Random in Haskell

In Haskell, to generate random numbers, you need to make use of the random module that provides a typeclass RandomGen. This typeclass provides a random function that generates a random number and returns a new RandomGen generator, which can be used to generate the next random number.

Here's an example of how to generate a random number using System.Random module:

import System.Random
main :: IO ()

main = do

  gen <- newStdGen                    -- create a new RNG seed

  let randomNum = fst $ random gen :: Int  -- generate a random number

  print randomNum                    -- display the generated number

In this example, we use the newStdGen function to create a new random number generator. Next, we generate a random number using the random function, which takes a random number generator as input, and produces a random number of the specified type. In this case, we use Int as the type of random number.

Another example using the randomR function to generate a random number within a given range:

import System.Random
main :: IO ()

main = do

  gen <- newStdGen                      -- create a new RNG seed

  let (randInt, _) = randomR (1, 10) gen :: (Int, StdGen) -- generate a random number between 1 and 10

  print randInt                          -- display the generated number

In this example, we use the randomR function to generate a random number within a specific range. The function takes two arguments, a tuple containing the lower and upper bounds of the range, and the random number generator. And fst function selects the first value (i.e., the generated random number) from the tuple returned by randomR.