MoonBit · ORM & SQL toolkit

The seam between your type and its table.

Types are contracts. The seam that stitches a MoonBit struct into SQL is the query — and moonorm sews it at compile time. A field that cannot map is not a runtime surprise; it is a compile error, caught on this very line.

struct User → users

MoonBit — type side relation — SQL side

id: Int64 idBIGINTprimary key

name: String nameTEXTnot null

email: String emailTEXTnot null unique

okall fields mapped, 0 errors

CREATE TABLE PostgreSQL

CREATE TABLE users (id BIGSERIAL PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL UNIQUE)

Hover a field to lock its mapping. Click email to watch a type mismatch break the seam. Every type and every statement on the right is produced by this library, compiled to JavaScript.

The narrative

Four movements along one seam

01 — map

A struct becomes a table

Declare a model once; moonorm derives the DDL for SQLite, PostgreSQL and MySQL. The mapping is checked as you type — a field whose type has no column analogue is a compile error, not a migration surprise.

02 — compile

A query becomes SQL

A MoonBit query expression unfolds through the seam into a dialect's SQL. where_, join, group_by each emit their fragment; values are bound, never interpolated.

03 — evolve

A schema diff becomes a plan

Reflect a model against a live database, diff the two, and generate up/down migrations. Each change is labelled reversible or not, and checked against the type side.

04 — land

A session becomes work

Unit-of-work, identity map, dirty tracking and savepoints ride on the same seam. Write MoonBit; the transaction commits SQL.

The contract ledger

MoonBit type ↔ SQL type

The strong type and the weak type, reconciled. Rows that cannot map are marked — and explained.

MoonBit	SQLite	PostgreSQL	MySQL	nullable
Int	INTEGER	INTEGER	INT	·
Int64	INTEGER	BIGINT	BIGINT	·
Double	REAL	DOUBLE PRECISION	DOUBLE	·
String	TEXT	TEXT	TEXT	·
Bool	INTEGER	BOOLEAN	TINYINT(1)	·
Bytes	BLOB	BYTEA	BLOB	·
Int ↔ TEXT	needs an explicit `kind=`; the seam will not guess			no

Side by side

What you write, what runs

MoonBit

let q = User::model()
  .select()
  .where_(fn(u) { u.name == "ada" })
  .order_by("id", Asc)
  .limit(10)
let (sql, params) = q.build()
// params: [Text("ada"), Int(10)]

SQL · dialect-neutral

SELECT id, name, email
  FROM users
 WHERE name = ?
 ORDER BY id ASC
 LIMIT ?

Placeholders are dialect tokens chosen by the driver (SQLite/MySQL ?, PostgreSQL $1). Values are bound out-of-band — injection is absent by construction.

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