The RESP Wire Format

You've been using RESP already — now let's understand it fully.

The Five RESP2 Types

Why Two String Types?

Simple strings (+) can't contain \r or \n — they're terminated by CRLF. Fine for OK and PONG.

Bulk strings ($) use length-prefixing, so they can contain any bytes — including newlines, nulls, binary data. This is how Redis is "binary safe."

The Null Bulk String

$-1\r\n means "this value doesn't exist" — like null/nil/None. You'll return this for missing keys.

Your Serializer

Build functions for all five types:

• encode_simple_string(s) → +s\r\n
• encode_error(msg) → -msg\r\n
• encode_integer(n) → :n\r\n
• encode_bulk_string(s) → $len\r\ns\r\n (or $-1\r\n for null)
• encode_array(items) → *count\r\n + items

Unknown Commands

When your Redis receives a command it doesn't recognize, return: -ERR unknown command '<cmd>'\r\n