proto

The proto module reads and writes the Protocol Buffers wire format. You supply a types map from field number to wire type; there’s no .proto schema compiler (that’s a separate concern), but it’s enough to talk to known endpoints. Import it with import proto.

For a self-describing binary format that doesn’t need type maps, see serialize (msgpack).

Functions

Function	Signature	Description
`encode`	`proto.encode(fields: object, types: object) → string`	Encode field-number → value pairs into wire bytes
`decode`	`proto.decode(bytes: string, types: object) → object`	Decode wire bytes into a field-number → value object

fields and types are keyed by the field number as a string ("1", "2", …).
Supported types: int32, int64, uint32, uint64, sint32, sint64 (zigzag), fixed32, fixed64, float, double, bool, string, bytes.
A field whose value is an array is encoded as a repeated field; on decode, repeated occurrences of a tag become an array.

import proto

let types = {"1": "int32", "2": "string", "3": "bool"}

let bytes = proto.encode({"1": 42, "2": "langoost", "3": true}, types)

let msg = proto.decode(bytes, types)
println(msg["2"])      // "langoost"

Schema-based (.proto)

For real .proto files, load the schema once and work with friendly field names instead of tag-to-type maps — no manual tag bookkeeping. This round-trips strings, ints, bools, and repeated fields.

Function	Signature	Description
`loadSchema`	`proto.loadSchema(path \| paths[]) → object`	Parse one or more `.proto` files into a schema object
`encodeMessage`	`proto.encodeMessage(schema, messageName: string, value: object) → string`	Encode a message by name
`decodeMessage`	`proto.decodeMessage(schema, messageName: string, bytes: string) → object`	Decode a message by name

import proto

let schema = proto.loadSchema("user.proto")

let bytes = proto.encodeMessage(schema, "User", {
    id: 42,
    name: "alice",
    roles: ["admin", "editor"],
})

let user = proto.decodeMessage(schema, "User", bytes)
println(user.name)     // "alice"

Standard library · View as Markdown · llms-full.txt