找不到模块“ Criterion.Main”

Question

I have copied the following code from criterion tutorial:

import Criterion.Main

-- The function we're benchmarking.
fib m | m < 0     = error "negative!"
      | otherwise = go m
  where
    go 0 = 0
    go 1 = 1
    go n = go (n-1) + go (n-2)

-- Our benchmark harness.
main = defaultMain [
  bgroup "fib" [ bench "1"  $ whnf fib 1
               , bench "5"  $ whnf fib 5
               , bench "9"  $ whnf fib 9
               , bench "11" $ whnf fib 11
                ]
     ]

I am getting the following error:

fiber.hs:1:1: error: Could not find module 'Criterion.Main' Use -v to see a list of the files searched for. | 1 | import Criterion.Main | ^^^^^^^^^^^^^^^^^^^^^

The GHC version I am using is 8.4.2 and cabal version is 2.2.0.0.

I tried to install the criterion package by:

cabal update
Downloading the latest package list from hackage.haskell.org
To revert to previous state run: cabal update --index-state='2018-06- 
01T04:23:08Z'

cabal install -j --disable-tests criterion
clang: warning: argument unused during compilation: '-nopie' [-Wunused- 
command-line-argument]
.
.
.
.
cabal: Error: some packages failed to install:
abstract-deque-0.3-IvBVpgU2tvq3eILHsBTjFR failed during the building 
phase.
The exception was:
ExitFailure 1
aeson-1.3.1.1-J9Jy9Bz77dxJho59OWZvUt depends on aeson-1.3.1.1 which 
failed to install.
attoparsec-0.13.2.2-5fvnJr9WRPCJj7fMCLKoI7 depends on attoparsec- 
0.13.2.2
which failed to install.
cassava-0.5.1.0-CNxiRQP2h44BSkY7PLw3nv depends on cassava-0.5.1.0 which 
failed
to install.
criterion-1.4.1.0-1CDqJgx5SYk1Xphp8S6hvK depends on criterion-1.4.1.0 
which failed to install.
microstache-1.0.1.1-DUzquwnO02sC17piNr03EI depends on microstache- 
1.0.1.1 which failed to install.
monad-par-0.3.4.8-5Qx7yEAZEkjJbqZykcUjIa depends on monad-par-0.3.4.8 
which failed to install.
monad-par-extras-0.3.3-755mClpwIBoBMORFcN7gCY failed during the 
building phase. The exception was:
ExitFailure 1
scientific-0.3.6.2-65wDZeAE9ZIBkaesoEq4I0 failed during the building 
phase.
The exception was:
ExitFailure 1
statistics-0.14.0.2-GHJ1OiovyXP1FEjV1emzr8 depends on statistics- 
0.14.0.2 which failed to install.
text-short-0.1.2-JRY9FeZhxkoAZrj3rm5IJZ failed during the building 
phase. The exception was:
ExitFailure 1
uuid-types-1.0.3-tE9Bfk2PgXDUPgbtamBdI failed during the building 
phase. The exception was:
ExitFailure 1

Answer 1

One approach would be to use the Stack script interpreter to run this. In order to do so, you would first install Stack , then add the script interpreter bits to the top of your file, eg:

#!/usr/bin/env stack
-- stack --resolver lts-11.10 script --optimize
import Criterion.Main

-- The function we're benchmarking.
fib m | m < 0     = error "negative!"
    | otherwise = go m
where
    go 0 = 0
    go 1 = 1
    go n = go (n-1) + go (n-2)

-- Our benchmark harness.
main = defaultMain [
bgroup "fib" [ bench "1"  $ whnf fib 1
            , bench "5"  $ whnf fib 5
            , bench "9"  $ whnf fib 9
            , bench "11" $ whnf fib 11
                ]
    ]

Note that I added the --optimize option on the second line to ensure that Stack would compile your code with optimizations on, instead of the default of using runghc .

And finally run the file with stack fiber.hs (or whatever you called the file).