How to share module using Stack-CodePudding

My project structure:

MyProj
    app
    benchmarks
        Investigate.hs
    src
    test
        Example1.hs -- defines module Example1

My current package.yaml (simplified):

name: proj

dependencies:
- base >= 4.7 && < 5

library:
  source-dirs: src

executables:
  proj-exe:
    main: Main.hs
    source-dirs: app
    dependencies: proj

tests:
  proj-test:
    main: Spec.hs
    source-dirs: test
    dependencies: proj

benchmarks:
  investigate:
    main: benchmarks/Investigate.hs
    dependencies: proj

I want to import a module (say Example1 that lives under test, and use it in Investigate.hs under benchmarks. I am using stack, so how exactly do I configure my package.yaml?

CodePudding user response：

The obvious thing to do is to add an additional internal (private) library block to your package and put the shared code there, where it can be added to the dependencies of both your tests and benchmarks.

Or you could make a separate folder of utility code for tests and benchmarks, and then include that folder in the source-dirs list of both; there's nothing stopping a single folder being referenced in the source-dirs of multiple components (although the downside is any files within will be compiled separately for each component, not compiled once and then shared).

I don't use stack, so I don't know precisely how either of these things manifest in their package.yaml syntax, but they are features of cabal-the-library, so I'm pretty sure stack should support them.

CodePudding user response：

Notice that when you use dependecies: proj you are saying "This executable depends on the library proj"; and library proj lives within src as you specified. If you want to use a function in benchmarks and test suites, you should add it to a module within the library source directories: src. Below your package.yaml with comments. I also included a wrong line at the end so it is clear why you must put the functionality under src.

name: proj  # This is the name of the library. Generally one library per project. You can use you `stack.yaml` to define more.

dependencies:
- base >= 4.7 && < 5

library:  # Here is where the library functionality lives.
  source-dirs: src  

executables:           # This is your executable
  proj-exe:
    main: Main.hs
    source-dirs: app   # Living under app directory
    dependencies: proj # Which depends on the library. Which lives under src

tests:                 # This is your test suit
  proj-test:
    main: Spec.hs
    source-dirs: test  # Living under test directory
    dependencies: proj # Which depends on the library. Which lives under src

benchmarks:    # This is your benchmark. If you want to use a function living in 
  investigate: # the test folder, you would add it to the dependencies... but that's not allowed!!
    main: benchmarks/Investigate.hs
    dependencies: 
      - proj      # dependency on the library proj living under src
      - proj-test # This isn't allow because proj-test is not a library, is a test suite