ms
Message{callstack:5} > format > stdout 9.464ms
Message{callstack:50} > format > stdout 9.439ms
Message{Time,ThreadId} > format > stdout 54.160ms
Message{Time,ThreadId} > format > ByteString > stdout 54.137ms