https://github.com/glguy/config-schema

Self-documenting, combinator constructed configuration schemas
https://github.com/glguy/config-schema

configuration haskell schema

Last synced: 3 months ago
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Self-documenting, combinator constructed configuration schemas

• Host: GitHub
• URL: https://github.com/glguy/config-schema
• Owner: glguy
• License: isc
• Created: 2017-05-05T20:37:41.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2023-11-21T16:51:00.000Z (about 1 year ago)
• Last Synced: 2024-05-08T20:13:47.713Z (8 months ago)
• Topics: configuration, haskell, schema
• Language: Haskell
• Homepage:
• Size: 129 KB
• Stars: 7
• Watchers: 4
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: ChangeLog.md
  • License: LICENSE

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README

        
config-schema

=============

[![Hackage](https://img.shields.io/hackage/v/config-schema.svg)](https://hackage.haskell.org/package/config-schema)

Live Demo

--------

The config-value and config-schema packages are available in a [live demo](https://glguy.net/config-demo/).

About

--------

This package allows the user to define configuration schemas suitable for

matching against configuration files written in the

[config-value](https://hackage.haskell.org/package/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.

```haskell

{-# 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"

```