I cant import System.Directory when using stack

问题

I am little confused about why this doesn't work.

I have a small program that import System.Directory. When I run it with runhaskell on the command line it compiles and outputs what I expect.

When I use the same program with stack I get a message saying

Failed to load interface for ‘System.Directory’ It is a member of the hidden package ‘directory-1.3.0.0’. Use -v to see a list of the files searched for.

I dont understand why it would work with runhaskell but not when i use stack ghci

回答1:

With the information you give, I can only attempt a guess…

I think you have directory (globally) installed with cabal install directory or as a system package - this would explain runhaskell myscript.hs working.

if you use stack you have the following options.

1. make a cabal package, add directory to the build depends section, create a stack.yaml and run stack ghci inside the project directory.

2. use stack ghci --package=directory myscript.hs

来源：https://stackoverflow.com/questions/46260461/i-cant-import-system-directory-when-using-stack