dspy

# DSPy: Declarative Language Model Programming

## When to Use This Skill

Use DSPy when you need to:
- **Build complex AI systems** with multiple components and workflows
- **Program LMs declaratively** instead of manual prompt engineering
- **Optimize prompts automatically** using data-driven methods
- **Create modular AI pipelines** that are maintainable and portable
- **Improve model outputs systematically** with optimizers
- **Build RAG systems, agents, or classifiers** with better reliability

**GitHub Stars**: 22,000+ | **Created By**: Stanford NLP

## Installation

```bash
# Stable release
pip install dspy

# Latest development version
pip install git+https://github.com/stanfordnlp/dspy.git

# With specific LM providers
pip install dspy[openai]        # OpenAI
pip install dspy[anthropic]     # Anthropic Claude
pip install dspy[all]           # All providers
```

## Quick Start

### Basic Example: Question Answering

```python
import dspy

# Configure your language model
lm = dspy.Claude(model="claude-sonnet-4-5-20250929")
dspy.settings.configure(lm=lm)

# Define a signature (input → output)
class QA(dspy.Signature):
    """Answer questions with short factual answers."""
    question = dspy.InputField()
    answer = dspy.OutputField(desc="often between 1 and 5 words")

# Create a module
qa = dspy.Predict(QA)

# Use it
response = qa(question="What is the capital of France?")
print(response.answer)  # "Paris"
```

### Chain of Thought Reasoning

```python
import dspy

lm = dspy.Claude(model="claude-sonnet-4-5-20250929")
dspy.settings.configure(lm=lm)

# Use ChainOfThought for better reasoning
class MathProblem(dspy.Signature):
    """Solve math word problems."""
    problem = dspy.InputField()
    answer = dspy.OutputField(desc="numerical answer")

# ChainOfThought generates reasoning steps automatically
cot = dspy.ChainOfThought(MathProblem)

response = cot(problem="If John has 5 apples and gives 2 to Mary, how many does he have?")
print(response.rationale)  # Shows reasoning steps
print(response.answer)     # "3"
```

## Core Concepts

### 1. Signatures

Signatures define the structure of your AI task (inputs → outputs):

```python
# Inline signature (simple)
qa = dspy.Predict("question -> answer")

# Class signature (detailed)
class Summarize(dspy.Signature):
    """Summarize text into key points."""
    text = dspy.InputField()
    summary = dspy.OutputField(desc="bullet points, 3-5 items")

summarizer = dspy.ChainOfThought(Summarize)
```

**When to use each:**
- **Inline**: Quick prototyping, simple tasks
- **Class**: Complex tasks, type hints, better documentation

### 2. Modules

Modules are reusable components that transform inputs to outputs:

#### dspy.Predict
Basic prediction module:

```python
predictor = dspy.Predict("context, question -> answer")
result = predictor(context="Paris is the capital of France",
                   question="What is the capital?")
```

#### dspy.ChainOfThought
Generates reasoning steps before answering:

```python
cot = dspy.ChainOfThought("question -> answer")
result = cot(question="Why is the sky blue?")
print(result.rationale)  # Reasoning steps
print(result.answer)     # Final answer
```

#### dspy.ReAct
Agent-like reasoning with tools:

```python
from dspy.predict import ReAct

class SearchQA(dspy.Signature):
    """Answer questions using search."""
    question = dspy.InputField()
    answer = dspy.OutputField()

def search_tool(query: str) -> str:
    """Search Wikipedia."""
    # Your search implementation
    return results

react = ReAct(SearchQA, tools=[search_tool])
result = react(question="When was Python created?")
```

#### dspy.ProgramOfThought
Generates and executes code for reasoning:

```python
pot = dspy.ProgramOfThought("question -> answer")
result = pot(question="What is 15% of 240?")
# Generates: answer = 240 * 0.15
```

### 3. Optimizers

Optimizers improve your modules automatically using training data:

#### BootstrapFewShot
Learns from examples:

```python
from dspy.teleprompt import BootstrapFewShot

# Training data
trainset = [
    dspy.Example(question="What is 2+2?", answer="4").with_inputs("question"),
    dspy.Example(question="What is 3+5?", answer="8").with_inputs("question"),
]

# Define metric
def validate_answer(example, pred, trace=None):
    return example.answer == pred.answer

# Optimize
optimizer = BootstrapFewShot(metric=validate_answer, max_bootstrapped_demos=3)
optimized_qa = optimizer.compile(qa, trainset=trainset)

# Now optimized_qa performs better!
```

#### MIPRO (Most Important Prompt Optimization)
Iteratively improves prompts:

```python
from dspy.teleprompt import MIPRO

optimizer = MIPRO(
    metric=validate_answer,
    num_candidates=10,
    init_temperature=1.0
)

optimized_cot = optimizer.compile(
    cot,
    trainset=trainset,
    num_trials=100
)
```

#### BootstrapFinetune
Creates datasets for model fine-tuning:

```python
from dspy.teleprompt import BootstrapFinetune

optimizer = BootstrapFinetune(metric=validate_answer)
optimized_module = optimizer.compile(qa, trainset=trainset)

# Exports training data for fine-tuning
```

### 4. Building Complex Systems

#### Multi-Stage Pipeline

```python
import dspy

class MultiHopQA(dspy.Module):
    def __init__(self):
        super().__init__()
        self.retrieve = dspy.Retrieve(k=3)
        self.generate_query = dspy.ChainOfThought("question -> search_query")
        self.generate_answer = dspy.ChainOfThought("context, question -> answer")

    def forward(self, question):
        # Stage 1: Generate search query
        search_query = self.generate_query(question=question).search_query

        # Stage 2: Retrieve context
        passages = self.retrieve(search_query).passages
        context = "\n".join(passages)

        # Stage 3: Generate answer
        answer = self.generate_answer(context=context, question=question).answer
        return dspy.Prediction(answer=answer, context=context)

# Use the pipeline
qa_system = MultiHopQA