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
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  --------------------------------------------------------------------------------
  
  import Text.Printf
  
  -- | Addition for integer vectors of three elements.
  vadd :: Integral a => (a, a, a) -> (a, a, a) -> (a, a, a)
  vadd (s, t, u) (x, y, z) = (s + x, t + y, u + z)
  
  -- | Vector addition.
  main = do
      let a = 1 :: Integer
      let b = 2 :: Integer
      let c = 3 :: Integer
      let d = 4 :: Integer
      let s = 5 :: Int
      let t = 6 :: Int
      let u = 7 :: Int
      let v = 8 :: Int
      printf "(%d, %d, %d) + (%d, %d, %d) -> %s\n" a b c d (-b) (-d) $
          show $ vadd (a, b, c) (d, -b, -d)
      printf "(%d, %d, %d) + (%d, %d, %d) -> %s\n" s t (-t) (-v) u v $
          show $ vadd (s, t, -t) (-v, u, v)
  