Haskell Criterion Usage Error

Question

The following code named fib.hs

import Criterion.Main (defaultMain)
fibZ = 1:1:zipWith (+) fibZ (tail fibZ)
main = defaultMain [
         bench "fibZ 10" $ \n -> fibZ (10+n-n)
       ]

errors with

fib.hs:45:10: Not in scope: `bench'

What is wrong? I have borrowed this example from here.

Answer 1

The library has changed since that blog post was written. Now you should write:

 import Criterion.Main

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

 main = defaultMain [
        bgroup "fib" [ bench "fib 10" $ B fib 10
                     , bench "fib 35" $ B fib 35
                     , bench "fib 37" $ B fib 37
                     ]
                    ]

This was taken directly from the "Running benchmarks" section of the Hackage documentation for Criterion.Main.