Codec

How log values become stored bytes and back. A payload is encoded in the binary format SchemaBinary.toCodec derives from its schema, makeForSchema, or as the UTF-8 bytes of its JSON, makeJsonForSchema, for a schema the binary format cannot lay out; either is a persistence contract: stored bytes must stay readable when dependencies change. An ordinary log stores its whole value through makeEntryCodec; a log whose entries carry a name or subject beside the payload, which storage indexes, gives Log.open an entry codec of its own.

Since v0.2.0

Constructors

makeEntryCodec

The entry codec of an ordinary log: the whole value is the payload, encoded with payload, makeForSchema(schema) unless given, and an entry has neither name nor subject. Decoding an entry that has either fails, so a log whose entries carry them is never misread through this codec.

Signature

declare const makeEntryCodec: <S extends Schema.Constraint>(schema: S, payload?: PayloadCodec<S>) => EntryCodec<S>

Source

Since v0.2.0

makeForSchema

The binary payload codec of payload, from SchemaBinary.toCodec, keeping the services the schema needs to encode and decode. Encoding returns a copy, so stored bytes never share the encoder’s buffer.

Signature

declare const makeForSchema: <S extends Schema.Constraint>(payload: S) => PayloadCodec<S>

Source

Since v0.2.0

makeJsonForSchema

Encodes one schema’s values as the UTF-8 bytes of their JSON, through Schema.toCodecJson: for a schema the binary format cannot lay out, such as a union whose members it cannot tell apart, as many of Effect AI’s are. Decoding checks the JSON against the schema.

Signature

declare const makeJsonForSchema: <S extends Schema.Constraint>(payload: S) => PayloadCodec<S>

Source

Since v0.2.0

Models

EntryCodec (interface)

How one log’s values map to the Store.Content storage keeps, and back, with the services its schema needs to encode and decode. Log.open takes one, and defaults to makeEntryCodec.

Signature

export interface EntryCodec<S extends Schema.Constraint> {
  readonly encode: (value: S["Type"]) => Effect.Effect<Store.Content, Schema.SchemaError, S["EncodingServices"]>
  readonly decode: (entry: Store.Content) => Effect.Effect<S["Type"], Schema.SchemaError, S["DecodingServices"]>
}

Source

Since v0.2.0

PayloadCodec (interface)

Encodes one schema’s values to bytes and decodes them back, in the binary format every log’s payloads share.

Signature

export interface PayloadCodec<S extends Schema.Constraint> {
  /** Produces an independently owned byte buffer for storage. */
  readonly encode: (
    payload: S["Type"]
  ) => Effect.Effect<Uint8Array<ArrayBuffer>, Schema.SchemaError, S["EncodingServices"]>
  /** Validates stored bytes and reconstructs the decoded value. */
  readonly decode: (bytes: Uint8Array) => Effect.Effect<S["Type"], Schema.SchemaError, S["DecodingServices"]>
}

Source

Since v0.2.0