OCaml Changelog

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Read the latest releases and updates from the OCaml ecosystem.

We are pleased to announce the release of OCaml LSP 1.19.0. This version brings official support for OCaml 5.2. It also includes a new custom query to get

documentation and a fix regarding the handling of OCamlFormat processes.

See full changelog

Features

Fixes

  • Kill unnecessary OCamlFormat processes with sigterm rather than sigint or sigkill (ocaml/ocaml-lsp#1343)

We are pleased to announce the release of OCaml LSP 1.18.0. This version comes with a lot of fixes and new features.

Notable features that are included in this release are:

  • Improved hover behavior with less noisy hovers on some parse tree nodes such as keywords, comments, etc., along with support for hovering over PPX annotations and preview the generated code.
  • Some additional custom queries, particularly TypeEnclosing
  • Folding ifthenelse expressions
  • A new configuration option to control Dune diagnostics
  • Improved document symbols

...and many fixes to a handful of issues.

Feedback is very much welcomed on the the Discuss Announcement post and do not hesistate to report issues in the issue tracker.

See full changelog

Features

  • Introduce a configuration option to control Dune diagnostics. The option is called duneDiganostics, and it may be set to { enable: false } to disable diagnostics. (ocaml/ocaml-lsp#1221)

  • Support folding of ifthenelse expressions (ocaml/ocaml-lsp#1031)

  • Improve hover behavior (ocaml/ocaml-lsp#1245)

    Hovers are no longer displayed on useless parse tree nodes such as keywords, comments, etc.

    Multiline hovers are now filtered away.

    Display expanded PPXs in the hover window.

  • Improve document symbols (ocaml/ocaml-lsp#1247)

    Use the parse tree instead of the typed tree. This means that document symbols will work even if the source code doesn't type check.

    Include symbols at arbitrary depth.

    Differentiate functions / types / variants / etc.

    This now includes PPXs like let%expect_test or let%bench in the outline.

  • Introduce a destruct-line code action. This is an improved version of the old destruct code action. (ocaml/ocaml-lsp#1283)

  • Improve signature inference to only include types for elements that were absent from the signature. Previously, all signature items would always be inserted. (ocaml/ocaml-lsp#1289)

  • Add an update-signature code action to update the types of elements that were already present in the signature (ocaml/ocaml-lsp#1289)

  • Add custom ocamllsp/merlinCallCompatible request (ocaml/ocaml-lsp#1265)

  • Add custom ocamllsp/typeEnclosing request (ocaml/ocaml-lsp#1304)

Fixes

  • Detect document kind by looking at Merlin's suffixes config.

    This enables more LSP features for non-.ml/.mli files. Though it still depends on Merlin's support. (ocaml/ocaml-lsp#1237)

  • Correctly accept the --clientProcessId flag. (ocaml/ocaml-lsp#1242)

  • Disable automatic completion and signature help inside comments (ocaml/ocaml-lsp#1246)

  • Includes a new optional/configurable option to toggle syntax documentation. If toggled on, allows display of syntax documentation on hover tooltips. Can be controlled via environment variables and by GUI for VS code. (ocaml/ocaml-lsp#1218)

  • For completions on labels that the LSP gets from Merlin, take into account whether the prefix being completed starts with ~ or ?. Change the label completions that start with ? to start with ~ when the prefix being completed starts with ~. (ocaml/ocaml-lsp#1277)

  • Fix document syncing (ocaml/ocaml-lsp#1278, ocaml/ocaml-lsp#1280, fixes ocaml/ocaml-lsp#1207)

  • Stop generating inlay hints on generated code (ocaml/ocaml-lsp#1290)

  • Fix parenthesising of function types in SignatureHelp (ocaml/ocaml-lsp#1296)

  • Fix syntax documentation rendering (ocaml/ocaml-lsp#1318)

We are pleased to announce the release of OCaml LSP 1.17.0. This version comes packed with fixes and new features.

Notable features that come in this release include:

  • Compatibility with Odoc 2.3.0: This version is fully compatible with Odoc 2.3.0, introducing support for the latest syntax features like tables and "codeblock output."
  • New Actions for Code Cleanup: You can now mark or remove unused elements such as 'open', types, for loop indexes, modules, match cases, 'rec', and constructors, making your code cleaner and more efficient.
  • Auto-completion for 'in' Keyword: To address the long standing issue of the in keyword completing to other terms in the editor, we've added auto-completion for this keyword in OCaml LSP. Typing in will now only suggest auto completion for the in keyword.
See full changelog

Fixes

  • Fix missing super & subscripts in markdown documentation. (#1170)
  • Do not invoke dune at all if --fallback-read-dot-merlin flag is on. (#1173)
  • Fix semantic highlighting of infix operators that contain '.'. (#1186)
  • Disable highlighting unit as an enum member to fix comment highlighting bug. (#1185)
  • Improve type-on-hover and type-annotate efficiency by only formatting the type of the first enclosing. (#1191, #1196)
  • Fix the encoding of URI's to match how vscode does it (#1197)
  • Fix parsing of completion prefixes (#1181)

Features

  • Compatibility with Odoc 2.3.0, with support for the introduced syntax: tables, and "codeblock output" (#1184)
  • Display text of references in doc strings (#1166)
  • Add mark/remove unused actions for open, types, for loop indexes, modules, match cases, rec, and constructors (#1141)
  • Offer auto-completion for the keyword in (#1217)

We've released OCaml LSP 1.16.2 with a fix that was introduced in 1.16.1 that prevented users from using preprocessor such as CPPO.

See full changelog

Fixes

  • Fix file permissions used when specifying output files of pp and ppx. (ocaml-lsp#1153)

We're thrilled to announce the release of OCaml LSP 1.16.1! 🎉

This release comes with new "Extract local" and "Extract function" code actions to easily refactor your code.

We've also disabled code lenses by default following user feedback. You can follow the discussion on GitHub.

This release is also the first OCaml LSP release to use upstream Merlin. Among other things, this means that it is compatible with all the OCaml versions supported by Merlin: currently OCaml 4.14 and 5.0.0.

We're also releasing numerous bug fixes, including:

  • A fix to the integration with Dune RPC on Windows, which, alongside Dune 3.9.0, makes OCaml LSP report Dune errors to the editors with Dune watch mode enabled.
  • Minor improvements to the Odoc <-> Markdown conversion to return better function documentation on the editor.

And much more! Read the full changelog for a complete list of improvements and bug fixes.

See full changelog

Features

  • Add "Remove type annotation" code action. (#1039)
  • Support settings through didChangeConfiguration notification (#1103)
  • Add "Extract local" and "Extract function" code actions. (#870)
  • Depend directly on merlin-lib 4.9 (#1070)

Fixes

  • Support building with OCaml 5.0 and 5.1 (#1150)

  • Disable code lens by default. The support can be re-enabled by explicitly setting it in the configuration. (#1134)

  • Fix initilization of ocamlformat-rpc in some edge cases when ocamlformat is initialized concurrently (#1132)

  • Kill unnecessary $ dune ocaml-merlin with SIGTERM rather than SIGKILL (#1124)

  • Refactor comment parsing to use odoc-parser and cmarkit instead of octavius and omd (#1088)

    This allows users who migrated to omd 2.X to install ocaml-lsp-server in the same opam switch.

    We also slightly improved markdown generation support and fixed a couple in the generation of inline heading and module types.

  • Allow opening documents that were already open. This is a workaround for neovim's lsp client (#1067)

  • Disable type annotation for functions (#1054)

  • Respect codeActionLiteralSupport capability (#1046)

  • Fix a document syncing issue when utf-16 is the position encoding (#1004)

  • Disable "Type-annotate" action for code that is already annotated. (#1037, fixes #1036)

  • Fix semantic highlighting of long identifiers when using preprocessors (#1049, fixes #1034)

  • Fix the type of DocumentSelector in cram document registration (#1068)

  • Accept the --clientProcessId command line argument. (#1074)

  • Accept --port as a synonym for --socket. (#1075)

  • Fix connecting to dune rpc on Windows. (#1080)

On behalf of the ocaml-lsp team, I’m pleased to announce ocaml-lsp-server versions 1.15.0-4.14 and 1.15.0-5.0 for OCaml 4.14 and 5.0, respectively. This is the first time we release ocaml-lsp supporting two compiler versions. We look forward to your feedback.

See full changelog

Features

  • Enable semantic highlighting support by default (#933)

  • Support connecting over pipes and socket. Pipes on Windows aren't yet supported (#946)

    More about communication channels in LSP specification.

  • Re-enable ocamlformat-rpc for formatting code snippets (but not files and not on Windows) (#920, #939)

    One needs to have installed either ocamlformat package version > 0.21.0 or, otherwise, ocamlformat-rpc package. Note that previously ocamlformat-rpc came in a standalone OPAM package, but since ocamlformat version > 0.21.0, it comes within ocamlformat package.

  • Add custom ocamllsp/hoverExtended request (#561)

  • Support utf-8 position encoding clients (#919)

    More about position encoding in LSP specification.

  • Show unwrapped module alias types on hovering over module names. This is due to upgrading to merlin 4.7 and using merlin's verbosity=smart by default (#942)

Fixes

  • Respect the client's completion item resolve and preSelect capabilities (#925, #936)

  • Disable polling for dune's watch mode on Windows and OCaml 4.14.0 (#935)

  • Fix semantic highlighting of "long identifiers," e.g., Foo.Bar.x (#932)

  • Fix syncing of document contents:

    • For ranges that span an entire line (#927)
    • Previously, whole line edits would incorrectly eat the newline characters (#971)
See full changelog

Fixes

  • Fix random requests failing after switching documents (#904, fixes #898)

  • Do not offer related diagnostic information unless the user enables in client capabilities (#905)

  • Do not offer diagnostic tags unless the client supports them (#909)

  • Do not attach extra data to diagnostics unless the client supports this (#910)

  • Use /bin/sh instead of /bin/bash. This fixes ocamllsp on NixOS

See full changelog

Fixes

  • Fix various server crashes when opening non OCaml/Reason files. Files such as dune, cram, etc. would cause the server to crash. (#884, fixes #871)

  • Ignore unknown tags in merlin configuration to improve forward compatibility with Dune. (#883)

On behalf of the ocamllsp team, I'm pleased to announce version 1.14.0. This release contains a new code action to help you inline definitions thanks to @jfeser. We look forward to your feedback.

See full changelog

Features

  • Code action for inlining let bindings within a module or expression. (#847)

  • Tag "unused code" and "deprecated" warnings, allowing clients to better display them. (#848)

  • Refresh merlin configuration after every dune build in watch mode (#853)

Fixes

  • Respect showDocument capabilities. Do not offer commands or code actions that rely on this request without client support. (#836)

  • Fix signatureHelp on .mll files: avoid "Document.dune" exceptions

See full changelog
  • Allow cancellation of workspace symbols requests (#777)

  • Fix unintentionally interleaved jsonrpc IO that would corrupt the session (#786)

  • Ignore SIGPIPE . (#788)

See full changelog

Fixes

  • Fix a bad interaction between inferred interfaces and promotion code actions in watch mode (#753)

  • Fix URI parsing (#739 fixes #471 and #459)

See full changelog

Fixes

  • Fix preprocessing, ppx, and reason support (#735 fixes #696, #706)

  • Support include in folding ranges (#730)

See full changelog

Features

  • Fix cancellation mechanism for all requests (#707)

  • Allow cancellation of formatting requests (#707)

  • Add --fallback-read-dot-merlin to the LSP Server (#705). If ocamllsp is started with this new flag, it will fall back to looking for Merlin configuration in .merlin files rather than calling dune ocaml-merlin. (#705)

  • Support folding more ranges (#692)

See full changelog
  • Fix process termination. Once the lsp server is stepped, the process will gracefully terminate (#697, fixes #694)

  • Forward stderr from dune's merlin configuration to the lsp server's stderr (#697)

See full changelog
  • Fix bug with large buffers being resized incorrectly in Lev

  • Add folding ranges for more AST types (#680)

On behalf of the ocamllsp team, I’m excited to announce the availability of version 1.11.0. This release is an important milestone for the project because it introduces integration with our favorite build system. When you run dune in watch mode, you will now be able to see build errors in the diagnostics panel of your editor. It’s all rather experimental for now, so your feedback and bug reports are appreciated.

As usual, the full change log is below.

Happy hacking.

See full changelog

Features

  • Add support for dune in watch mode. The lsp server will now display build errors in the diagnostics and offer promotion code actions.

  • Re-introduce ocamlformat-rpc (#599, fixes #495)

Fixes

  • Fix workspace symbols that could have a wrong path in some cases (#675)

On behalf of the ocamllsp team, I’m pleased to announce version 1.10.0. The only new feature this release offers is better code folding, but there are some important bug fixes and performance improvements. If you encounter any sluggishness with our server, do not hesitate to report it.

Unless there are serious bugs with this release, this will be the last release for OCaml 4.13.

Happy Hacking.

See full changelog

Features

  • Add better support for code folding: more folds and more precise folds

Fixes

  • Fix infer interface code action crash when implementation source does not exist (#597)

  • Improve error message when the reason plugin for merlin is absent (#608)

  • Fix chdir races when running ppx (#550)

  • More accurate completion kinds. New completion kinds for variants and fields. Removed inaccurate completion kinds for constructors and types. (#510)

  • Fix handling request cancellation (#616)

See full changelog

Fixes

  • Ppx processes are now executed correctly (#513)

Breaking Change

  • ocamllsp drops support for .merlin files, and as a consequence no longer depends on dot-merlin-reader. (#523)

Features

  • New code action to automatically remove values, types, opens (#502)
See full changelog
  • Fix debouncing of document updates. It was essentially completely broken in all but the most trivial cases. (#509 fixes #504)

  • Fix completion when passing named and functional arguments (#512)

On behalf of the ocaml-lsp team, I’m pleased to announce version 1.8.0. This release contains some quality of life bug fixes, better diagnostics locations, and a few new code actions. Happy hacking.

See full changelog

Features

  • Add a new code action Add missing rec keyword, which is available when adding a rec keyword can fix Unbound value ... error, e.g.,

    let fact n = if n = 0 then 1 else n * fact (n - 1)
                                      (* ^^^^ Unbound value fact *)
    

    Adding rec to the definition of fact will fix the problem. The new code action offers adding rec.

  • Use ocamlformat to properly format type snippets. This feature requires the ocamlformat-rpc opam package to be installed. (#386)

  • Add completion support for polymorphic variants, when it is possible to pin down the precise type. Examples (<|> stands for the cursor) when completion will work (#473)

    Function application:

    let foo (a: [`Alpha | `Beta]) = ()
    
    foo `A<|>
    

    Type explicitly shown:

    let a : [`Alpha | `Beta] = `B<|>
    

    Note: this is actually a bug fix, since we were ignoring the backtick when constructing the prefix for completion.

  • Parse merlin errors (best effort) into a more structured form. This allows reporting all locations as "related information" (#475)

  • Add support for Merlin Construct command as completion suggestions, i.e., show complex expressions that could complete the typed hole. (#472)

  • Add a code action Construct an expression that is shown when the cursor is at the end of the typed hole, i.e., _|, where | is the cursor. The code action simply triggers the client (currently only VS Code is supported) to show completion suggestions. (#472)

  • Change the formatting-on-save error notification to a warning notification (#472)

  • Code action to qualify ("put module name in identifiers") and unqualify ("remove module name from identifiers") module names in identifiers (#399)

    Starting from:

    open Unix
    
    let times = Unix.times ()
    let f x = x.Unix.tms_stime, x.Unix.tms_utime
    

    Calling "remove module name from identifiers" with the cursor on the open statement will produce:

    open Unix
    
    let times = times ()
    let f x = x.tms_stime, x.tms_utime
    

    Calling "put module name in identifiers" will restore:

    open Unix
    
    let times = Unix.times ()
    let f x = x.Unix.tms_stime, x.Unix.tms_utime
    

Fixes

  • Handle workspace change notifications. Previously, the server would only use the set of workspaces given at startup to search for workspace symbols. After this change, workspace folders that are added later will also be considered. (#498)

  • Do not show "random" documentation on hover

  • Correctly rename a variable used as a named/optional argument (#478)

  • When reporting an error at the beginning of the file, use the first line not the second (#489)

See full changelog

Features

  • Add sub-errors as "related" information in diagnostics (#457)

  • Add support for navigating to a symbol inside a workspace (#398)

  • Show typed holes as errors

    Merlin has a concept of "typed holes" that are syntactically represented as _. Files that incorporate typed holes are not considered valid OCaml, but Merlin and OCaml-LSP support them. One example when such typed holes can occur is when on "destructs" a value, e.g., destructing (Some 1) will generate code match Some 1 with Some _ -> _ | None -> _. While the first underscore is a valid "match-all"/wildcard pattern, the rest of underscores are typed holes.

See full changelog

Fixes

  • Switch verbosity from 1 to 0. This is the same default that merlin uses. The old value for verbosity (#433)

  • Get fresh diagnostics (warning and error messages) on a file save (#438)

    Note: If you want the fresh diagnostics to take into account changes in other files, you likely need to rebuild your project. An easy way to get automatic rebuilds is to run dune in a watching mode, e.g.,[dune build --watch].

On behalf of the ocaml-lsp team, I'd like to announce version 1.6.0 of ocaml-lsp-server. The highlight of this release is the updated version of merlin which brings lots of new bug fixes.

See full changelog

Features

  • Code action to annotate a value with its type (#397)

Fixes

  • Fix interface/implementation switching on Windows (#427)

  • Correctly parse project paths with spaces and other special characters that must be escaped.

  • Print types with -short-paths even if the project wasn't built yet

See full changelog
  • Support 4.12 and drop support for all earlier versions

  • Update to the latest version of merlin

See full changelog

Fixes

  • Backport fixes from merlin (#382, #383)

  • Encode request & notification params in a list. This is required by the spec. (#351)

On behalf of the ocaml-lsp team, it is my pleasure to announce version 1.4.0. This release introduces support for automatic signature help. Signature help is not yet present in all possible contexts. We intend to improve to support as many relevant language constructs as possible in the future. Many thanks to @mnxn for implementing this feature.

The full change log is replicated at the end of this post for your convenience.

Happy Holidays!

See full changelog

Features

  • Support cancellation notifications when possible. (#323)

  • Implement signature help request for functions (#324)

  • Server LSP requests & notifications concurrently. Requests that require merlin are still serialized. (#330)

On behalf of the ocaml-lsp team, I’d like to announce version 1.3.0.

This release an improvement in keyword completion and a new code action. Keywords are now filtered by the context the user requested the completion, and there’s a new code action to quickly populate .mli files with the the inferred types from the .ml file.

See full changelog

Features

  • Code action to insert inferred module interface (#308)

  • Filter keywords by context (#307)

On behalf of the ocaml-lsp team, I’d like to announce version 1.2.0.

This version contains many bug fixes and some performance improvements A couple of interesting features made it in as well:

  • Auto-completion of OCaml keywords (not available for reason)
  • The ability to jump to the declaration of a value in the .mli.
See full changelog

Features

  • Add keyword completion

  • Add go to declaration functionality to jump to a value's specification in a .mli file (#294)

Fixes

  • #245: correctly use mutexes on OpenBSD (#264)

  • #268: Do not use vendored libraries when building the lsp package (#260)

  • #271: Clear diagnostics when files are closed

  • Disable non-prefix completion. There's no reliably way to trigger it and it can be slow.

If you want to contribute to a new release announcement, check out the Contributing Guide on GitHub.