enact 0.4.0.dev6

A framework for generative software.

enact - A Framework for Generative Software.

Enact is a python framework for building generative software, specifically software that integrates with machine learning models or APIs that generate distributions of outputs.

The advent of generative AI is driving changes in the way software is built. The unique challenges of implementing, maintaining and improving generative systems indicate a need to rethink the software stack from a first-principles perspective. See why-enact for a more in-depth discussion.

The design philosophy of enact is to provide an easy-to-use python framework that addresses the needs of emerging AI-based systems in a fundamental manner. Enact is designed as a core framework that provides low-level primitives required by generative software systems.

To this end, enact provides support for the following features:

• The ability to commit data, generative components and executions to persistent storage in a versioned manner.
• Journaled executions of generative python components.
• The ability to rewind and replay past executions.
• Easy interchangeability of human and AI-driven subsystems.
• Support for all of the above features in higher-order generative flows, i.e., generative programs that generate and execute other generative flows.
• A simple hash-based storage model that simplifies implementation of distributed and asynchronous generative systems.

Installation and overview

Enact is available as a pypi package and can be installed via:

pip install enact

Enact wraps generative components as python dataclasses with annotated input and output types:

import enact

import dataclasses
import random

@enact.typed_invokable(input_type=enact.NoneResource, output_type=enact.Int)
@dataclasses.dataclass
class RollDie(enact.Invokable):
  """An enact invokable that rolls a die."""
  sides: int

  def call(self):
    return enact.Int(random.randint(1, self.sides))

roll_die = RollDie(sides=6)
print(roll_die())  # Print score

Data and generative components can be committed to and checked out of persistent storage.

with enact.FileStore('./enact_store') as store:
  roll_die_v0 = enact.commit(roll_die)  # Return a reference.
  roll_die.sides = 20
  print(roll_die())                     # Roll 20 sided die.
  roll_die = roll_die_v0.checkout()     # Check out 6 sided die.
  print(roll_die())                     # Roll 6 sided die.

Executions can be journaled with the invoke command.

@enact.typed_invokable(enact.Int, enact.Int)
@dataclasses.dataclass
class RollDice(enact.Invokable):
  """Roll the indicated number of dice."""
  die: enact.Invokable

  def call(self, num_rolls: enact.Int):
    return enact.Int(sum(self.die() for _ in range(num_rolls)))

roll_dice = RollDice(roll_die)

with store:
  num_rolls = enact.commit(enact.Int(3))  # commit input to store.
  invocation = roll_dice.invoke(num_rolls)  # create journaled execution.
  print(invocation.get_output())  # Print sum of 3 rolls

Invocations allow investigating details of the execution and allow for advanced features such as rewind/replay.

# Print individual dice rolls.
with store:
  for i in range(3):
    roll_result = invocation.get_child(i).get_output()
    print(f'Roll {i} was {roll_result}')

# Rewind the last roll and replay it.
with store:
  two_rolls = invocation.rewind(1)        # Rewind by one call.
  print(two_rolls.replay().get_output())

See the quickstart and enact concepts for more information.

Documentation

Full documentation is work in progress. Please take a look at the 'examples' directory.

Why enact?

The rise of generative AI models is transforming the software development process.

Traditional software relies primarily on functional buildings blocks in which inputs and system state directly determine outputs. In contrast, modern software increasingly utilizes generative AI elements, in which each input is associated with a range of possible outputs.

This seemingly small change in emphasis - from functions to conditional distributions - implies a shift across multiple dimensions of the engineering process, summarized in the table below.

	Generative	Traditional
Building block	Conditional distributions	Deterministic functions
Engineering	Improve output distributions	Add features, debug errors
Subsystems	Unique	Interchangeable
Code sharing	Components	Frameworks
Executions	Training data	Logged for metrics/debugging
Interactivity	Within system components	At system boundaries
Code vs data	Overlapping	Distinct

Building generative software means fitting distributions

Generative AI can be used to quickly sketch out impressive end-to-end experiences. Prototypes of text-based agents, for instance, often involve little more than calling an API with a well-chosen prompt. Evolving such prototypes into production-ready systems can be non-trivial though, as they may show undesirable behaviors a certain percentage of the time, may fail to respond correctly to unusual user inputs or may simply fail to meet a softly defined quality target.

Where traditional engineering focuses on implementing features and fixing bugs, one of the major goals of generative software engineering is then to fit the conditional distribution represented by the system as a whole to a target distribution. This target may be specified implicitly, e.g., via sampled human inputs or corrections, or explicitly, e.g., by a task reward or example outputs.

In many cases, the process of ongoing finetuning and improvement does not have a clearly defined endpoint. This is a departure from traditional software engineering, where a feature - once it is implemented and bug-free - requires only maintenance-level engineering work.

In some cases, fine-tuning generative systems can be achieved directly using machine learning techniques and frameworks. For instance, systems that consist of a thin software wrapper around a single large language model (LLM) or text-to-image model may directly train the underlying model to shape system behavior.

In cases where multiple generative components work together or are called in autoregressive feedback loops, the system as a whole may need to be fit to the target distribution, which in addition to ML training may involve A/B testing between API-identical subsystems and the refinement of simple generative components into complex algorithmic flows that structure the generation process.

Fitting generative software is a recursive process.

In traditional software engineering, the choice between two API-identical implementations primarily revolves around practicalities such as performance or maintainability. However, in generative software, individual components produce distributions that may be more or less well-fitted to the system's overall goal, for example, one foundation text-to-image model may outperform another when the task is to generate images in a certain style, even though it might not be a better image generator in general.

Generative system outputs are distributions that optimized towards some, often implicitly specified, target. Data selection, training parameters, model composition, sampling of feedback and self-improvement flows produce systems whose conditional output distributions represent a unique, opinionated take on the problem they were trained to solve. Therefore the development of generative systems motivates ongoing reevaluation, tuning and replacement of subsystems, more so than in traditional engineering applications.

This optimization process involves, on the one hand, recursive elaboration, in which a component is replaced by a structured generative flow or algorithm. On the other hand, it involves 'compression' of the resulting data into end-to-end trained models. For example, a simple call into an LLM can be elaborated by exploring a tree of possible completions before settling on a final result, and the resulting executions could be used to fine-tune the original LLM.

Generative software is collaborative

There are many generative AI components that are mutually API-compatible (e.g., text-to-image generation, LLMs) but that cannot be directly ranked in terms of quality since they represent a unique take on the problem domain. The combination of API compatibility and variation lends itself to a more evolutionary, collaborative style than traditional software, where shared effort tends to centralize into fewer, lower-level frameworks.

This new collaborative approach is already evidenced by both widespread sharing of prompt templates and the existence of public databases of fine-tuned models.

Generative software reflects on its executions.

Many popular programming languages offer capacity for reflection, wherein the structure of code is programmatically interpretable by other code. In addition to this, generative software requires the ability to reflect on code executions.

A generative software system specifies a distribution of outputs only implicitly. Sampling from it may be computationally intensive and provides valuable information that may be used as system feedback or training data. Since generative software may include complex, recursive algorithms over generative components, this suggests a need for not simply tracking inputs and outputs at system boundaries, but at every level of execution.

This is particularly relevant to higher order generative flows, in which the output of one generative step structures the execution of the next: Such a system can use call traces as feedback to improve its output, in the same way that a human may use a debugger to step through an execution to debug an issue.

In contrast, conventional software tracks executions at a low level of resolution, e.g., using logging or monitoring frameworks, since their primary use is to ensure system health and debug errors that occur in deployment.

Humans are in the loop

Unlike traditional systems, where user interactions happen at system boundaries, AI and humans are often equal participants in generative computations. An example is Reinforcement Learning from Human Feedback (RLHF), where humans provide feedback on AI output, only to be replaced by an AI model that mimics their feedback behavior during the training process. In other cases, critical generative flows (e.g., the drafting of legal documents) may require a human verification step, without which the system provides subpar results.

The choice between sampling human input and sampling a generative model is involves considerations such as cost and quality, and may be subject to change during the development of a system. For example, an early deployment of a system may heavily sample outputs or feedback from human participants, until there is enough data to bootstrap the target distribution using automated generative components.

Therefore, a generative system should be designed to utilize human input in the same way it would interact with an API or subsystem.

Data is code, code is data

Traditional software systems tend to allow a clear distinction between code (written by developers) and data (generated by the user and the system). In generative systems this distinction breaks down: Approaches such as AutoGPT or Voyager use generative AI to generate programs (specified in code or plain text), which in turn may be interpreted by generative AI systems; prompts for chat-based generative AI could equally be considered code or data.

Development and Contributing

Enact is currently in alpha release. The framework is open source and Apache licensed. We are actively looking for contributors that are excited about the vision.

You can download the source code, report issues and create pull requests at https://github.com/agentic-ai/enact.