Editor setup

Strand's editor support is a language server and a tree-sitter grammar. Both live outside the shell, so they cost strand nothing. The repository ships no editor plugin or editor configuration; this page gives the settings that start them in Helix and Neovim.

The language server

The language server is strand-dev lsp. Build strand-dev from the checkout and put it on your PATH:

cargo build --release -p strand-dev
cp target/release/strand-dev ~/.local/bin/

strand-dev lsp speaks the Language Server Protocol over standard input and output. An editor starts it for files ending in .strand.

What it does

Diagnostics: what strand check finds in the config's files (all of it but a missing strand-auth helper), for every file of the config: when a file opens or is saved, and 200 ms after you stop typing.
Completion after $, . and <->, and of element, component, keyword, prop and event names and enum values.
Hover: a name's type, and its documentation from the schemas.
Go to definition, across the config's files.
Rename across files: a state, a let, a component, a token, and a component's prop at its call sites. A rename that would break the config, or one of a built-in name, is refused.
Code actions: the "did you mean" fixes the diagnostics carry, a missing key, and "extract component", which moves the selected subtree into a new component.
Formatting, with the formatter strand fmt uses.

It checks a file together with the rest of its config: the config directory, when the file is part of it; else an editor workspace folder that holds .strand files and the file; else the file's own directory. That is the rule strand check <file> uses, with the workspace folder added. Changes made to the files outside the editor are seen too.

Two initialization options change its defaults: debounceMs (how long after typing it waits, default 200) and configDir (the config directory, default the one strand check uses).

Helix

Add this to ~/.config/helix/languages.toml:

use-grammars = { only = ["strand"] }

[language-server.strand]
command = "strand-dev"
args = ["lsp"]

[[language]]
name = "strand"
scope = "source.strand"
file-types = ["strand"]
comment-token = "//"
indent = { tab-width = 2, unit = "  " }
language-servers = ["strand"]

[[grammar]]
name = "strand"
source = { path = "/path/to/strand/crates/strand-dev/tree-sitter-strand" }

use-grammars keeps the build step below to this one grammar; leave it out if you build other grammars yourself. Set path to your checkout. Then build the grammar and copy the highlight query:

mkdir -p ~/.config/helix/runtime/grammars ~/.config/helix/runtime/queries/strand
hx --grammar build
cp /path/to/strand/crates/strand-dev/tree-sitter-strand/queries/highlights.scm \
  ~/.config/helix/runtime/queries/strand/
hx --health strand

On Arch Linux the program is called helix, not hx.

The queries use nvim-treesitter's capture names. Helix reads them, but a capture its themes name differently is not coloured: Helix themes call numbers constant.numeric, for one, where the query says number.

Neovim

Neovim 0.11 and later configure language servers with vim.lsp.config. In ~/.config/nvim/init.lua:

vim.filetype.add({ extension = { strand = "strand" } })

vim.lsp.config("strand", {
  cmd = { "strand-dev", "lsp" },
  filetypes = { "strand" },
})
vim.lsp.enable("strand")

For highlighting, compile the grammar into Neovim's parser directory and copy its queries:

cd /path/to/strand/crates/strand-dev/tree-sitter-strand
mkdir -p ~/.local/share/nvim/site/parser ~/.local/share/nvim/site/queries/strand
cc -shared -fPIC -O2 -I src src/parser.c src/scanner.c \
  -o ~/.local/share/nvim/site/parser/strand.so
cp queries/*.scm ~/.local/share/nvim/site/queries/strand/

and start it for .strand buffers:

vim.api.nvim_create_autocmd("FileType", {
  pattern = "strand",
  callback = function() vim.treesitter.start() end,
})

VS Code and other editors

There is no VS Code extension for Strand. VS Code starts a language server only through an extension, and the repository has none, nor a TextMate grammar for its highlighting. Any editor whose language client can run a command over standard input and output for *.strand files can use strand-dev lsp as it is.

The tree-sitter grammar

The grammar is in crates/strand-dev/tree-sitter-strand: grammar.js, the parser generated from it (src/parser.c, beside a hand-written src/scanner.c), and four queries in queries/:

highlights.scm, the highlighting;
indents.scm, one indent level inside every block and bracketed list;
injections.scm, which injects only into comments (as the comment language), since strings hold no other language;
locals.scm, the scopes, definitions and references.

All four use nvim-treesitter's capture names. The grammar follows docs/grammar.md, and its generated files are tree-sitter 0.27.0's.

Editor setup

#The language server

#What it does

#Helix

#Neovim

#VS Code and other editors

#The tree-sitter grammar