Bincaml-based LSP by katrinafyi · Pull Request #116 · agle/bincaml

katrinafyi · 2026-04-09T06:52:39Z

This is a basic LSP which has:

go to definition of block/global/parameter variables, blocks, procedures, ADT cases, and declared type names.
hover information of the above terms,
autocompletion of the above terms,
symbol tree view,
procedure DOT graph generation,
syntax error highlighting from lexer / parser,
loading error highlighting (e.g., due to undefined variable errors),
debug highlight mode where every token is highlighted,
an attempt at a cached on-demand dependency system for internal LSP state.

You will need to configure the LSP in your editor for the appropriate file type. In Astronvim, it's something like

    config = {
      basillsp = {
        cmd={"/home/rina/progs/obasil/_build/default/lsp/bin/main.exe"}, filetypes={"basilir"}, root_dir = require("lspconfig.util").root_pattern("."),},

    },

inside the ~/.config/nvim/lua/plugins/astrolsp.lua file.

The DOT graph generation and highlighting mode is accessed using LSP code actions. In Astronvim, it's <Space>la.

Screenshots

Hover information

Symbol outline

Error and token highlighting

Code actions

https://www.github.com/BNFC/bnfc/pull/475 but still broken

Conflicts: dune-project lib/fe/AbsBasilIR.ml lib/fe/BNFC_Util.ml lib/fe/BasilIR.cf lib/fe/LexBasilIR.mll lib/fe/ParBasilIR.mly lib/fe/PrintBasilIR.ml lib/fe/ShowBasilIR.ml lib/fe/SkelBasilIR.ml lib/fe/TestBasilIR.ml tree-sitter/.gitattributes tree-sitter/.gitignore tree-sitter/grammar.js tree-sitter/queries/highlights.scm tree-sitter/tree-sitter.json

JTrenerry · 2026-04-10T00:34:57Z

+                  let open Lwt.Syntax in
+                  let* () =
+                    run_command ~notify_back
+                      (Filename.quote_command "dot"


so lsp requires dot?

Yeah, but only for the generate graph code action.

ok, xdg-open is pre cool, did not know about it

yeah, won't work on macos tho ;-;

Macos should have "open" https://github.com/b0-system/b0/blob/63c4db467ab3ad34c8e8744269915947436c5601/src/std/b0_web_browser.ml#L48

Conflicts: tree-sitter/grammar.js

bincaml_lsp unconditionally depends on ppx_expect

JTrenerry · 2026-04-14T03:48:37Z

flake doesn't have some of the packages needed, although my nix is dying right now so unsure if skill issue

agle · 2026-04-14T05:28:35Z

Go to definition of globals goes to declaration rather than last definition

Conflicts: dune-project nix/bincaml.nix nix/shell.nix test/cram/roundtrip.t

agle

There's nothing really objectionable here, its very tightly coupled to the concrete ast from bincaml which might produce some maintenence churn but we'll see. needs some docs

agle · 2026-04-14T07:39:05Z

+
+let proc_lspsymbol_at_pos ~lspsymbols lsppos =
+  lspsymbols
+  |> List.find_opt (fun (sym : symbol) ->


Performance improvement available by using Map.split

Yeah it's true but this only iterates through toplevel declarations so I'm gonna leave it for now. There's other O(n) work happening anyway.

agle · 2026-04-14T07:44:39Z

+              in
+              let range = Option.value ~default:default_range range in
+              [ Lsp.Types.Diagnostic.create ~message ~range ~severity:Error () ]
+        in


Mentioned previously but including here:

do we want to use algebraic effects to pass errors through

effect Warning of string * Lexing.pos * filename (*display and continue *) effect Alarm of string * Lexing.pos * filename (* display and continue *) exception Error (*give up*)

is there a way to do this with a Logs reporter that includes a lexing position tag and displays the output as lines

It would be cool. I think Logs integration is somewhat easier if we don't need to dynamically choose between continuing or aborting. We can do this later.

agle · 2026-04-14T07:47:49Z

+          |> Iter.flat_map (function StmtWithAttrib1 (stmt, _) -> of_stmt stmt))
+    |> Iter.map (fun ((range, name), context) ->
+        ((range, name), Field, context @ ("within block" :: bcontext)))
+  in


In general I think i would prefer a solution that embeds the neccessary information in bincaml ir with the minimal amount of bookeeping e.g. the token under cursor map. We still have work to do to properly support everything and its inherently lossy so its something to work towards in the future. loadir.ml is a mess and needs some substantial work to make it cleaner and separate its various concerns (esp. type inference, processing concrete ast, and ir building)

agle

(docs changes required from previous review)

Conflicts: test/cram/malloc_free.t

katrinafyi · 2026-04-17T06:59:17Z

Go to definition of globals goes to declaration rather than last definition

With this, did you mean like a reassignment to $mem? Is there an example?

agle · 2026-04-17T07:04:50Z

Any register assignment where the register is a global will go to the declaration in global scope rather than the previous assignment. Not sure if LSP ui has support for multiple and it requires a control flow analysis so maybe ignore.

katrinafyi · 2026-04-17T07:15:47Z

Yeah that's expected atm but it would be really useful. I can definitely look into it after this PR.

katrinafyi

comments should be fixed now.

katrinafyi · 2026-04-17T07:53:09Z

+
+let proc_lspsymbol_at_pos ~lspsymbols lsppos =
+  lspsymbols
+  |> List.find_opt (fun (sym : symbol) ->


Yeah it's true but this only iterates through toplevel declarations so I'm gonna leave it for now. There's other O(n) work happening anyway.

katrinafyi · 2026-04-17T07:55:32Z

+              in
+              let range = Option.value ~default:default_range range in
+              [ Lsp.Types.Diagnostic.create ~message ~range ~severity:Error () ]
+        in


It would be cool. I think Logs integration is somewhat easier if we don't need to dynamically choose between continuing or aborting. We can do this later.

katrinafyi · 2026-04-17T07:55:50Z

+          |> Iter.flat_map (function StmtWithAttrib1 (stmt, _) -> of_stmt stmt))
+    |> Iter.map (fun ((range, name), context) ->
+        ((range, name), Field, context @ ("within block" :: bcontext)))
+  in


katrinafyi · 2026-04-17T08:03:21Z

Has anyone seen this before?

Promoting                              
  _build/default/bincaml-lsp/lib/ocaml/5.4.1/site-lib/bincaml_lsp/.formatted/bincaml_lsp.ml
  to bincaml-lsp/lib/ocaml/5.4.1/site-lib/bincaml_lsp/bincaml_lsp.ml.
Error: failed to promote               
bincaml-lsp/lib/ocaml/5.4.1/site-lib/bincaml_lsp/bincaml_lsp.ml
Permission denied

ohh this happens when you have a nix build . output in the current folder.

agle · 2026-04-23T04:23:24Z

-  (qcheck-stm :with-test))
+  qcheck-core
+  qcheck-alcotest
+  qcheck-stm)


Is this intentional?

katrinafyi added 30 commits February 18, 2026 14:16

initial import of basls (badly broken)

fc5c1aa

restarting lol

0302f09

token lexing

71971b2

url

e4cbc37

add logs

5c7b116

tree-sitter init

9dcaa93

generate.py

acc1dea

queries

188cf5b

add src

d6af481

disable

f9d28b5

update highlights.. it's really slow...

7d17b30

blah

ff42b3b

grammar generated by

7e4ce9c

https://www.github.com/BNFC/bnfc/pull/475 but still broken

new grammar after fork

fa58458

ListAttrKeyValue

44d58bb

try inline

f5b353e

it works???

8dc5fa9

fix cf

b23c10e

remove stuff

7f8a549

update grammar

5303c93

highlights

e932265

onhighlight code action

bb23da1

tough

b3ccf23

update w new tokens

5d6086f

lwt_react..........

9f37d4e

send_diagnostic as trace

47b261f

continuing past errors ;-;

16d8217

lsp_logs

8e1761e

duneproject

d608bf2

JTrenerry reviewed Apr 10, 2026

View reviewed changes

katrinafyi added 2 commits April 10, 2026 16:36

Merge remote-tracking branch 'origin/main' into lsp

295b00b

Conflicts: tree-sitter/grammar.js

remove lsp llibrary

3b73fdf

katrinafyi force-pushed the lsp branch 2 times, most recently from 04707ff to 3b73fdf Compare April 10, 2026 08:57

katrinafyi added 4 commits April 10, 2026 19:20

fix tests and revert il files

9cc9143

fmt???

0b19e32

opam fmt

c500b9f

fix opam lint..? idk why qcheck cannot be with-test, or why

848b646

bincaml_lsp unconditionally depends on ppx_expect

katrinafyi added 4 commits April 14, 2026 15:29

bincaml_lsp package in nix

aaa42d1

add bincaml_lsp package and add to dev shell

d963b54

Merge remote-tracking branch 'origin/main' into lsp

028f660

Conflicts: dune-project nix/bincaml.nix nix/shell.nix test/cram/roundtrip.t

revert accidental test changes

d427462

agle reviewed Apr 14, 2026

View reviewed changes

agle requested changes Apr 16, 2026

View reviewed changes

katrinafyi added 2 commits April 17, 2026 16:42

Merge remote-tracking branch 'origin/main' into lsp

1061ff9

Conflicts: test/cram/malloc_free.t

fix changes

ac1f02d

some review comments

a4facb6

add warning when code actions misused

5f024c8

katrinafyi added 2 commits April 17, 2026 17:19

move record_backtrace

df989d1

touch up comments and docs

25d3a85

katrinafyi commented Apr 17, 2026

View reviewed changes

promote and add .ocamlformat-ignore ;-;;;;;;;

271fed5

agle reviewed Apr 23, 2026

View reviewed changes

Comment thread dune-project

(qcheck-stm :with-test))

qcheck-core

qcheck-alcotest

qcheck-stm)

Copy link
Copy Markdown

Owner

agle Apr 23, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Is this intentional?

Conversation

katrinafyi commented Apr 9, 2026

Screenshots

Hover information

Symbol outline

Error and token highlighting

Code actions

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

JTrenerry commented Apr 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

agle commented Apr 14, 2026

Uh oh!

agle left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

agle left a comment

Choose a reason for hiding this comment

Uh oh!

katrinafyi commented Apr 17, 2026

Uh oh!

agle commented Apr 17, 2026

Uh oh!

katrinafyi commented Apr 17, 2026

Uh oh!

katrinafyi left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

katrinafyi commented Apr 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

JTrenerry commented Apr 14, 2026 •

edited

Loading

katrinafyi commented Apr 17, 2026 •

edited

Loading