daml-zed

Daml support for the Zed editor.

What you get

Syntax highlighting from a Daml-specific tree-sitter grammar, plus everything damlc multi-ide provides: completion, type on hover, diagnostics, go to definition, rename, and cross-package jump-to-definition in multi-package projects.

The outline (cmd-shift-o) lists templates, choices, interfaces, interface instances and exceptions, which is how a Daml file is usually navigated.

Failing scripts

Turn on autorun_scripts and every Daml Script is evaluated when you open the file, so a failure becomes an ordinary red squiggle on the declaration:

Script execution failed on commit at Test:24:12:
  Attempt to fetch or exercise a contract not visible to the reading parties.
  Contract: #0:0 (Main:Asset@37a33fb2…)
  actAs: 'Bob'
  Disclosed to: 'Alice'

Committed transactions:
  TX 0 1970-01-01T00:00:00Z (Test:18:14)
  #0:0
  └─> 'Alice' creates Main:Asset@37a33fb2… with issuer = 'Alice'; …

The reason, the transactions committed before the failure and the disclosure are all in the diagnostic. No sidecar involved. It is off by default because it costs a full evaluation of every script in the file each time it is opened.

Script results

Script results answer a different question from the one above: not did it pass but what did it actually do. A passing script produces a transaction tree and a table of who ends up seeing which contract, and neither dpm test nor a diagnostic shows you that. If you only need pass or fail, autorun_scripts is enough and you can skip the rest of this section.

They render in an editor pane rather than a webview.

Invoke the Show script results code action on a Daml Script. The result is written to .daml/ide/script-results.md; open that file once, split beside your source, and it updates on every click and on every edit. Zed's markdown: open preview renders the contract tables.

# Script: setup

`test/daml/Test.daml`

## Transactions

    TX 0 1970-01-01T00:00:00Z (Test:18:14)
    #0:0
    │   consumed by: #1:0
    └─> 'Alice' creates Main:Asset@37a33fb2…
                with
                  issuer = 'Alice'; owner = 'Alice'; name = "TV"

## Contracts

| id   | status   | issuer  | owner   | name | Alice | Bob |
|------|----------|---------|---------|------|-------|-----|
| #2:1 | active   | 'Alice' | 'Alice' | "TV" | S     | W   |

This runs outside the editor because it has to. In VS Code the extension opens a webview and subscribes to a daml:// virtual resource; a Zed extension runs in WebAssembly, so it can neither register the client-side command the lens refers to nor open a panel, and Zed's LSP client does not advertise window/showDocument. So a sidecar, daml-ide-bridge, proxies the language server and writes the pane.

The bridge is optional. Without it everything else still works and only script results are missing. Build and install it with:

cargo install --path crates/daml-ide-bridge

Set script_results to false to run the language server directly even when a bridge is on PATH.

Requirements

Daml SDK 3.4 or newer with dpm on your PATH. Install it with:

curl https://get.digitalasset.com/install/install.sh | sh

The extension runs dpm damlc multi-ide. multi-ide is always used: it can only be turned off with the legacy Daml Assistant, which this extension does not target.

Installation

Until the extension is in the Zed registry, install it from a checkout:

git clone https://github.com/herata/daml-zed

Then in Zed: cmd-shift-p → zed: install dev extension → pick daml-zed/editors/zed.

Building a dev extension needs rustup, a Rust of 1.82 or newer as the default toolchain, and the wasm32-wasip2 target. Zed installs the target itself, but only into the default toolchain — a directory override does not apply, and an older default fails with no prebuilt artifacts available for target 'wasm32-wasip2'.

rustup default stable
rustup target add wasm32-wasip2

Settings

{
  "lsp": {
    "daml-language-server": {
      "settings": {
        "log_level": "Warning",
        "extra_arguments": ["--ghc-option", "-Wall"]
      }
    }
  }
}

Setting	Values	Default	Meaning
log_level	Debug, Info, Warning, Error	Warning	Passed to damlc multi-ide as --log-level
extra_arguments	list of strings	[]	Appended to the damlc multi-ide command line
autorun_scripts	bool	false	Evaluate every script on open, so failures appear as diagnostics
script_results	bool	true	Run the language server behind daml-ide-bridge when one is available
bridge_path	string	unset	Where to find daml-ide-bridge, if not on PATH
bridge_args	list of strings	[]	Passed to the bridge, e.g. ["--log", "/tmp/bridge.log"]

If dpm is not on your PATH, or you need the legacy daml assistant or an SDK older than 3.4, point the extension at a binary directly. This bypasses everything above, so pass the arguments yourself:

{
  "lsp": {
    "daml-language-server": {
      "binary": {
        "path": "/Users/me/.dpm/bin/dpm",
        "arguments": ["damlc", "multi-ide", "--telemetry-ignored"]
      }
    }
  }
}

Telemetry

The extension always passes --telemetry-ignored, so the language server sends nothing. The VS Code extension asks for consent through a dialog; a Zed extension has no way to show one, and sending telemetry without asking is not an option, so it is simply off.

Repository layout

Path	What it is
editors/zed/	The Zed extension, compiled to wasm32-wasip2
editors/zed/src/server.rs	Argument construction and dpm lookup. No Zed API calls, so it is unit tested
editors/zed/src/lib.rs	The only code that talks to Zed. Not automatically testable
editors/zed/languages/daml/	tree-sitter queries
editors/zed/testdata/sample.daml	Exercises every Daml construct; CI checks it parses and that every query compiles against it
crates/daml-ide-bridge/	The script-results sidecar: an LSP proxy that writes the pane

The grammar lives in a separate repository, tree-sitter-daml, because it is a fork of tree-sitter-haskell and needs to keep merging from upstream. extension.toml pins the revision.

Development

cd editors/zed
cargo test                          # the pure logic in server.rs
cargo build --target wasm32-wasip2  # what Zed loads
cargo fmt --check && cargo clippy --all-targets -- -D warnings

The WebAssembly half cannot be tested automatically. After changing it, install the dev extension and walk this list against testdata/sample.daml:

• The file is recognised as Daml
• template, with, where, signatory, choice, controller, interface, viewtype, exception, try, catch are keyword-coloured
• Template, interface and exception names are type-coloured; choice names are constructor-coloured
• cmd-shift-o lists the templates, their choices, the interface, the interface instance and the exception
• Breaking a type produces a diagnostic, and fixing it clears it
• Hover shows a type
• Go to definition reaches the standard library
• Completion renders as name : Type
• cmd-/ comments with --
• In a multi-package project, go to definition crosses package boundaries
• With autorun_scripts on, breaking a Script - make a party exercise a choice it does not control - produces an error diagnostic on the script's declaration whose message includes the committed transactions
• debug: open language server logs shows the bridge in front of dpm damlc multi-ide --telemetry-ignored --log-level=Warning, or just the latter if no bridge is installed
• With the bridge installed, the "Show script results" code action on a Script writes .daml/ide/script-results.md, and Zed shows a notification with the path
• With that file open, editing the script updates it without any manual reload, and clicking a different script switches the pane

License

Apache-2.0.