Merge pull request #78 from ljoukov/functions

Add support for "functions" in OpenAI chat completion APIs.

Demo/App/APIProvidedView.swift

@@ -42,7 +42,9 @@ struct APIProvidedView: View {
             miscStore: miscStore
         )
         .onChange(of: apiKey) { newApiKey in
-            chatStore.openAIClient = OpenAI(apiToken: newApiKey)
+            let client = OpenAI(apiToken: newApiKey)
+            chatStore.openAIClient = client
+            miscStore.openAIClient = client
         }
     }
 }

Demo/DemoChat/Sources/ChatStore.swift

@@ -85,22 +85,53 @@ public final class ChatStore: ObservableObject {
                 return
             }
 
+            let weatherFunction = ChatFunctionDeclaration(
+                name: "getWeatherData",
+                description: "Get the current weather in a given location",
+                parameters: .init(
+                  type: .object,
+                  properties: [
+                    "location": .init(type: .string, description: "The city and state, e.g. San Francisco, CA")
+                  ],
+                  required: ["location"]
+                )
+            )
+
+            let functions = [weatherFunction]
+
             let chatsStream: AsyncThrowingStream<ChatStreamResult, Error> = openAIClient.chatsStream(
                 query: ChatQuery(
                     model: model,
                     messages: conversation.messages.map { message in
                         Chat(role: message.role, content: message.content)
-                    }
+                    },
+                    functions: functions
                 )
             )
 
+            var functionCallName = ""
+            var functionCallArguments = ""
             for try await partialChatResult in chatsStream {
                 for choice in partialChatResult.choices {
                     let existingMessages = conversations[conversationIndex].messages
+                    // Function calls are also streamed, so we need to accumulate.
+                    if let functionCallDelta = choice.delta.functionCall {
+                        if let nameDelta = functionCallDelta.name {
+                          functionCallName += nameDelta
+                        }
+                        if let argumentsDelta = functionCallDelta.arguments {
+                          functionCallArguments += argumentsDelta
+                        }
+                    }
+                    var messageText = choice.delta.content ?? ""
+                    if let finishReason = choice.finishReason,
+                       finishReason == "function_call" {
+                        messageText += "Function call: name=\(functionCallName) arguments=\(functionCallArguments)"
+                    }
                     let message = Message(
                         id: partialChatResult.id,
                         role: choice.delta.role ?? .assistant,
-                        content: choice.delta.content ?? "",
+                        content: messageText,
                         createdAt: Date(timeIntervalSince1970: TimeInterval(partialChatResult.created))
                     )
                     if let existingMessageIndex = existingMessages.firstIndex(where: { $0.id == partialChatResult.id }) {

Demo/DemoChat/Sources/UI/DetailView.swift

@@ -17,9 +17,9 @@ struct DetailView: View {
     @State var inputText: String = ""
     @FocusState private var isFocused: Bool
     @State private var showsModelSelectionSheet = false
-    @State private var selectedChatModel: Model = .gpt3_5Turbo
+    @State private var selectedChatModel: Model = .gpt4_0613
 
-    private let availableChatModels: [Model] = [.gpt3_5Turbo, .gpt4]
+    private let availableChatModels: [Model] = [.gpt3_5Turbo0613, .gpt4_0613]
 
     let conversation: Conversation
     let error: Error?
@@ -237,6 +237,14 @@ struct ChatBubble: View {
                     .foregroundColor(userForegroundColor)
                     .background(userBackgroundColor)
                     .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
+            case .function:
+              Text(message.content)
+                  .font(.footnote.monospaced())
+                  .padding(.horizontal, 16)
+                  .padding(.vertical, 12)
+                  .background(assistantBackgroundColor)
+                  .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
+              Spacer(minLength: 24)
             case .system:
                 EmptyView()
             }
@@ -252,7 +260,14 @@ struct DetailView_Previews: PreviewProvider {
                 messages: [
                     Message(id: "1", role: .assistant, content: "Hello, how can I help you today?", createdAt: Date(timeIntervalSinceReferenceDate: 0)),
                     Message(id: "2", role: .user, content: "I need help with my subscription.", createdAt: Date(timeIntervalSinceReferenceDate: 100)),
-                    Message(id: "3", role: .assistant, content: "Sure, what seems to be the problem with your subscription?", createdAt: Date(timeIntervalSinceReferenceDate: 200))
+                    Message(id: "3", role: .assistant, content: "Sure, what seems to be the problem with your subscription?", createdAt: Date(timeIntervalSinceReferenceDate: 200)),
+                    Message(id: "4", role: .function, content:
+                              """
+                              get_current_weather({
+                                "location": "Glasgow, Scotland",
+                                "format": "celsius"
+                              })
+                              """, createdAt: Date(timeIntervalSinceReferenceDate: 200))
                 ]
             ),
             error: nil,

README.md

@@ -208,6 +208,8 @@ Using the OpenAI Chat API, you can build your own applications with `gpt-3.5-tur
      public let model: Model
      /// The messages to generate chat completions for
      public let messages: [Chat]
+     /// A list of functions the model may generate JSON inputs for.
+     public let functions: [ChatFunctionDeclaration]?
      /// What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and  We generally recommend altering this or top_p but not both.
      public let temperature: Double?
      /// An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.
@@ -318,6 +320,61 @@ for try await result in openAI.chatsStream(query: query) {
 }
 ```
 
+**Function calls**
+```swift
+let openAI = OpenAI(apiToken: "...")
+// Declare functions which GPT-3 might decide to call.
+let functions = [
+  ChatFunctionDeclaration(
+      name: "get_current_weather",
+      description: "Get the current weather in a given location",
+      parameters:
+        JSONSchema(
+          type: .object,
+          properties: [
+            "location": .init(type: .string, description: "The city and state, e.g. San Francisco, CA"),
+            "unit": .init(type: .string, enumValues: ["celsius", "fahrenheit"])
+          ],
+          required: ["location"]
+        )
+  )
+]
+let query = ChatQuery(
+  model: "gpt-3.5-turbo-0613",  // 0613 is the earliest version with function calls support.
+  messages: [
+      Chat(role: .user, content: "What's the weather like in Boston?")
+  ],
+  functions: functions
+)
+let result = try await openAI.chats(query: query)
+```
+
+Result will be (serialized as JSON here for readability):
+```json
+{
+  "id": "chatcmpl-1234",
+  "object": "chat.completion",
+  "created": 1686000000,
+  "model": "gpt-3.5-turbo-0613",
+  "choices": [
+    {
+      "index": 0,
+      "message": {
+        "role": "assistant",
+        "function_call": {
+          "name": "get_current_weather",
+          "arguments": "{\n  \"location\": \"Boston, MA\"\n}"
+        }
+      },
+      "finish_reason": "function_call"
+    }
+  ],
+  "usage": { "total_tokens": 100, "completion_tokens": 18, "prompt_tokens": 82 }
+}
+
+```
+
+
 Review [Chat Documentation](https://platform.openai.com/docs/guides/chat) for more info.
 
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