Add support for Functions

chat/chat.go

@@ -42,6 +42,9 @@ type CreateCompletionParams struct {
 	Stop     []string   `json:"stop,omitempty"`
 	Stream   bool       `json:"stream,omitempty"`
 
+	Functions    []Function `json:"functions,omitempty"`
+	FunctionCall string     `json:"function_call,omitempty"`
+
 	N           int     `json:"n,omitempty"`
 	TopP        float64 `json:"top_p,omitempty"`
 	Temperature float64 `json:"temperature,omitempty"`
@@ -70,9 +73,10 @@ type Choice struct {
 }
 
 type Message struct {
-	Role    string `json:"role,omitempty"`
-	Content string `json:"content,omitempty"`
-	Name    string `json:"name,omitempty"`
+	Role         string        `json:"role,omitempty"`
+	Content      string        `json:"content,omitempty"`
+	Name         string        `json:"name,omitempty"`
+	FunctionCall *FunctionCall `json:"function_call,omitempty"`
 }
 
 func (c *Client) CreateCompletion(ctx context.Context, p *CreateCompletionParams) (*CreateCompletionResponse, error) {

chat/function.go

@@ -0,0 +1,67 @@
+package chat
+
+import "encoding/json"
+
+// EmptyParameters is an empty parameter object used for a Function that accepts no arguments.
+var EmptyParameters = Schema{
+	Type:       "object",
+	Properties: map[string]Schema{},
+}
+
+const (
+	// FunctionCallAuto indicates the model should decide whether to call the function.
+	// This is default when Functions are provided.
+	FunctionCallAuto = "auto"
+
+	// FunctionCallNone indicates the mode should not call any functions.
+	// This is the default when no Functions are provided.
+	FunctionCallNone = "none"
+)
+
+// Schema defines a schema for a JSON object.
+//
+// See https://json-schema.org/understanding-json-schema/
+type Schema struct {
+	Type        string            `json:"type"`
+	Description string            `json:"description,omitempty"`
+	Properties  map[string]Schema `json:"properties"`
+	Required    []string          `json:"required,omitempty"`
+
+	// NOTE adding new fields may require updating the MarshalJSON method.
+}
+
+func (s Schema) MarshalJSON() ([]byte, error) {
+	type Alias Schema
+
+	// If Properties is nil marshal it without the Properties field.  This,
+	// rather than relying on omitempty, allows us to distinguish between an
+	// empty map (which is needed for valid API requests) and a nil map (which
+	// is needed for the default value).
+	if s.Properties == nil {
+		return json.Marshal(&struct {
+			Type        string   `json:"type"`
+			Description string   `json:"description,omitempty"`
+			Required    []string `json:"required,omitempty"`
+		}{
+			Type:        s.Type,
+			Description: s.Description,
+			Required:    s.Required,
+		})
+	}
+
+	return json.Marshal((*Alias)(&s))
+}
+
+// Function is a function the model may generate JSON inputs for
+type Function struct {
+	Name        string `json:"name"`
+	Description string `json:"description,omitempty"`
+	Parameters  Schema `json:"parameters"`
+}
+
+// FunctionCall is the name and arguments of a function that should be called,
+// as generated by the model.
+type FunctionCall struct {
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"`
+}