Unicode Shenanigans

unicodeshenanigans.hs

{-# LANGUAGE OverloadedStrings #-}
module Lib
    ( someFunc
    ) where

import           Data.Aeson
import           Data.Aeson.Parser        (value)
import           Data.Aeson.Text
import           Data.Aeson.Types
import qualified Data.ByteString.Lazy     as BL
import           Data.Proxy               (Proxy (..))
import           Data.Text
import qualified Data.Text.IO             as TIO
import qualified Data.Text.Lazy           as TL
import           Data.Text.Lazy.Encoding
import           Servant.API.ContentTypes (JSON, mimeRender, mimeUnrender)

newtype MyText = MyText { unMyText :: Text } deriving (Show)

instance ToJSON MyText where
  toJSON (MyText txt) = object ["myText" .= txt]

instance FromJSON MyText where
  parseJSON (Object v) = MyText <$> v .: "myText"
  parseJSON v          = typeMismatch "MyText" v

someFunc :: IO ()
someFunc = do
  let x = MyText "\229 - å" -- these two characters are the same, == "å - å"
      encoded   = encode x                    :: BL.ByteString
      decoded   = decode encoded              :: Maybe MyText
      jsonType  = Proxy :: Proxy JSON
      mimed     = mimeRender jsonType x
      unmimed   = mimeUnrender jsonType mimed :: Either String MyText
  TIO.putStrLn $ unMyText x
  print ("default encoding/decoding path", encoded, decoded)
  print ("servant encoding/decoding path", mimed, unmimed)

{-
å - å
("default encoding/decoding path","{\"myText\":\"\195\165 - \195\165\"}",Just (MyText {unMyText = "\229 - \229"}))
("servant encoding/decoding path","{\"myText\":\"\195\165 - \195\165\"}",Right (MyText {unMyText = "\229 - \229"}))
-}