​
Overview

PromptL integrates seamlessly with Anthropic’s API by using the Anthropic adapter. This ensures prompts are formatted correctly for their API and Node.js SDK, allowing you to generate dynamic prompts with ease.
System Message Limitations: Anthropic does not support system messages in the messages array. Instead:
  • PropmtL will automatically move the first system message to the config object.
  • System messages are not allowed after messages from other roles, and it will throw an error.
  • Since system messages are moved to the configuration section, Anthropic will fail if there are no other user or assistant messages in the conversation.

​
Basic Example

Here’s how to use PromptL with Anthropic’s API: 
import Anthropic from '@anthropic-ai/sdk'
import { Adapters, render } from 'promptl-ai'

const prompt = `
---
model: claude-3-opus-20240229
max_tokens: 1024
---

<user>
  Generate a joke about {{ topic }}.
</user>
`

const { messages, config } = await render({
  prompt,
  parameters: { topic: 'chickens' },
  adapter: Adapters.anthropic, // Specify the Anthropic adapter
})

const client = new Anthropic({ apiKey: YOUR_ANTHROPIC_API_KEY })
const response = await client.messages.create({
  ...config,
  messages,
})

console.log(response.content[0].text)

​
Key Features

  1. Adapter-Specific Behavior:
    • System messages are extracted and placed in the config object.
    • The messages array must contain non-system messages.
  2. Formatting: PromptL formats messages in the format expected by Anthropic, ensuring compatibility.
  3. Support for Claude Models: Works seamlessly with Anthropic’s Claude family of models.

​
Troubleshooting

  1. Empty Messages Array:
    • Ensure your prompt contains non-system messages. Anthropic’s API does not allow an empty messages array.
  2. Check Configuration:
    • Anthropic always requires to define at least a model and max_tokens configuration.
  3. Error Handling: 
    try {
  const response = await client.messages.create({
    ...config,
    messages,
  })
  console.log(response.content[0].text)
} catch (error) {
  console.error('Error with Anthropic API:', error)
}

​
Next Steps