protobuf

Kind	kit
Categories	data-format serialization encoding
Keywords	protobuf protocol-buffers serialization grpc binary

Protocol Buffers binary serialization for Kit

Files

File	Description
`kit.toml`	Package manifest with metadata and dependencies
`src/protobuf.kit`	Wire format encoding, decoding, and field value helpers
`tests/protobuf.test.kit`	Module import verification tests
`examples/basic.kit`	Encoding, decoding, and inspecting messages
`examples/nested.kit`	Embedded messages and multi-level nesting
`examples/person.kit`	Complete Person schema with phones and enums
`examples/repeated.kit`	Packed and non-packed repeated fields
`LICENSE`	MIT license file

Dependencies

No Kit package dependencies.

Installation

kit add gitlab.com/kit-lang/packages/kit-protobuf.git

Usage

import Kit.Protobuf

License

MIT License - see LICENSE for details.

Exported Functions & Types

`ProtobufError`

Protobuf error type with specific variants for different failure modes.

Variants

ProtobufEncodeError {message}

ProtobufDecodeError {message}

`WireType`

Protocol buffer wire types (encoding format identifiers).

Variants

Varint

Variable-length integer encoding (int32, int64, uint32, uint64, sint32, sint64, bool, enum)

Fixed64

64-bit little-endian encoding (fixed64, sfixed64, double)

LengthDelim

Length-prefixed data (string, bytes, embedded messages, packed repeated)

StartGroup

Deprecated group start marker (not supported)

EndGroup

Deprecated group end marker (not supported)

Fixed32

32-bit little-endian encoding (fixed32, sfixed32, float)

`FieldValue`

Field value variants for different protobuf types.

Variants

VarintValue {Int}

Variable-length integer value

Fixed32Value {Int}

32-bit fixed-width value

Fixed64Value {Int}

64-bit fixed-width value

BytesValue {List, Int}

Raw byte sequence

StringValue {String}

UTF-8 string value

MessageValue {List, Field}

Nested message (list of fields)

RepeatedValue {List, FieldValue}

Non-packed repeated field

PackedValue {List, Int}

Packed repeated integers

`IntDecodeResult`

Internal result types for decoding with remaining bytes.

Variants

IntDecodeOk {IntWithRest}

IntDecodeErr {String}

`FieldType`

Field type descriptors for schema definitions.

Variants

TInt32

Signed 32-bit integer

TInt64

Signed 64-bit integer

TUint32

Unsigned 32-bit integer

TUint64

Unsigned 64-bit integer

TSint32

ZigZag-encoded signed 32-bit integer

TSint64

ZigZag-encoded signed 64-bit integer

TBool

Boolean value (encoded as varint 0/1)

TEnum

Enumeration value (encoded as varint)

TFixed32

32-bit fixed-width integer

TSfixed32

Signed 32-bit fixed-width integer

TFloat

32-bit floating point (encoded as fixed32)

TFixed64

64-bit fixed-width integer

TSfixed64

Signed 64-bit fixed-width integer

TDouble

64-bit floating point (encoded as fixed64)

TString

UTF-8 string

TBytes

Arbitrary byte sequence

TMessage

Nested message

TRepeated {FieldType}

Non-packed repeated field

TPacked {FieldType}

Packed repeated field (varint encoding)

`varint`

WireType

`fixed64`

WireType

`length-delim`

WireType

`fixed32`

WireType

`int32`

FieldType

`int64`

FieldType

`uint32`

FieldType

`uint64`

FieldType

`sint32`

FieldType

`sint64`

FieldType

`bool-type`

FieldType

`enum-type`

FieldType

`fixed32-type`

FieldType

`sfixed32`

FieldType

`float-type`

FieldType

`fixed64-type`

FieldType

`sfixed64`

FieldType

`double-type`

FieldType

`string-type`

FieldType

`bytes-type`

FieldType

`message-type`

FieldType

`repeated`

FieldType -> FieldType

`packed`

FieldType -> FieldType

`field-def`

Int -> String -> FieldType -> FieldDef

`message-def`

String -> List FieldDef -> MessageDef

`encode-field`

Encode a single field to bytes.

Parameters:

Returns:

Int -> FieldValue -> List Int

bytes = encode-field 1 (int 42)
# Returns: [8, 42] (tag for field 1 varint, value 42)

`encode`

Encode a complete protobuf message to bytes.

Parameters:

Returns:

List Field -> List Int

fields = [field 1 (int 42), field 2 (string "hello")]
bytes = encode fields

`decode`

Decode a complete protobuf message from bytes.

Parameters:

Returns:

List Int -> Result (List Field) ProtobufError

match decode bytes
  | Ok fields -> print "Decoded ${Int.to-string (List.length fields)} fields"
  | Err err -> print "Error: ${err}"

`int`

Create a varint integer field value (int32/int64/uint32/uint64).

Parameters:

Returns:

Int -> FieldValue

`uint`

Create an unsigned varint integer field value (alias for int).

Parameters:

Returns:

Int -> FieldValue

`sint`

Create a signed varint integer field value with zigzag encoding (sint32/sint64).

Parameters:

Returns:

Int -> FieldValue

`bool`

Create a boolean field value (encoded as varint 0 or 1).

Parameters:

Returns:

Bool -> FieldValue

`enum`

Create an enum field value (encoded as varint).

Parameters:

Returns:

Int -> FieldValue

`fixed32`

Create a fixed32 field value (fixed32/sfixed32/float).

Parameters:

Returns:

Int -> FieldValue

`sfixed32`

Create a signed fixed32 field value (alias for fixed32).

Parameters:

Returns:

Int -> FieldValue

`fixed64`

Create a fixed64 field value (fixed64/sfixed64/double).

Parameters:

Returns:

Int -> FieldValue

`sfixed64`

Create a signed fixed64 field value (alias for fixed64).

Parameters:

Returns:

Int -> FieldValue

`string`

Create a string field value.

Parameters:

Returns:

String -> FieldValue

`bytes`

Create a bytes field value.

Parameters:

Returns:

List Int -> FieldValue

`message`

Create a nested message field value.

Parameters:

Returns:

List Field -> FieldValue

`repeated-values`

Create a repeated field value (non-packed).

Parameters:

Returns:

List FieldValue -> FieldValue

`packed-ints`

Create a packed repeated integer field value.

Parameters:

Returns:

List Int -> FieldValue

`get-field`

Get a field by number from decoded message fields.

Parameters:

Returns:

List Field -> Int -> Option FieldValue

match get-field decoded-fields 1
  | Some value -> print "Found field 1"
  | None -> print "Field 1 not found"

`get-repeated`

Get all fields with a given number (for repeated fields).

Parameters:

Returns:

List Field -> Int -> List FieldValue

repeated-values = get-repeated decoded-fields 3
print "Found ${Int.to-string (List.length repeated-values)} values"

`as-int`

Extract varint as integer.

Parameters:

Returns:

FieldValue -> Option Int

`as-sint`

Extract varint as signed integer (with zigzag decoding).

Parameters:

Returns:

FieldValue -> Option Int

`as-bool`

Extract varint as boolean.

Parameters:

Returns:

FieldValue -> Option Bool

`as-fixed32`

Extract fixed32 value.

Parameters:

Returns:

FieldValue -> Option Int

`as-fixed64`

Extract fixed64 value.

Parameters:

Returns:

FieldValue -> Option Int

`as-bytes`

Extract bytes value.

Parameters:

Returns:

FieldValue -> Option (List Int)

`as-string`

Extract string value.

Parameters:

Returns:

FieldValue -> Option String

`as-message`

Extract embedded message as fields.

Parameters:

Returns:

FieldValue -> Result (List Field) ProtobufError

`as-packed-ints`

Extract packed repeated integers.

Parameters:

Returns:

FieldValue -> Result (List Int) ProtobufError

`field`

Create a Field record from field number and value.

Parameters:

Returns:

Int -> FieldValue -> Field

f = field 1 (int 42)
# Creates: { number: 1, wire-type: Varint, value: VarintValue 42 }

`bytes-to-hex`

Format bytes as hex string for debugging.

Parameters:

Returns:

List Int -> String

hex = bytes-to-hex [8, 42, 18, 5]
print "Encoded: ${hex}"

`inspect`

Print decoded message structure for debugging.

Parameters:

Returns:

List Field -> Unit

inspect decoded-fields
# Prints:
# Field 1:
#   varint: 42
# Field 2:
#   string: "hello"