HLS Plugin to provide Alternate Literal Formats.

[drsooch]

The following PR is for issue #1560. Currently all functionality is "complete", however there is a lot of dead code (code that exists but the plugin doesn't need to use). I am looking to get some feedback on the plugin itself, and hopefully through the feedback most of the dead code can be culled.

General Mechanics:

A new rule CollectLiterals traverses the GHC source tree to look for literals (Literals.hs). The rule returns the exhaustive list of literals and also a list of FormatType. FormatType's are derived from currently active extensions as well as a base set that are valid no matter the extensions active.

When a user invokes a codeAction keybind, the alternateNumberFormat handler will filter out only the literals that are in the current range of the invoked codeAction. In the handler, the logic for generating possible alternatives is done, and each possibility is transformed into a codeAction sent to the user.

Most of the alternate formats are provided by the Numeric package (show* functions).

Potential Issues:

• Literals.hs traverses nearly the entire source tree just to make sure all of the Literals are captured. Certain types of literals end up being discarded (Literals with no source text attached or source location). When codeActions are generated we just immediately throw those out. As a result the Literal constructors of IntPrimLiteral and FracPrimLiteral aren't actually used.
• Similarly, in Conversion.hs we transform the Extensions NumericUnderscores and NegativeLiterals (LexicalNegation in GHC > 9), into NoFormat which essentially means we don't care about them right now. I'm not sure if generating cases for this would be useful or needed. (NegativeLiterals may not actually be useful to this plugin)
• The NumDecimals extension allows for literals such as 1.23e5 to be used places where Integer's are expected. I could've gone ahead and defaulted to using the Numeric package, but I tried to encode some logic to display different possible exponents. Ex. 12.3e4, 123.0e3, and 1.23e5 for 123000.
• I believe all of the necessary code changes for files such as cabal.project and haskell-language-server.cabal but please let me know if there is more to do.
• I didn't attach any bounds to the plugins cabal file as I was using Stack to build and I am not quite clear on how to generate these bounds effectively.
• There is (presumably) no compatibility with other GHC versions other than the one I used (8.10.7). I'm not sure how to go about fixing those issues (other than just building with each possible GHC).
• I have no idea why my Test setup is not working. I modeled the testing functionality after explicit imports plugin, but for whatever reason, the test server does not find ANY codeActions let alone just alternateNumberFormat plugins.

Let me know what you think.

[fendor]

Suggested change

	-- Generate up to 3 possible choices where:
	-- dropWhile (\d -> val `div` d) > 1000) implies we want at MOST 3 digits to left of decimal
	-- | Generate up to 3 possible choices where:
	-- dropWhile (\d -> val `div` d) > 1000) implies we want at MOST 3 digits to left of decimal

[fendor]

This way it is haddock compliant and on hover you actually see the comment.

Additionally, check for valid Haddock syntax so it renders properly.

[fendor]

Awesome, this is a great plugin! I have some general comments and ideas but feel free to disagree.

Traversing the whole AST for each change might be very expensive, so we should see whether we can optimise that somehow.

I've looked into your testsuite issue, but can't tell right now what the issue is.

[jneira]

Many thanks for working on this! It looks great overall

• I didn't attach any bounds to the plugins cabal file as I was using Stack to build and I am not quite clear on how to generate these bounds effectively.

A usual way is use cabal gen-bounds but we are not being too strict with bounds in other plugins so i would follow what other plugins are doing to get consistenncy between them, take a look to:

haskell-language-server/plugins/hls-splice-plugin/hls-splice-plugin.cabal

Lines 32 to 50 in ab46fe8

	build-depends:
	, aeson
	, base >=4.12 && <5
	, containers
	, dlist
	, extra
	, foldl
	, ghc
	, ghc-exactprint
	, ghcide >=1.2 && <1.5
	, hls-plugin-api >=1.1 && <1.3
	, lens
	, lsp
	, retrie
	, syb
	, text
	, transformers
	, unliftio-core
	, unordered-containers

It has bounds on base, ghcide and hls-plugin-api and nothing more

• There is (presumably) no compatibility with other GHC versions other than the one I used (8.10.7). I'm not sure how to go about fixing those issues (other than just building with each possible GHC).

If you have the chance of building your version for other ghc versions (f.e 8.6.5, 8.8.4 and 9.0.1) it would be great. But We have the ci covering all supported versions so you can leverage it. I would add a line like

haskell-language-server/.github/workflows/test.yml

Lines 187 to 189 in ab46fe8

	- if: matrix.test
	name: Test hls-splice-plugin
	run: cabal test hls-splice-plugin --test-options="-j1 --rerun-update" || cabal test hls-splice-plugin --test-options="-j1 --rerun" || LSP_TEST_LOG_COLOR=0 LSP_TEST_LOG_MESSAGES=true LSP_TEST_LOG_STDERR=true cabal test hls-splice-plugin --test-options="-j1 --rerun"

• I have no idea why my Test setup is not working. I modeled the testing functionality after explicit imports plugin, but for whatever reason, the test server does not find ANY codeActions let alone just alternateNumberFormat plugins.

Well, a good way to trace test problems is enable full log output of lsp messages, take a look to the test suite linked just above and use the same invocation locally (the relevant part is LSP_TEST_LOG_COLOR=0 LSP_TEST_LOG_MESSAGES=true LSP_TEST_LOG_STDERR=true)

[drsooch]

• I have no idea why my Test setup is not working. I modeled the testing functionality after explicit imports plugin, but for whatever reason, the test server does not find ANY codeActions let alone just alternateNumberFormat plugins.

Well, a good way to trace test problems is enable full log output of lsp messages, take a look to the test suite linked just above and use the same invocation locally (the relevant part is LSP_TEST_LOG_COLOR=0 LSP_TEST_LOG_MESSAGES=true LSP_TEST_LOG_STDERR=true)

I ran the tests with logs enabled. Looks like an exception occurs (which I think is relevant?) and then a shutdown message is sent to the server.

It looks like it's attempting to do some actual work but for whatever reason a shutdown message is sent?

[jneira]

@drsooch i have taken the liberty of add the plugin to the rest of cabal.project's (for ghc 9.0.1 and 9.2.1) and to the test workflow, to see how is going in ci

[jneira]

I ran the tests with logs enabled. Looks like an exception occurs (which I think is relevant?) and then a shutdown message is sent to the server.

That message about finishing the build is normal. I guess the test is not finding the code action, not sure why

Take a look to this test in the haddock plugin:

haskell-language-server/plugins/hls-haddock-comments-plugin/test/Main.hs

Line 41 in 1eb133f

actions <- getCodeActions doc (Range (Position l c) (Position l $ succ c))

It is looking for a code action in a specific code range, maybe you need something similar to trigger it?

[jneira]

Hi, it seems the plugin is not buildable with ghc-8.6.5, a version we still support. I hope only changing plugin base constraints could make the build work:

Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: ghcide-1.4.2.4 (user goal)
[__1] trying: base-4.12.0.0/installed-4.12.0.0 (dependency of ghcide)
[__2] next goal: hls-alternate-number-format-plugin (user goal)
[__2] rejecting: hls-alternate-number-format-plugin-0.1.0.0 (conflict:
base==4.12.0.0/installed-4.12.0.0, hls-alternate-number-format-plugin =>
base>=4.13 && <5)
[__2] fail (backjumping, conflict set: base,
hls-alternate-number-format-plugin)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: base, ghcide,
hls-alternate-number-format-plugin

https://github.com/haskell/haskell-language-server/runs/4209830202?check_suite_focus=true

[drsooch]

Hi, it seems the plugin is not buildable with ghc-8.6.5, a version we still support. I hope only changing plugin base constraints could make the build work:

Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: ghcide-1.4.2.4 (user goal)
[__1] trying: base-4.12.0.0/installed-4.12.0.0 (dependency of ghcide)
[__2] next goal: hls-alternate-number-format-plugin (user goal)
[__2] rejecting: hls-alternate-number-format-plugin-0.1.0.0 (conflict:
base==4.12.0.0/installed-4.12.0.0, hls-alternate-number-format-plugin =>
base>=4.13 && <5)
[__2] fail (backjumping, conflict set: base,
hls-alternate-number-format-plugin)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: base, ghcide,
hls-alternate-number-format-plugin

https://github.com/haskell/haskell-language-server/runs/4209830202?check_suite_focus=true

Yeah, I started testing out 9.0.1 as well, and there are some changes needed However, those are pending @fendor's comments about using syb. I will aim to clean up the builds for each GHC version tonight.

[Ailrun]

Minor nitpicking here

[jneira]

test data files in .cabal are needed to merge this
also, could you add the plugin to the features docs page, with a demo if possible? that will make it more relevant and discoverable
thanks!

[drsooch]

test data files in .cabal are needed to merge this also, could you add the plugin to the features docs page, with a demo if possible? that will make it more relevant and discoverable thanks!

What about hackage.yml? Does that need updating?

[jneira]

test data files in .cabal are needed to merge this also, could you add the plugin to the features docs page, with a demo if possible? that will make it more relevant and discoverable thanks!

What about hackage.yml? Does that need updating?

oh, you are damn right, thanks for noting it
could you add it yourself, please?

[jneira]

There is a failing test plugin related for ubuntu and 8.10.7:

   Conversions
    Match NumDecimal:        FAIL
      *** Failed! Falsified (after 21 tests):
      10
      Use --quickcheck-replay=414296 to reproduce.
      Use -p '/Match NumDecimal/' to rerun this test only.

[jneira]

test data files in .cabal are needed to merge this also, could you add the plugin to the features docs page, with a demo if possible? that will make it more relevant and discoverable thanks!

What about hackage.yml? Does that need updating?

oh, you are damn right, thanks for noting it could you add it yourself, please?

done with eb05482

[jneira]

the plugin looks great, many thanks for working on this
only left fix the failing test

[jneira]

/rerun-workflow Testing