LangChain.dart streaming

streaming.dart

import 'dart:io';

import 'package:langchain/langchain.dart';
import 'package:langchain_openai/langchain_openai.dart';
import 'package:langchain_ollama/langchain_ollama.dart';

Future<void> option1() async {
  final openaiApiKey = Platform.environment['OPENAI_API_KEY'];
  
  final chatModel = ChatOpenAI(apiKey: openaiApiKey);
  
  final messages = [
    ChatMessage.system(
      'You are a helpful assistant that replies only with numbers '
          'in order without any spaces or commas',
    ),
    ChatMessage.humanText('List the numbers from 1 to 9'),
  ];
  
  final stream = chatModel.stream(PromptValue.chat(messages));
  await for (final ChatResult res in stream) {
    print(res.firstOutputAsString);
  }
  // 123
  // 456
  // 789
}

Future<void> option2() async {
  final openaiApiKey = Platform.environment['OPENAI_API_KEY'];

  final chatModel = ChatOpenAI(apiKey: openaiApiKey);
  final chain = chatModel.pipe(StringOutputParser());

  final messages = [
    ChatMessage.system(
      'You are a helpful assistant that replies only with numbers '
          'in order without any spaces or commas',
    ),
    ChatMessage.humanText('List the numbers from 1 to 9'),
  ];

  final stream = chain.stream(PromptValue.chat(messages));
  await for (final String res in stream) {
    print(res);
  }
  // 123
  // 456
  // 789
}

Future<void> ollama() async {
  final chatModel = ChatOllama(
    defaultOptions: ChatOllamaOptions(
      model: 'llama2:latest',
    ),
  );

  final messages = [
    ChatMessage.system(
      'You are a helpful assistant that replies only with numbers '
          'in order without any spaces or commas',
    ),
    ChatMessage.humanText('List the numbers from 1 to 9'),
  ];

  final stream = chatModel.stream(PromptValue.chat(messages));
  await for (final ChatResult res in stream) {
    print(res.firstOutputAsString);
  }
  // 1
  // 2
  // 3
  // 4
  // 5
  // 6
  // 7
  // 8
  // 9
}