#MoonBit sqlc WASM Plugin

#Description

#Key Features

#Type-Safe Codegen

• Result[T, DBError] for all query and decode paths
• Compile-time SQL/type validation via sqlc
• AST → Pretty Printer pipeline (no string concatenation)

#Minimal Runtime

• DB, Transaction, Row, RowIter, Value, MockDB
• Published as Mairzzcllo/moonbit_sqlc_plugin/runtime on mooncakes 0.1.8
• Target wasm-gc — no native driver required in generated code

#Plugin-Host Separation

• WASM plugin handles codegen only
• WASI stdin/stdout protobuf I/O (inline WAT FFI, no external shim)
• Dual-file output: types.mbt + queries.mbt

#Quick Start

#A. App Developers — mooncakes.io

#Add runtime to an existing project

moon update
moon add Mairzzcllo/moonbit_sqlc_plugin@0.1.8
moon check --target wasm-gc

{
  "deps": {
    "Mairzzcllo/moonbit_sqlc_plugin": "0.1.8"
  }
}

import {
  "Mairzzcllo/moonbit_sqlc_plugin/runtime" @runtime,
}

moon check --target wasm-gc
moon test --target wasm-gc

moon add pulls from mooncakes.io and does not require login. Only moon publish needs credentials.

#Minimal new project (from scratch)

mkdir myapp && cd myapp

{
  "name": "your_org/myapp",
  "version": "0.1.0",
  "preferred-target": "wasm-gc",
  "supported-targets": "+wasm+wasm-gc"
}

import {
  "Mairzzcllo/moonbit_sqlc_plugin/runtime" @runtime,
}

moon update
moon add Mairzzcllo/moonbit_sqlc_plugin@0.1.8
# copy types.mbt + queries.mbt here
moon check --target wasm-gc

#Upgrade / remove

moon add Mairzzcllo/moonbit_sqlc_plugin@0.1.8   # upgrade
moon remove Mairzzcllo/moonbit_sqlc_plugin       # remove

.\scripts\setup-mooncakes.ps1 -Version 0.1.8

bash scripts/setup-mooncakes.sh --version 0.1.8

#B. Plugin Developers — Build WASM & Generate Code

#Requirements

#Clone Repository

git clone https://github.com/Mairzzcllo/MoonBit-sqlc-WASM-plugin.git
cd MoonBit-sqlc-WASM-plugin
moon check
moon test

#Build WASM Plugin

moon build --target wasm --release

#Run Example

#Linux / macOS

chmod +x scripts/run-example.sh scripts/setup-mooncakes.sh
bash scripts/run-example.sh
bash scripts/run-example.sh --full --release --skip-build

#Windows (PowerShell)

.\scripts\run-example.ps1
.\scripts\run-example.ps1 -Full -Release -SkipBuild
$OutputEncoding = [Console]::OutputEncoding = [Text.Encoding]::UTF8

#Configure sqlc.yaml and Generate

version: "2"
plugins:
  - name: moonbit
    wasm:
      url: file://./_build/wasm/release/build/plugin/plugin.wasm
      sha256: ""
sql:
  - engine: postgresql
    schema: schema.sql
    queries: query.sql
    codegen:
      - out: gen
        plugin: moonbit
        options:
          package_name: myapp

sqlc generate

Note: Do not commit platform-specific sha256 hashes. Use scripts/sync-sqlc-sha256.ps1 after building locally.

#Usage Example

fn example(db: @runtime.DB) {
  match query_get_user(db, 42L) {
    Ok(user) => println(user.name)
    Err(@runtime.DBError::NoRows) => println("not found")
    Err(e) => println("error: \{e}")
  }
}

#Plugin Options

#Troubleshooting

#Project Structure

plugin/           # WASM plugin (codegen + WASI I/O)
runtime/          # Generated-code runtime (published on mooncakes)
examples/users/   # Reproducible example
tests/            # golden + integration tests
docs/             # API reference and quickstart
scripts/          # run-example / setup-mooncakes / sync-sqlc-sha256

#Tests

moon check --deny-warn
moon test --deny-warn          # 937 inline tests
moon build --target wasm --release

tests/integration/wasm/validate_plugin.ps1 -TestSqlc -Release -SkipBuild
tests/integration/e2e/run_e2e.ps1 -SkipBuild -Release

#Architecture

sqlc (protobuf) → wasi_io → codec → adapter → ir
  → type_codegen / query_codegen → ast → emitter → types.mbt + queries.mbt

#Docs and Links

#LICENSE

Third-party notices are in NOTICE. WASM I/O protocol reference: sqlc-gen-greeter (MIT).