WCL — Wil's Configuration Language

A configuration language being rebuilt from scratch on the rewrite branch. The previous implementation lives on main; this branch starts over with a smaller, faster core. Expect the language surface to change while it stabilises.

Status

Currently supports HCL-like fields and blocks:

name = "alpha"
count = 3
enabled = true

service "web" {
  port = 8080
  metadata {
    region = "us-east-1"
  }
}

Scaffolding a project

wcl init generates a new project folder from a template. A template is a WCL document declaring property questions plus the file / folder blocks to create; WCL ships a few built-ins.

wcl init --list                      # list built-in templates
wcl init minimal ./my-project        # prompts for each property
wcl init minimal ./app -D name=app --defaults   # non-interactive
wcl init minimal ./app --answers answers.json   # answers from a file (.wcl or .json)

Built-in templates: minimal (a single commented main.wcl), plus three multi-folder wdoc projects — page (website), book (sidebar TOC), and presentation (slide deck). The multi-folder ones lay out main.wcl with schema/, data/, and wdoc/ folders, and project custom data into one generated page per entry:

wcl init page ./my-site -D name="My Site" --defaults
wcl wdoc build ./my-site/main.wcl --out ./my-site/_site

<template> may also be a path to your own template .wcl file, or the name of a user template installed under $XDG_DATA_HOME/wcl/templates/<name>/ (default ~/.local/share/wcl/templates/<name>/) as a folder containing a template.wcl — these show up in wcl init --list too. Inside a template, a file's contents pull in answers with the answer("name") builtin (in an interpolating heredoc):

import <scaffold.wcl>

property "name" {
  prompt  = "Project name"
  default = "my-project"
}

file "main.wcl" {
  content = $<<WCL
// ${answer("name")}
WCL
}

Browser editor

wcl editor serves a browser IDE for the current directory: a gitignore-aware file tree, tabbed CodeMirror editing of any text file, WCL language support (completion, hover, diagnostics from the built-in language server), and a live preview pane that renders the wdoc page you are editing — unsaved changes included — from the project's root document (an explicit argument, else ./main.wcl).

cd my-site && wcl editor          # then open the printed URL

Layout

• crates/wcl_lang — parser and AST library (wcl_lang::parse, wcl_lang::parse_file)
• crates/wcl — wcl CLI binary (wcl parse, wcl check)
• editor-ui/ — the wcl editor web frontend (SolidJS + Forge), embedded into the binary at build time
• examples/ — sample input files

Development

just workspace-build      # cargo build --workspace
just workspace-test       # cargo test --workspace
just workspace-lint       # clippy with -D warnings
just workspace-bench      # criterion benchmarks
just cli-run -- check examples/basic.wcl

Building the wcl crate builds the editor frontend when it is stale, which needs pnpm on PATH (editor-ui/). Without node/pnpm, set WCL_EDITOR_UI_SKIP=1 to embed a placeholder page instead — everything else works normally.

Editor + install:

just cli-install          # cargo install --path crates/wcl --locked
just vscode-build         # npm install + tsc compile (editors/vscode)
just vscode-package       # produce a .vsix via @vscode/vsce
just vscode-install       # install the .vsix into VS Code via `code --install-extension`

Run just --list to see every recipe grouped by purpose.

License

WCL is licensed under the MIT License. Copyright (c) 2026 Wil Taylor.