prisma-effect-kysely

Prisma generator producing Effect Schema types with Kysely-compatible column metadata, branded IDs, and intelligent UUID detection.

Install

bun add prisma-effect-kysely

Setup

generator effect_schemas {
  provider = "prisma-effect-kysely"
  output   = "./generated/effect"
}

npx prisma generate

Output

Three files: enums.ts, types.ts, index.ts.

import { Schema } from "effect";
import { columnType, generated, Selectable } from "prisma-effect-kysely";

// Branded ID
export const UserId = Schema.UUID.pipe(Schema.brand("UserId"));
export type UserId = typeof UserId.Type;

// Model schema
export const User = Schema.Struct({
  id: columnType(Schema.UUID, Schema.Never, Schema.Never),
  email: Schema.String,
  createdAt: generated(Schema.DateFromSelf),
});
export type User = typeof User;

// Kysely DB interface
export interface DB {
  User: Selectable<User>;
}

Consumer Usage

import { Selectable, Insertable, Updateable } from "prisma-effect-kysely";
import { User, UserId, DB } from "./generated";

function getUser(id: UserId): Promise<User> { ... }

type UserSelect = Selectable<typeof User>;
type UserInsert = Insertable<typeof User>;
type UserUpdate = Updateable<typeof User>;

const db = new Kysely<DB>({ ... });

Schema names are PascalCase regardless of Prisma model name (session_preference → SessionPreference).

Field Behavior

• @default / @updatedAt → generated() (omitted from insert, optional in update)
• @id with @default → columnType(type, Never, Never) (read-only)
• Optional fields → Schema.NullOr(type)
• Foreign keys → branded ID type from target model

Type Mappings

Prisma	Effect Schema
String	Schema.String
Int / Float	Schema.Number
BigInt	Schema.BigInt
Decimal	Schema.String
Boolean	Schema.Boolean
DateTime	Schema.DateFromSelf
Json	Schema.Unknown
Bytes	Schema.Uint8Array
Enum	Schema.Literal(...)
UUID	Schema.UUID

Arrays → Schema.Array(t). Nullable → Schema.NullOr(t).

UUID Detection

Priority order:

1. Native type: @db.Uuid
2. Documentation: @db.Uuid in field comment
3. Field name pattern: id, *_id, *_uuid, uuid

Custom Type Overrides

Use @customType in field docs to override Effect Schema:

model User {
  /// @customType(Schema.String.pipe(Schema.email()))
  email String @unique
  /// @customType(Schema.Number.pipe(Schema.positive()))
  age Int
}

Supported on all Prisma scalar types.

Implicit M2M Join Tables

Prisma columns A/B map to semantic snake_case fields via Schema.fromKey:

export const ProductToProductTag = Schema.Struct({
  product_id: Schema.propertySignature(
    columnType(Schema.UUID, Schema.Never, Schema.Never)
  ).pipe(Schema.fromKey("A")),
  product_tag_id: Schema.propertySignature(
    columnType(Schema.UUID, Schema.Never, Schema.Never)
  ).pipe(Schema.fromKey("B")),
});

Package Exports

Entry	Contents
prisma-effect-kysely	Type utilities + runtime helpers (default import)
prisma-effect-kysely/generator	Prisma generator binary entry
prisma-effect-kysely/kysely	getSchemas, columnType, generated, type utils
prisma-effect-kysely/error	NotFoundError, QueryError, QueryParseError, ...
prisma-effect-kysely/runtime	All runtime utilities

Development

bun install
bun run test
bun run typecheck
bun run build
bun run prepublishOnly  # lint + typecheck + test + build

Releasing

Uses Changesets.

bun changeset           # add changeset
git add .changeset/ && git commit -m "docs: changeset"
git push

CI opens a "Version Packages" PR. Merging it publishes to npm, tags, and creates a GitHub release. Requires NPM_TOKEN repo secret.

License

MIT