trove/codec

Codecs for serializing keys and values to and from BitArray.

A Codec(a) pairs an encode function with a decode function. Built-in codecs cover strings, integers, and raw bytes. For custom types, construct a Codec directly with your own encode/decode functions.

Custom codecs must satisfy decode(encode(v)) == Ok(v) and produce deterministic output (same value always encodes to the same bytes).

Types

Codec

</>

A codec that can serialize a value of type a to BitArray and back.

Built-in codecs cover common types. For custom types, construct a Codec directly:

let float_codec = codec.Codec(
  encode: fn(f) { <<f:float>> },
  decode: fn(bits) {
    case bits {
      <<f:float>> -> Ok(f)
      _ -> Error(Nil)
    }
  },
)

pub type Codec(a) {
  Codec(
    encode: fn(a) -> BitArray,
    decode: fn(BitArray) -> Result(a, Nil),
  )
}

Constructors

Codec(
  encode: fn(a) -> BitArray,
  decode: fn(BitArray) -> Result(a, Nil),
)

Values

bit_array

</>

pub fn bit_array() -> Codec(BitArray)

Identity codec for raw bytes. Encodes and decodes as-is.

let c = codec.bit_array()
let bits = c.encode(<<1, 2, 3>>)
let assert Ok(<<1, 2, 3>>) = c.decode(bits)

int

</>

pub fn int() -> Codec(Int)

64-bit big-endian signed integer codec (two’s complement). Values outside the signed 64-bit range (-2^63 to 2^63 - 1) silently wrap on encode.

Note: This means decode(encode(v)) may not equal Ok(v) for values outside the signed 64-bit range. If you need arbitrary-precision integers, provide a custom codec.

let c = codec.int()
let bits = c.encode(42)
let assert Ok(42) = c.decode(bits)

string

</>

pub fn string() -> Codec(String)

UTF-8 string codec.

let c = codec.string()
let bits = c.encode("hello")
let assert Ok("hello") = c.decode(bits)