Type Mapping & Coverage

This page documents what q/kdb+ datatypes kdb_codec currently supports for IPC encoding/decoding, how those types map to Rust, and which q types are not supported yet.

Goals

• Safe decoding of untrusted IPC bytes (no panics, no OOM)
• Clear, explicit behavior for unsupported q types (return an error)

Supported q types (IPC)

The IPC encoder/decoder currently supports:

• Basic atoms/lists (KX 0–19, and their corresponding atom type ids)
  • bool, guid, byte, short, int, long, real, float, char/string, symbol
  • timestamp, month, date, datetime, timespan, minute, second, time
• Mixed list (compound list): type 0
• Table: type 98
• Dictionary / sorted dictionary: type 99 / 127
• General null: type 101
• Error: type -128

If the decoder encounters a q type that is not supported, it returns an error (typically Error::InvalidType).

Type mapping (q → Rust)

All q values are represented as the K struct. The following table summarizes the primary Rust types used by constructors/accessors.

q	Rust
bool	bool
GUID	[u8; 16]
byte	u8
short	i16
int	i32
long	i64
real	f32
float	f64
char	char
symbol	String
timestamp	chrono::DateTime<chrono::Utc>
month	chrono::NaiveDate
date	chrono::NaiveDate
datetime	chrono::DateTime<chrono::Utc>
timespan	chrono::Duration
minute	chrono::Duration
second	chrono::Duration
time	chrono::Duration
list	Vec<Item>
compound list	Vec<K>
table	Vec<K>
dictionary	Vec<K>
null	()

Missing / not supported yet

Compared to the full datatype taxonomy described in KX documentation, the following categories are currently not supported by the IPC encoder/decoder:

• Enums (KX 20–76)
• Nested/other types (KX 77+)
• Function/derived/iterator types (KX 100–112)
• Foreign objects (type 112)

For implementation notes and deeper coverage discussions, please refer to the documentation site and repository history.

Extending coverage

If you want to add support for additional q types, the typical work involves:

• Extending the internal K representation to carry the new payloads
• Adding safe deserialization in the IPC decoder (bounds checks + resource limits)
• Mirroring serialization support if round-trip is required
• Adding tests + fuzz coverage