Match each framework property to the declarative or imperative paradigm it belongs to

LLM frameworks split into two camps based on what artefact you, the developer, are responsible for producing. Imperative frameworks (LangChain, LlamaIndex) ask you to write the prompt and wire the steps. You compose a chain, `prompt | model | parser` in LangChain's pipe syntax, and you can pause execution between any two steps to inspect what is happening. The mental model is 'plumbing': you connect named primitives in a specific order. Declarative frameworks (DSPy, BAML) ask you to declare a signature ('this function takes a question and returns an answer') and a metric ('the answer is correct if it exact-matches the gold label'). The framework's compiler then searches over prompt templates and few-shot exemplars to maximise the metric on your training set. You do not write the prompt; the compiler does. The matching question turns on three tells. If the property names a metric, a compiler, or optimizer-chosen exemplars, it is declarative. If it names a prompt string, a Runnable, or a pipe composition, it is imperative.

The split is about which artefact the developer owns. In **imperative** frameworks like LangChain and LlamaIndex, you write the prompt string and wire each step explicitly. The unit of composition is something like a Runnable or a QueryEngine; you build a pipeline with the pipe operator or method chaining, and you can step through any intermediate state. The trade-off is power for control. You can build anything, but every prompt is yours to maintain. In **declarative** frameworks like DSPy and BAML, you declare a signature (input fields, output fields, semantic description) plus a metric, and the framework compiles a prompt and a set of few-shot exemplars that maximise the metric on labelled data. The mental model is borrowed from PyTorch: program + optimizer + metric. You do not author the prompt; the compiler does, and re-compiles when the model, the data, or the metric changes. Matching the properties: prompt authoring, Runnable inspectability, and pipe composition are imperative tells. Signature-driven compilation, optimizer-selected exemplars, and the program plus optimizer plus metric framing are declarative tells. The two paradigms are not religious; production teams mix them. Declarative for the prompt-sensitive core, imperative for the surrounding orchestration.