svelte-d 0.2.0

svelte-d

Compile a bun(nodejs) svelte/svelte-kit into a tight wasm frontend and exe server based on D.

The browser cell is libwasm (LDC 1.43 try_table wasm-eh). The server cell is vibe.0. There is no Svelte-to-JS wrap and no second DOM or HTTP stack. One LDC 1.43+ builds the CLI, the wasm module, and the host exe. {#await} prints .await when the etcimon Binaryen fork asyncified the module; a rejected Promise is recorded and caught after rewind (libwasmAwaitFailed), never by wrapping the import in try/catch.

Getting Started

bun add github:etcimon/svelte-d
bunx svelte-d setup
bunx svelte-d drop-ws --force
bunx svelte-d compile --project .
bunx svelte-d build

Read more: LDC 1.43, forked wasm-opt, svelte-d.config.ts, debug vs release, code-d / VS Code, and the first .svelte file.

What you get

Debug keeps symbols (12.64 MiB wasm, 14.08 MiB host). bun run dev is debug. bun run build / svelte-d build is release + lflags -strip-all, then the fork wasm-opt asyncifies (so .await waits) and -Ozs. See sizes.

Use in a bun + SvelteKit project

bun add github:etcimon/svelte-d
bunx svelte-d setup          # LDC 1.43 + fork wasm-opt into ~/.svelte-d/toolchains and binaryen-build/

// svelte-d.config.ts  (project top-level)
export default { workspace: './svelte-engine-ws' }

import { dropWorkspace, compileWorkspace, workspaceDir } from 'svelte-d'

const ws = workspaceDir()
dropWorkspace({ dest: ws, force: true }) // overlay; never deletes dest
compileWorkspace({ ws, project: process.cwd() })

bunx svelte-d drop-ws --force
bunx svelte-d compile --project .
bunx svelte-d wasm --debug     # symbols for IR work
bunx svelte-d build            # IR + wasm/host release

drop-ws overlays the packaged svelte-engine template onto svelte-engine-ws and never rmdirs that folder. --force overwrites template-owned files only. A consumer machine does not need a riscv-dev tree: setup downloads LDC and the CI-built wasm-opt; DUB fetches libwasm / vibe-0 / openssl.

<script lang="d"> prints libwasm D. <script lang="ts"> splices into src-ts/modules jsExports. Do not mix those cells.

{#await job} is a JsPromise plus wireAwait in App.ready. On a fork-asyncified module that is job.await then libwasmAwaitFailed() (Svelte {:catch} visibility). Stock Binaryen 123/132 cannot --asyncify try_table; wireAwait then keeps .then / .error. Do not wrap .await in try/catch — throwBoundary stays a same-function landing pad off the import.

This repository

git clone --recurse-submodules https://github.com/etcimon/svelte-d.git
cd svelte-d
bunx svelte-d setup
bun install                    # prepare → pack engine + dub build → packages/svelte-d/bin/svelte-d
bunx svelte-d version          # prints 1
bun test
bun run docs                   # local Nextra site (empty basePath)

Submodules: svelte-engine (drop source) and binaryen (Flatten try_table fork, branch svelte-d). CI (.github/workflows/wasm-opt.yml) compiles that fork for Linux, macOS, and Windows and publishes the wasm-opt-svelte-d release. setup downloads the matching triple into binaryen-build/<os-arch>/ (Apache-2.0 LICENSE next to the binary) and ~/.svelte-d/toolchains/binaryen-svelte-d. Authors with CMake can still bun run build-wasm-opt. Official Binaryen 123/132 parse try_table and remain the fallback -Oz path.

How it compiles

Svelte / SvelteKit syntax falls through into an equivalent svelte-engine-ws tree (+page.svelte → src-d/ + src-svelte/; +page.server.* → webserver/source/). svelte-d prints libwasm / vibe.0 D IR. Kit features are accommodated in svelte-engine, libwasm, and vibe.0 — not by inventing a third runtime.

• svelte-d wasm --debug / svelte-d host / bun run dev — debug
• svelte-d wasm / svelte-d host --release / svelte-d build / bun run build — release

Docs: https://etcimon.github.io/svelte-d/. Language pages walk every interactive .svelte construct and the D IR it prints. Agent notes: AGENTS.md, architecture/.

License

MIT. LDC, libwasm, vibe.0, Svelte, Binaryen (binaryen-build/LICENSE), and Google asyncify.ts keep their own terms. See LICENSE.md.