What are some examples of using Criterion in Haskell?

Can you give me some examples of using Criterion in Haskell?

Sure! Criterion is a powerful library for benchmarking in Haskell. Would you like to see a simple example?

Yes, please show me a basic benchmarking example.

Here's a simple example: You can benchmark a function like this:

import Criterion.Main

main :: IO ()
main = defaultMain [
    bgroup "example"
        [ bench "fib 20" $ whnf fib 20,
          bench "fib 30" $ whnf fib 30
        ]
]

fib :: Integer -> Integer
fib 0 = 0
fib 1 = 1
fib n = fib (n - 1) + fib (n - 2)

What does whnf mean in this context?

whnf stands for 'weak head normal form'. It evaluates the expression to the outermost constructor, which is useful for benchmarking.