Could not find module ‘Test.QuickCheck’ on Windows

Question

My ghci version is 8.4.3

I tried

stack install QuickCheck

Something was installed. But when I input import Test.QuickCheck, it tells Could not find module ‘Test.QuickCheck’ again. How can I fix it?

Answer 1

Firstly, stack install is not recommended for installing executables or libraries. Instead, there's a couple of things you can do to use the QuickCheck library:

• If you want to use QuickCheck in a command such as stack ghci or stack ghc, you can add it as a --package option e.g. to run a REPL to play around with QuickCheck you can use stack ghci --package QuickCheck and then write import Test.QuickCheck.
• If you want to write a small one-file program using QuickCheck, then you can run stack ghc --package QuickCheck -- MyProgram.hs (using the --package option from the last bullet point). Alternately, you can use stack's scripting functionality and include a line such as this at the top of your program: -- stack --resolver lts-12.18 script --package QuickCheck
• If you want to use QuickCheck in a large project, then add it as a dependency in your my-program.cabal or project.yaml file.

The same guidance applies to any package you may want to use.

Answer 2

myos>cabal update
myos>cabal install --lib QuickCheck
myos>ghci
gchi> import Test.QuickCheck