Tooling

VS Code Extension

The vscode-seen/ directory contains the official VS Code extension. It tracks the shipped six-language set: en, ar, es, ru, zh, and ja.

Installation From Source

cd vscode-seen
npm install
npm run package
code --install-extension seen-*.vsix

Features

TextMate syntax highlighting for Seen syntax, comments, annotations, package imports, module aliases, facade component syntax, effects, hot reload helpers, and multilingual keywords.
LSP-backed diagnostics, completions, hover, definitions, references, rename, and document symbols through seen lsp.
Import-block folding for contiguous top-level import, use, and pub import declarations.
Build/check/run/package tasks using the shipped seen compile, seen check, seen run, and seen pkg commands.
Snippets for functions, classes, structs, enums, traits/interfaces, effects, packages, facade components, UI state/effects, shared modules, hot reload, GPU/SIMD, defer/errdefer, and FFI.

Commands

Command	Typical CLI
Seen: Build Project	`seen compile <file> [output]`
Seen: Run Project	`seen run <file>`
Seen: Check Project	`seen check <file>`
Seen: Compile Shared Module Objects	`seen compile ... --pic --object-manifest <path>`
Seen: Package Fetch	`seen pkg fetch`
Seen: Package Pack	`seen pkg pack`
Seen: Package Prebuild	`seen pkg prebuild`
Seen: Package Publish	`seen pkg publish`
Seen: Translate to Another Language	`seen translate <file> --from <lang> --to <lang>`

Extension-only commands such as update checks or visual helpers are editor UI features; compiler behavior remains controlled by the seen CLI.

Configuration

{
  "seen.compiler.path": "seen",
  "seen.lsp.enabled": true,
  "seen.lsp.trace.server": "off",
  "seen.formatting.enable": true,
  "seen.target.default": "native",
  "seen.compile.pic": false,
  "seen.compile.objectManifest": "",
  "seen.language.default": "en"
}

Language Server Protocol

Start the built-in language server:

seen lsp

The server resolves project language from nearby Seen.toml when possible and falls back to English. It masks /// ... /// block comments for source-symbol operations and supports completions/hover for packages, annotations, effects, capabilities, hot reload, imports, sealed classes, exports, new collection and memory types, and stdlib modules.

Neovim

require'lspconfig'.seen.setup{
  cmd = {"seen", "lsp"},
  filetypes = {"seen"},
  root_dir = require'lspconfig.util'.root_pattern("Seen.toml", ".git"),
}

Emacs

(lsp-register-client
 (make-lsp-client :new-connection (lsp-stdio-connection '("seen" "lsp"))
                  :major-modes '(seen-mode)
                  :server-id 'seen-lsp))

Diagnostics and Checks

Use the shipped checker for frontend/type diagnostics:

seen check src/main.seen

Use deterministic mode when auditing reproducibility-sensitive code:

seen check src/main.seen --profile deterministic

The checker and LSP surface warning diagnostics for conservative dead-code cases, including unreachable statements, unused locals or parameters, unused private top-level functions, and unused imports. Warning codes are reported as warnings in editor clients rather than promoted to errors.

Debugging Compiler Output

Useful environment-variable tracing:

SEEN_DEBUG_TYPES=1 seen compile program.seen program
SEEN_TRACE_LLVM=all seen compile program.seen program
SEEN_TRACE_LLVM=gep seen compile program.seen program

LLVM and compile-database emission are compile flags:

seen compile program.seen program --emit-llvm
seen compile program.seen program --emit-compile-db

Linux ARM64 Cross Sysroot

On pacman-compatible Linux hosts, create a local AArch64 cross sysroot without installing system packages globally:

./scripts/setup_linux_arm64_sysroot.sh
source artifacts/toolchains/linux-arm64/env.sh

The helper downloads and extracts cross-packages under artifacts/toolchains/linux-arm64/. The generated env.sh sets SEEN_LINUX_ARM64_SYSROOT and SEEN_LINUX_ARM64_GCC_TOOLCHAIN.

Validate the setup:

bash scripts/native_target_smoke.sh --compiler compiler_seen/target/seen --target linux-arm64
bash scripts/platform_matrix.sh --stage3 compiler_seen/target/seen --platform linux-arm64

Linux RISC-V Cross Sysroot and QEMU

Seen supports linux-riscv64 as an RV64GC Linux GNU userspace target. The canonical target list and triples are documented in Compilation Targets. On pacman-compatible Linux hosts, install system packages directly or create a local sysroot:

sudo pacman -Syu --needed clang llvm lld file qemu-user qemu-user-static qemu-system-riscv qemu-system-riscv-firmware riscv64-linux-gnu-binutils riscv64-linux-gnu-gcc riscv64-linux-gnu-glibc

# Optional local sysroot instead of relying on /usr/riscv64-linux-gnu:
./scripts/setup_linux_riscv64_sysroot.sh
source artifacts/toolchains/linux-riscv64/env.sh

Validate the fast emulator tier with QEMU user-mode:

bash scripts/test_riscv64_qemu.sh --compiler compiler_seen/target/seen --require
bash scripts/native_target_smoke.sh --compiler compiler_seen/target/seen --target linux-riscv64

For full guest validation, provide a RISC-V Linux kernel/rootfs with SSH and run:

SEEN_RISCV64_QEMU_KERNEL=/path/to/Image \
SEEN_RISCV64_QEMU_ROOTFS=/path/to/rootfs.qcow2 \
SEEN_RISCV64_QEMU_IDENTITY=/path/to/key \
bash scripts/test_riscv64_system_qemu.sh --compiler compiler_seen/target/seen --require

Import from C

Generate Seen bindings from a C header:

seen import-c mylib.h

The command outputs extern fun declarations that can be copied into Seen source or package interface modules.