NFKC string normalization

normalize.hs

{-# Language JavaScriptFFI #-}
{-# Language OverloadedStrings #-}
import Data.Text (Text)
import qualified Data.Text as T

describeString :: Text -> String
describeString n = mconcat
  [ T.unpack n
  , " ("
  , show n
  , ")"
  ]

foreign import javascript safe
  "(function() { return ($1['normalize']('NFKC')); })()"
  normalize :: Text -> Text

main :: IO ()
main = do
  let n = "\xf1" :: Text
      n' = "\x6e\x303" :: Text
  putStrLn $ "Non-normalized 1: " <> describeString n
  putStrLn $ "Non-normalized 2: " <> describeString n'
  putStrLn $ "Are they equal? " <>
    if n == n'
      then "Yes"
      else "No"
  let normal = normalize n
      normal' = normalize n'
  putStrLn $ "Normalized 1: " <> describeString (normal)
  putStrLn $ "Normalized 2: " <> describeString (normal')
  putStrLn $ "Are they equal? " <>
    if normal == normal'
      then "Yes"
      else "No"