mclsp 0.5.0

McCode DSL language server (LSP) for .instr and .comp files

mclsp — McCode DSL Language Server

A Language Server Protocol implementation for the McCode domain-specific languages: McStas (.instr, .comp) and McXtrace (.instr, .comp).

Built on top of mccode-antlr and pygls.

Features

Feature	Status
Syntax error diagnostics	✅
Keyword completion	✅
Component name completion	✅
Parameter completion inside Component(…)	✅
Hover: component signature & description	✅
Syntax highlighting (TextMate grammar)	✅
Go-to-definition of .comp files	✅

Installation

pip install mclsp
# or
conda install -c conda-forge mclsp

Requires mccode-antlr >= 0.18.2 and a McCode installation (McStas or McXtrace) for component library lookup.

Editor setup

VS Code

Install the McCode extension from the Marketplace (it bundles mclsp), or point the generic LSP client extension at mclsp --stdio.

A minimal extension stub is provided in vscode-extension/.

Neovim (nvim-lspconfig)

require('lspconfig').mclsp.setup {}

A config will be submitted upstream to nvim-lspconfig once the server stabilises.

Helix

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

[[language]]
name = "mccode"
scope = "source.mccode"
file-types = ["instr", "comp"]
language-servers = ["mclsp"]

[language-server.mclsp]
command = "mclsp"
args = ["--stdio"]

Running the server manually

mclsp --stdio          # communicate over stdin/stdout (standard LSP mode)
mclsp --tcp 2087       # listen on TCP port 2087 (useful for debugging)

Development

git clone https://github.com/mcdotstar/mccode-language-server.git mclsp
cd mclsp
uv sync
uv run pytest