# Chat Bot Mistakes Rust Vecs

> Source: <https://www.dotnetperls.com/2026_8_12_chat-bot-mistakes-rust-vecs>
> Published: 2026-08-12 07:00:00+00:00

Today I was using an **online chat bot** (a well-known one) and exploring changes to my Rust code. The chat bot confidently told me that in Rust a `Vec`

of `bool`

is encoded as a single bit per `bool`

. I even asked if this was "truly" the case in Rust, as I was not familiar with this.

In Rust the `Vec`

type does not tend to have type-specific optimizations like for `bool`

. It is **supposed** to be **simple**. The chat bot explained that yes, in Rust a Vector of bools only requires 1 bit per `bool`

.

This is not correct. A `bool`

requires 1 byte in Rust, and 1 byte is 8 bits. Further online searches **supported** this—the chat bot was **confidently wrong**.

I created a test program that allocated **100 million bools** in a `Vec`

, and then used the bools in an infinite loop. It required about 100000 kB, which means that about 1000 bools fit in 1 kB of memory. Which means that 1 `bool`

requires about 1 byte. There has to be some source of truth—and AI chat bots can be wrong.