effect-ai-prompt

Effect AI Prompt Construction

Master the Effect AI Prompt API for building type-safe conversations with language models.

Import Patterns

CRITICAL: Always use namespace imports:

import * as Prompt from 'effect/unstable/ai/Prompt';
import * as Response from 'effect/unstable/ai/Response';
import { pipe } from 'effect';

When to Use This Skill

• Constructing messages for language model requests
• Building multi-turn conversation history
• Adding system instructions to prompts
• Integrating tool calls and results into conversations
• Converting streaming responses to prompt history
• Managing file/image attachments in messages
• Implementing custom chat interfaces

Conceptual Model

-- Message hierarchy
type Message = SystemMessage | UserMessage | AssistantMessage | ToolMessage
type Part =
  | TextPart
  | ReasoningPart
  | FilePart
  | ToolCallPart
  | ToolResultPart
  | ToolApprovalRequestPart
  | ToolApprovalResponsePart

-- Composition
Prompt.make       :: RawInput → Prompt
Prompt.concat      :: (Prompt, RawInput) → Prompt
Prompt.setSystem  :: (Prompt, String) → Prompt

-- History transformation
fromResponseParts :: ReadonlyArray<Response.Part> → Prompt

Message Types

Each message has role and content. Content is an array of Part objects.

System Messages

import * as Prompt from 'effect/unstable/ai/Prompt';

// String content only
const system = Prompt.makeMessage('system', {
	content: 'You are a helpful assistant specialized in mathematics.'
});

// Shorthand constructor
const systemShorthand = Prompt.systemMessage({
	content: 'You are a helpful assistant specialized in mathematics.'
});

// System message with options
const systemWithOptions = Prompt.makeMessage('system', {
	content: 'You are an expert coder.',
	options: {
		anthropic: { cache_control: { type: 'ephemeral' } }
	}
});

User Messages

// Text-only user message
const userText = Prompt.makeMessage("user", {
  content: [
    Prompt.makePart("text", { text: "What is 2+2?" })
  ]
})

// Shorthand constructor
const userShorthand = Prompt.userMessage({
  content: [
    Prompt.makePart("text", { text: "What is 2+2?" })
  ]
})

// Multimodal user message (text + file)
const userMultimodal = Prompt.makeMessage("user", {
  content: [
    Prompt.makePart("text", { text: "What's in this image?" }),
    Prompt.makePart("file", {
      mediaType: "image/jpeg",
      fileName: "photo.jpg",
      data: new Uint8Array([...])
    })
  ]
})