Add Data.Map (containers-0.6.2.1) to common dependencies

[artamonovkirill]

If my solution (e.g., the Grade School) imports Data.Map, the test runner fails with:

/mnt/exercism-iteration/src/School.hs:4:1: error:
    Could not load module 'Data.Map'
    It is a member of the hidden package 'containers-0.6.2.1'.
    Perhaps you need to add 'containers' to the build-depends in your .cabal file.

Given that Data.Map is the 3rd most popular import (see #1006), would be nice to have it imported by default.

[artamonovkirill]

@ErikSchierboom

[ErikSchierboom]

@petertseng Is this the same issue described in #1006? Or is containers a dependency we need to add to the test runner's precompiled dependencies list: https://github.com/exercism/haskell-test-runner/blob/main/pre-compiled/package.yaml#L11?

[petertseng]

The presence of containers in https://downloads.haskell.org/~ghc/9.0.1/docs/html/libraries/index.html tells us that GHC already comes with containers. Thus adding it to https://github.com/exercism/haskell-test-runner/blob/main/pre-compiled/package.yaml#L11 changes nothing. This is not related #1006. #1006's error was Cabal file info not found which as we can see is not the error described in this issue.

My advice is is that we have the same two possibilities as #1006 (comment), but I will modify that comment to be applicable to this situation.

• We could expect that the student should submit the package.yaml that includes containers under dependencies, just like how we expect that if students use any dependencies they submit package.yaml. This is the status quo. If this is the decision, the action is to close this issue and do nothing more.
• Or we could add containers to https://github.com/exercism/haskell/blob/main/exercises/practice/grade-school/package.yaml, presuming that every student who wants to solve this exercise will use it. I think that is a fine presumption. The main alternative to not using containers would be to use association lists and e.g. https://hackage.haskell.org/package/base-4.16.0.0/docs/Prelude.html#v:lookup, and the code would not look particularly pleasant. If this is the decision, the action is to submit such a PR, which I would approve as long as it sufficiently summarises the above reasoning ("The main alternative to not using containers...") and links to this issue using a word in https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue.

[artamonovkirill]

@petertseng submitting package.yaml works fine with the CLI, but not in the online editor.

@ErikSchierboom are there currently any tracks that allow editing multiple files in the online editor or that allow to add extra libraries in some other way?

[ErikSchierboom]

The C/C++ tracks have both a .h and a .c/.cpp file the student can edit. There is no special way to add extra libraries.

[artamonovkirill]

Should then package.yaml be editable online for (some) Haskell exercises?

[ErikSchierboom]

Possibly, yes

[isaacvando]

Now that the online editor supports editing the package.yaml file (per #1080), I think it could be a good time to close this issue.

It seems more consistent to me to not include containers in the package.yaml file. If I was new to the track and didn't know about adding dependencies to package.yaml, it would be quite frustrating that importing Data.Map worked for grade-school but none of the other problems that didn't have containers added already.

[artamonovkirill]

Thanks for the update and sorry for taking so long to reply.

I can edit package.yaml online, and specifying containers dependency without a version.

But adding a version constrain (containers >= 0.6.3) breaks the build:

No information from Hackage index, updating
Selected mirror https://hackage.haskell.org/
Downloading root
HttpExceptionRequest Request {
  host                 = "hackage.haskell.org"
  port                 = 443
  secure               = True
  requestHeaders       = [("Accept-Encoding",""),("User-Agent","Haskell pantry package")]
  path                 = "/root.json"
  queryString          = ""
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (ConnectionFailure Network.Socket.getAddrInfo (called with preferred socket type/protocol: AddrInfo {addrFlags = [AI_ADDRCONFIG], addrFamily = AF_UNSPEC, addrSocketType = Stream, addrProtocol = 0, addrAddress = <assumed to be undefined>, addrCanonName = <assumed to be undefined>}, host name: Just "hackage.haskell.org", service name: Just "443"): does not exist (Try again))

If I remember correctly, the test runner does not have Internet access when running the tests.
If so, how do I know which packages / versions are available at the runtime?

[MatthijsBlom]

The exercises use a Stackage snapshot. stack.yaml specifies which one. It looks like this isn't visible in the web editor, but when you really need to know you can find it in the track repo: example. (Likely all exercises use 18.14 right now.)

The versions included in a snapshot are listed on Stackage.

[artamonovkirill]

There's already a little comment explaining adding dependencies:

  # dependencies:
  # - foo       # List here the packages you
  # - bar       # want to use in your solution.

Would it be too much information to add a disclaimer that just any version would not work? And/or a short explanation about Stackage, maybe with some links?

[MatthijsBlom]

# dependencies:
  # - foo       # List here the packages you
  # - bar       # want to use in your solution.
                # Do not specify version bounds!
                # Versions are derived from the Stackage snapshot.
                # You can find your snapshot in `stack.yaml`.
                # The package versions are listed on the corresponding
                # web page. Example:  www.stackage.org/lts-18.14

I feel this becomes a lot, fast. I'm fine with the Do not specify version bounds!, but less so with the rest. A complication is that stack.yaml is not visible from the web editor. Also, I'm not sure what happens when the snapshot is changed. I did this succesfully multiple times, but am not sure success is guaranteed.

…Maybe this file could be / is automatically generated (?), and the text could be shortened to

# Do not specify version bounds!
# The versions used in this exercise are listed here:  www.stackage.org/lts-18.14

[artamonovkirill]

Just something like

# Do not specify version bounds!
# Versions are derived from the Stackage snapshot.

should be OK, I think. If the version of Stackage would be there - even better, not required.

But this discussion is probably outside of the scope of this ticket - I'll close this one and create a new one for the disclamer.

[artamonovkirill]

Created #1098