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
  -- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  -- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  -- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  -- SOFTWARE.
  --------------------------------------------------------------------------------
  
  import Text.Printf
  
  -- | Reverse a list via a fold.
  rvrs :: [a] -> [a]
  rvrs [] = []
  rvrs xs = foldl (\acc x -> x : acc) [] xs
  
  -- | Reverse a list.
  main = do
      let a = [1]
      let b = [1, 2, 3]
      let c = "abc"
      let d = "radar"
      let e = []
      let testa = reverse a == rvrs a
      let testb = reverse b == rvrs b
      let testc = reverse c == rvrs c
      let testd = reverse d == rvrs d
      printf "%s -> %s: %s\n" (show a) (show $ rvrs a) $ show testa
      printf "%s -> %s: %s\n" (show b) (show $ rvrs b) $ show testb
      printf "%s -> %s: %s\n" (show c) (show $ rvrs c) $ show testc
      printf "%s -> %s: %s\n" (show d) (show $ rvrs d) $ show testd
  