All standard C++ library conforming allocators have to support the minimal interface requirements. Beyond these requirements, some examples of fully defined allocators are LLVM's latest standard C++ library implementation of std::allocator, and a custom allocator I've written called ThreadLocalAllocator. These are both examples of what's been categorized as "stateless" allocators. Alternatively, allocators can be "stateful".

A pattern for building personal knowledge bases using LLMs.

This is an idea file, it is designed to be copy pasted to your own LLM Agent (e.g. OpenAI Codex, Claude Code, OpenCode / Pi, or etc.). Its goal is to communicate the high level idea, but your agent will build out the specifics in collaboration with you.

Most people's experience with LLMs and documents looks like RAG: you upload a collection of files, the LLM retrieves relevant chunks at query time, and generates an answer. This works, but the LLM is rediscovering knowledge from scratch on every question. There's no accumulation. Ask a subtle question that requires synthesizing five documents, and the LLM has to find and piece together the relevant fragments every time. Nothing is built up. NotebookLM, ChatGPT file uploads, and most RAG systems work this way.