e9571-config-reader-haskell: Automatically read config.json from the current directory

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Zero-configuration JSON config loader

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Properties

Versions	0.1.0.0, 0.1.0.0, 0.1.0.1, 0.1.0.2
Change log	None available
Dependencies	aeson (>=2.0 && <2.3), base (>=4.14 && <5), bytestring, directory, e9571-config-reader-haskell [details]
License	MIT
Author	e9571
Maintainer	95714623@qq.com
Category	Configuration
Home page	https://github.com/e9571/e9571-config-reader-haskell
Uploaded	by e9571 at 2025-11-26T01:15:27Z

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E9571
- E9571.ConfigReader

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e9571-config-reader-haskell-0.1.0.0.tar.gz [browse] (Cabal source package)
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Readme for e9571-config-reader-haskell-0.1.0.0

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e9571-config-reader-haskell

A tiny, zero-configuration Haskell library that instantly reads a config.json file from the current working directory.

Out-of-the-box, no setup required.
Just drop a config.json file next to your executable and start using the library — it just works.

Usage (two steps)

Create a config.json file in the same directory as your program:
```
{
  "host": "127.0.0.1",
  "port": 8080
}
```

   {-# LANGUAGE OverloadedStrings #-}
   
   import E9571.ConfigReader
   import Data.Aeson
   
   data Config = Config { host :: String, port :: Int } deriving Show
   
   instance FromJSON Config where
       parseJSON = withObject "Config" $ \o -> Config
           <$> o .: "host"
           <*> o .: "port"
   
   main :: IO ()
   main = do
       cfg <- loadConfigOrDie :: IO Config   -- automatically reads ./config.json
       putStrLn $ "Server starting at " ++ host cfg ++ ":" ++ show (port cfg)

Features

Automatically looks for ./config.json at runtime
No file paths, no command-line flags, no environment variables
Works with any FromJSON instance
Helpful error messages when the file is missing or malformed
Only depends on aeson

Installation

cabal install e9571-config-reader-haskell

Source: https://github.com/e9571/e9571-config-reader-haskell Hackage: https://hackage.haskell.org/package/e9571-config-reader-haskell

Enjoy the simplicity!