Add `status` command to cabal #7500

fendor · 2021-08-01T18:19:36Z

Lightweight command that can query for very basic information
in a cabal project.
In particular, information about the compiler for the project and the
unit-id a given target belongs to.
Other flags are bound to follow.

A document that lays out the plan in more detail: https://gist.github.com/fendor/796b373aba26e12dbdecf7e40af78b32

This is the second part to #7489. It allows IDEs and hie-bios to quickly query for certain project meta information, in this case compiler information and what unit a target string belongs to.

Example:

> cabal status --output-format=json --compiler | jq
{
  "cabal-version": "3.7",
  "compiler": {
    "flavour": "ghc",
    "compiler-id": "ghc-8.10.7",
    "path": "/home/hugin/.ghcup/bin/ghc"
  }
}

> cabal status --output-format=json --compiler --target="lib:cabal" | jq
{
  "cabal-version": "3.7",
  "compiler": {
    "flavour": "ghc",
    "compiler-id": "ghc-8.10.7",
    "path": "/home/hugin/.ghcup/bin/ghc"
  },
  "targets": [
    {
      "target": "lib:cabal",
      "unit-id": "Cabal-3.7.0.0-inplace"
    }
  ]
}

Target strings that resolve to the same component are listed both times.

> cabal status --output-format=json --compiler --target="lib:cabal" --target="./Cabal/src/Distribution/Make.hs" | jq
{
  "cabal-version": "3.7",
  "compiler": {
    "flavour": "ghc",
    "compiler-id": "ghc-8.10.7",
    "path": "/home/hugin/.ghcup/bin/ghc"
  },
  "targets": [
    {
      "target": "lib:cabal",
      "unit-id": "Cabal-3.7.0.0-inplace"
    },
    {
      "target": "./Cabal/src/Distribution/Make.hs",
      "unit-id": "Cabal-3.7.0.0-inplace"
    }
  ]
}

Main advantage:

Very quick (only perform work you actually need)
Extensible
Composable

Disadvantage:

Maintain cabal command
Do we really need it?
Are we sure we are not just blindly adding commands without considering a bigger picture?

Alternatives:

Use cabal build --dry-run to generate plan.json and then parse that one.
- How to find the location of plan.json given a target string?
Merge this with another command
- E.g. Add option cabal build --dry-run --targets or something like that, but it feels like terrible UX.

Missing:

Old PR description, here for completeness

Lightweight command that can query for very basic information
in a cabal project.
In particular, you can list all targets in your project or print
information about the compiler. Other flags are bound to follow.

This is the second part to #7489. It allows IDEs and hie-bios to quickly query for certain project meta information, in this case compiler information and available targets.

Example:

> cabal ide --project-compiler
Resolving dependencies...
Compiler: ghc
Version: 8.10.2
Path: /home/hugin/.ghcup/bin/ghc-8.10.2

> cabal ide --targets
lib:Cabal
lib:cabal-testsuite
exe:setup
exe:cabal-tests
lib:cabal-install
exe:cabal
test:long-tests
test:integration-tests2
test:memory-usage-tests
test:unit-tests
lib:cabal-install-solver
test:unit-tests
lib:solver-benchmarks
exe:hackage-benchmark
test:unit-tests
lib:Cabal-QuickCheck
lib:Cabal-tree-diff
lib:Cabal-described
test:no-thunks-test
test:rpmvercmp
test:hackage-tests
test:custom-setup-tests
test:check-tests
test:parser-tests
test:unit-tests
test:cabal-benchmarks
lib:cabal-doctest

Main advantage:

Very quick (only perform work you actually need)
Extensible

Disadvantage:

Maintain cabal command
Do we really need it?
Are we sure we are not just blindly adding commands without considering a bigger picture?

Alternatives:

Use cabal build --dry-run to generate plan.json and then parse that one.
- How to find the location of plan.json?
Merge this with another command
- E.g. Add option cabal build --dry-run --targets or something like that, but it feels like terrible UX.

Missing:

~~[ ] Documentation~~
~~[ ] Test-cases~~

cabal-install/src/Distribution/Client/CmdIde.hs

michaelpj · 2021-08-02T11:38:06Z

If the intent is for these to be machine-readable, would it make sense to dump them out in JSON or similar by default?

phadej · 2021-08-02T12:05:11Z

If the intent is for these to be machine-readable, would it make sense to dump them out in JSON or similar by default?

What's wrong with reading plan.json then. cabal-plan library has SearchPlanJson and findPlanJson find the plan.json files.

fendor · 2021-08-02T14:17:56Z

What's wrong with reading plan.json then.

Personally, I think it is a bit troublesome to find plan.json reliably without user input. If we can mitigate that somehow, the ide command could also be just a frontend to query plan.json efficiently in a backwards compatible way.

Additionally, what is the simplest/efficient way to generate plan.json? cabal build all --dry-run? That takes on the cabal code-base 2.5s, while the ide command needs a couple of milliseconds.

However, I can see how appealing it would be to not have to introduce a new command...

jneira · 2021-08-02T14:34:40Z

This is the second part to #7489. It allows IDEs and hie-bios to quickly query for certain project meta information, in this case compiler information and available targets.

So it the replacement od cabal show-build-info? Afaiu it is complementary to cabal build --ddump-build-info=file, no? I mean all the info this command can offer will be in the show-build-info json, right? (and then the json requested by @michaelpj would be already covered)
In any case i like the design, the discoverability and it could be used for other tooling than ide's, like shell scripts

fendor · 2021-08-02T15:32:12Z

I mean all the info this command can offer will be in the show-build-info json, right?

Not only from build-info.json, e.g. available target information is from plan.json. Conceputally, all information we can query via cabal ide is available in plan.json and the component respective build-info.json.

So it the replacement od cabal show-build-info?

Basically yes, but intended to be a bit more general.

Afaiu it is complementary to cabal build --ddump-build-info=file, no?

Yep, ideally a quick way to query for project metadata, in this case project compiler and targets.

emilypi · 2021-08-11T21:38:23Z

@Mergifyio update

mergify · 2021-08-11T21:38:48Z

Command update: success

Branch has been successfully updated

gbaz · 2021-08-19T05:50:59Z

Some slight bikeshedding since we closed the old status pr in favor of this. I'd prefer the name be something like "status" (now available!) or "build-info" or the like, since I imagine end users and not just ides might want this.

Also I'd encourage taking a look at this status output from the old draft PR to see if all the information it provides is covered by this -- maybe the old work covers something missed/forgotten here? :-)

#2882 (comment)

emilypi · 2021-09-09T20:51:10Z

@fendor what do you think about @gbaz's comment?

fendor · 2021-09-16T14:52:29Z

I did not have time yet to revisit this PR.

jneira · 2021-10-08T10:30:14Z

@fendor ping, would be great to see this in 3.8 if possible

fendor · 2021-10-08T10:45:19Z

I think to get this over the finish line, we need the following resolved:

What is the scope?
- Pure query interface or is it allowed to perform side effects (such as writing a build-plan to plan.json)
Who is the intended consumer of this command?
- Should the output be human-readable or machine-readable?
  - hie-bios needs a quick way to query for the GHC version (in the current hie-bios interface, it actually needs the GHC path)
  - Humans might be interested in ide/info output too
What should be generally be queried via this interface?
- I proposed information available in plan.json and build-info.json if these files exist.

jneira · 2021-10-08T10:51:33Z

Thanks for the update

I think to get this over the finish line, we need the following resolved:
* What is the scope?
  
  * Pure query interface or is it allowed to perform side effects (such as writing a build-plan to `plan.json`)

I would say that it should generate the info if it is needed instead throw an error or show staled info.

* Who is the intended consumer of this command?
  
  * Should the output be human-readable or machine-readable?
    
    * hie-bios needs a quick way to query for the GHC version (in the current hie-bios interface, it actually needs the GHC path)
    * Humans might be interested in `ide`/`info` output too

I would say that human readable, as tools could access the undelying info (build-info and plan.json). that said it could have some flag to make it seudo machine readable.

* What should be generally be queried via this interface?
  
  * I proposed information available in `plan.json` and `build-info.json` if these files exist.

Sounds good

andreasabel · 2021-10-08T14:29:55Z

I agree with @gbaz that ide isn't the best name for a command that dumps some computed information. ide promises to crank up an IDE for package development or something grand like that.
Alt: values, show-info etc.

Lightweight command that can query for very basic information in a cabal project. In particular, information about the compiler for the project and the location of the so-called `build-info` field. Other flags are bound to follow.

This is more flexible than giving the user the build-info file directly, since this information is redundant as it is located in plan.json. There we can even express some more conditions. If the target is not a local dependency, the user can check that. If the user needs the build-info, then they can look it up in plan.json.

mergify · 2023-02-09T21:07:22Z

update

❌ Base branch update has failed

refusing to allow a GitHub App to create or update workflow .github/workflows/bootstrap.yml without workflows permission
err-code: 8016A

fendor · 2023-12-22T17:19:18Z

Closing as discussed in https://hackmd.io/mQjghm2zRgWgcyD4XKhBqA

A new PR will follow soonish, depending on the holidays.

fendor commented Aug 1, 2021

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fgaz added cabal-install: other type: enhancement labels Aug 3, 2021

fendor mentioned this pull request Aug 6, 2021

Implementation and purpose of Show-Build-Info #7489

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jneira mentioned this pull request Aug 18, 2021

Add a 'status' command. #3643

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This was referenced Aug 28, 2021

Add a command to list available build targets #4070

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Command to print GHC_PACKAGE_PATH #4806

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Add cabal packages #4493

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Provide a way to warn if the latest version of a package isn't selected #1751

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jneira linked an issue Aug 28, 2021 that may be closed by this pull request

Add a command to list available build targets #4070

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fendor force-pushed the feature/ide-command branch from 6504c2f to bcda142 Compare September 12, 2022 16:14

fendor mentioned this pull request Sep 16, 2022

Ambiguous target error haskell/hie-bios#370

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Don't output haddock stdout if verbosity is silent #7483

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fendor added 4 commits January 23, 2023 19:48

Add 'status' command to cabal

de17699

Lightweight command that can query for very basic information in a cabal project. In particular, information about the compiler for the project and the location of the so-called `build-info` field. Other flags are bound to follow.

Work in feedback regarding error handling

97af56b

Add tests for cabal status

0b89579

fendor force-pushed the feature/ide-command branch from 2ee5327 to 0995649 Compare January 23, 2023 18:49

WIP

c780f34

fendor force-pushed the feature/ide-command branch from 0995649 to c780f34 Compare January 23, 2023 18:53

This was referenced Jan 25, 2023

Add support for multi unit argument syntax haskell/haskell-language-server#3462

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RFC: Ide test integration haskellfoundation/tech-proposals#46

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ulysses4ever marked this pull request as draft February 7, 2023 03:05

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[Tooling] How to watch a cabal project #8853

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Add support for loading multiple components into one repl session #8726

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Improve performance of discovering the ghc version used by the project haskell/haskell-language-server#2010

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Redesign 'cabal path' command to account for projects #9583

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Add a cabal target command #9744

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Add `status` command to cabal #7500

Add `status` command to cabal #7500

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fendor commented Dec 22, 2023

Add status command to cabal #7500

Add status command to cabal #7500

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Add `status` command to cabal #7500

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