config-schema: Schema definitions for the config-value package

[ language, library ] [ Propose Tags ]

This package makes it possible to define schemas for use when loading configuration files using the config-value format. These schemas can be used to process a configuration file into a Haskell value or to automatically generate documentation for the file format.


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Versions [faq] 0.1.0.0, 0.2.0.0, 0.3.0.0, 0.3.1.0, 0.3.1.1, 0.4.0.0, 0.4.1.0, 0.5.0.0, 0.5.0.1, 1.0.0.0, 1.1.0.0, 1.2.0.0, 1.2.1.0
Change log ChangeLog.md
Dependencies base (>=4.9 && <4.15), config-value (==0.8.*), containers (>=0.5 && <0.7), free (>=4.12 && <5.2), kan-extensions (>=5.0.2 && <5.3), pretty (>=1.1.2 && <1.2), semigroupoids (>=5.1 && <5.4), text (==1.2.*), transformers (>=0.4 && <0.6) [details]
License ISC
Copyright Eric Mertens 2017
Author Eric Mertens
Maintainer emertens@gmail.com
Category Language
Home page https://github.com/glguy/config-schema
Bug tracker https://github.com/glguy/config-schema/issues
Source repo head: git clone https://github.com/glguy/config-schema
Uploaded by EricMertens at 2020-09-26T18:23:31Z
Distributions Debian:0.5.0.1, NixOS:1.2.1.0
Downloads 6953 total (255 in the last 30 days)
Rating 2.0 (votes: 1) [estimated by Bayesian average]
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2020-09-26 [all 1 reports]

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Readme for config-schema-1.2.1.0

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config-schema

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Live Demo

The config-value and config-schema packages are available in a live demo.

About

This package allows the user to define configuration schemas suitable for matching against configuration files written in the config-value format. These schemas allow the user to extract an arbitrary Haskell value from an interpretation of a configuration file. It also allows the user to programatically generate documentation for the configuration files accepted by the loader.

{-# Language OverloadedStrings, ApplicativeDo #-}
module Example where

import qualified Data.Text as Text
import           Data.Text (Text)
import           Data.Monoid ((<>))
import           Data.Functor.Alt ((<!>))
import           Data.List.NonEmpty (NonEmpty)

import           Config
import           Config.Schema

exampleFile :: Text
exampleFile =
  " name: \"Johny Appleseed\" \n\
  \ age : 99                  \n\
  \ happy: yes                \n\
  \ kids:                     \n\
  \   * name: \"Bob\"         \n\
  \   * name: \"Tom\"         \n"

exampleValue :: Value Position
Right exampleValue = parse exampleFile

exampleSpec :: ValueSpec Text
exampleSpec = sectionsSpec "" $
  do name  <- reqSection  "name" "Full name"
     age   <- reqSection  "age"  "Age of user"
     happy <- optSection' "happy" yesOrNo
              "Current happiness status"
     kids  <- reqSection' "kids"  (oneOrList kidSpec)
              "All children's names"

     return $
       let happyText = case happy of Just True  -> " and is happy"
                                     Just False -> " and is not happy"
                                     Nothing    -> " and is private"

       in name <> " is " <> Text.pack (show (age::Integer)) <>
             " years old and has kids " <>
             Text.intercalate ", " kids <>
             happyText

kidSpec :: ValueSpec Text
kidSpec = sectionsSpec "kid" (reqSection "name" "Kid's name")


-- | Matches the 'yes' and 'no' atoms
yesOrNo :: ValueSpec Bool
yesOrNo = True  <$ atomSpec "yes" <!>
          False <$ atomSpec "no"


printDoc :: IO ()
printDoc = print (generateDocs exampleSpec)
-- *Example> printDoc
-- Top-level configuration file fields:
--     name: REQUIRED text
--        Full name
--     age: REQUIRED integer
--        Age of user
--     happy: `yes` or `no`
--        Current happiness status
--     kids: REQUIRED kid or list of kid
--        All children
--
-- kid
--     name: REQUIRED text
--        Kid's name

example :: Either (NonEmpty (LoadError Position)) Text
example = loadValue exampleSpec exampleValue
-- *Example> exampleVal
-- Right "Johny Appleseed is 99 years old and has kids Bob, Tom and is happy"