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 Control.Monad
  import System.Random.Stateful
  import Text.Printf
  
  -- | Whether a person passes a test.
  pass :: [Double] -> [Int]
  pass xs =
      map (\x ->
               if x < 0.75
                   then 0 :: Int
                   else 1 :: Int)
          xs
  
  -- | Simulate the test results for a given number of people.
  testResult :: Int -> IO [Double]
  testResult n = replicateM n $ uniformDouble01M globalStdGen
  
  -- | Simulate the fraction of people who pass a test.
  main = do
      let n = 100 :: Int
      result <- testResult n
      let npass = sum $ pass result
      let frac = (fromIntegral npass :: Double) / (fromIntegral n :: Double)
      printf "Fraction of passed: %f\n" frac
  