Haskell to-do list with BlockArguments and Writer

haskell-to-do.hs

list :: [Task Text]
list = to do
  (□) "milk"
  (□) "eggs"
  (✓) "orange juice"

data Task a = Done a | Todo a deriving (Show)

to = execWriter

(✓) task = tell [Done task]

{-# LANGUAGE BlockArguments, FlexibleContexts, OverloadedStrings #-}
module Todo (list) where

import Data.Text (Text)
import Control.Monad.Writer (execWriter, tell)

list :: [Task Text]
list = to do
  (□) "milk"
  (□) "eggs"
  (✓) "orange juice"

data Task a = Done a | Todo a deriving (Show)

to = execWriter

(✓) task = tell [Done task]
(□) task = tell [Todo task]

naldoco@mm todo $ stack exec -- ghci src/Todo.hs test/TodoSpec.hs
GHCi, version 8.10.7: https://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /home/naldoco/.ghc/ghci.conf
[1 of 2] Compiling Todo ( src/Todo.hs, interpreted )
[2 of 2] Compiling TodoSpec ( test/TodoSpec.hs, interpreted )
Ok, two modules loaded.
: list
[Todo "milk",Todo "eggs",Done "orange juice"]