JSのように簡潔にレコードをつくる方法

追記 2023.07.25

RIOのREADMEに、詳細は追ってませんが、次のような注記あり。

RecordWildCards is really up for debate. It's widely used, but rightfully considered by many to be dangerous. Open question about what we do with it.

---

(以下原文)

RecordWildCards 拡張を導入すると次のような簡潔な方法でデータを生成できる。

#!/usr/bin/env stack
-- stack --resolver lts-20.7 script

{-# LANGUAGE RecordWildCards #-}

data MyData = MyData
  { foo :: !String
  , bar :: !String
  } deriving (Show)

main :: IO ()
main = do
  let foo = "Foo"
  let bar = "Bar"
  let myData = MyData {..}
  print myData -- Output: MyData {foo = "Foo", bar = "Bar"}

参考文献

• https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/record_wildcards.html