content: --------------------------------------------------------------------------------
  -- MIT License
  --
  -- Copyright (C) 2023 Duck McSouls <quacksouls [AT] gmail [DOT] com>
  --
  -- Permission is hereby granted, free of charge, to any person obtaining a copy
  -- of this software and associated documentation files (the "Software"), to deal
  -- in the Software without restriction, including without limitation the rights
  -- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  -- copies of the Software, and to permit persons to whom the Software is
  -- furnished to do so, subject to the following conditions:
  --
  -- The above copyright notice and this permission notice shall be included in
  -- all copies or substantial portions of the Software.
  --
  -- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  -- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  -- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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  --------------------------------------------------------------------------------
  
  import Data.Foldable
  import Data.List
  import Text.Printf
  
  -- | Database of pet names.
  pet =
      [ "Anonymouse"
      , "Cat Scan"
      , "Charlie Chihuahua"
      , "Chirpie O'Tweet"
      , "Dogalogue"
      , "Fido Dogstoevsky"
      , "Frankie Frankfurt"
      , "Garry Longtongue"
      , "Goldie Horn"
      , "Hamsuke Hamton"
      , "Harry Speedbump"
      , "Mrs. Clucky"
      , "Papa's New Guinea"
      , "Roam Ferret Roam"
      , "Robbie Hopster"
      , "Scratchy Meowser"
      , "Tabby Whiskers"
      , "Terry Terrier"
      , "Woofy McBark"
      ]
  
  -- | All pet names that start with a given prefix.
  startsWith :: String -> [String]
  startsWith str = filter (\x -> str `isPrefixOf` x) pet
  
  -- | Managing a pets database.
  main = do
      putStrLn "Names beginning with C"
      for_ (startsWith "C") $ \x -> printf "%s\n" x
      putStrLn "\nNames beginning with R"
      for_ (startsWith "R") $ \x -> printf "%s\n" x
  