banks

2.4.1 · active · verified Thu Apr 09

Banks (version 2.4.1) is a Python library designed as a prompt programming language for Large Language Models (LLMs). It simplifies the creation, templating, versioning, and management of LLM prompts, offering an intuitive alternative to f-strings for complex prompt engineering. The library maintains an active and frequent release cadence, continuously adding features and improvements.

Warnings

gotcha Python 3.9 compatibility was temporarily removed in v2.3.0 (stopping testing) but re-added in v2.4.1. Users on Python 3.9 should ensure they are using Banks v2.4.1 or newer to avoid compatibility issues.
Fix: Upgrade to Banks v2.4.1 or later if using Python 3.9. Consider using Python 3.10+ for broader compatibility.
breaking In v1.8.0, `litellm` and `redis` transitioned from direct requirements to optional dependencies. If your application relies on features that use these libraries (e.g., LLM text generation within prompts or caching), you must install Banks with the `[all]` extra (e.g., `pip install "banks[all]"`).
Fix: Modify your installation command to `pip install "banks[all]"` or install specific extras like `"banks[litellm]"` if only certain optional features are needed.
gotcha For asynchronous operations, the environment variable `BANKS_ASYNC_ENABLED` must be set to `true`, and you should use the `AsyncPrompt` class instead of `Prompt`. Failure to set the environment variable will result in synchronous behavior even with `AsyncPrompt`.
Fix: Set `os.environ['BANKS_ASYNC_ENABLED'] = 'true'` before initializing your application, and ensure you are importing and using `AsyncPrompt` where async functionality is desired.
breaking Version 2.0.0 introduced breaking changes specifically related to dependencies, noted as `[breaking] fix deps again`. Users upgrading from versions prior to 2.0.0 may encounter issues with their dependency tree.
Fix: Review the Banks v2.0.0 changelog and your project's dependency resolution. It might be necessary to recreate virtual environments or manually update/pin specific dependency versions.

Install

pip install banks Core library
pip install "banks[all]" With optional dependencies (litellm, redis)

Imports

Prompt
```
from banks import Prompt
```
DirectoryTemplateRegistry
```
from banks.registries import DirectoryTemplateRegistry
```
Used for loading templates from the filesystem.

Quickstart

This example demonstrates how to define a multi-turn chat prompt using Banks' templating syntax and then render it into a list of chat messages suitable for Large Language Model (LLM) APIs.

from banks import Prompt

# Define a prompt template using Banks' templating language
prompt_template = """
{% chat role="system" %}
You are a {{ persona }}.
{% endchat %}

{% chat role="user" %}
Hello {{ name }}!
{% endchat %}
"""

# Create a Prompt object
p = Prompt(prompt_template)

# Render the prompt with context to generate chat messages
chat_messages = p.chat_messages({"persona": "friendly assistant", "name": "Alice"})

# Print the generated chat messages (e.g., for use with an LLM client)
print(chat_messages)

# Expected output:
# [{'role': 'system', 'content': 'You are a friendly assistant.'},
#  {'role': 'user', 'content': 'Hello Alice!'}]

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