Programs should take an init type/function as the first argument

This is in line with the way Elm works. Also update examples.

examples/fullscreen/main.go

@@ -17,12 +17,16 @@ type tickMsg struct{}
 func main() {
 	tea.Fullscreen()
 	defer tea.ExitFullscreen()
-	err := tea.NewProgram(model(5), update, view, []tea.Sub{tick}).Start()
+	err := tea.NewProgram(initialize, update, view, []tea.Sub{tick}).Start()
 	if err != nil {
 		log.Fatal(err)
 	}
 }
 
+func initialize() (tea.Model, tea.Cmd) {
+	return model(5), nil
+}
+
 func update(message tea.Msg, mdl tea.Model) (tea.Model, tea.Cmd) {
 	m, _ := mdl.(model)
 

examples/input/go.mod

@@ -1,5 +0,0 @@
-module input-example
-
-go 1.13
-
-require github.com/charmbracelet/teaparty v0.0.0-20200118155738-c83a0bee59b9 // indirect

examples/input/go.sum

@@ -1,6 +0,0 @@
-github.com/charmbracelet/tea v0.0.0-20200118154546-df52853f9d94 h1:m2xhUqOw6OcefbPBR9Il0J0n0gB1663NoKU+vvkiLdU=
-github.com/charmbracelet/tea v0.0.0-20200118154546-df52853f9d94/go.mod h1:lijy1lXOKNwMjBu/jTT/DvR8yE9PhtX2olGFsCz9/Vk=
-github.com/charmbracelet/teaparty v0.0.0-20200118155738-c83a0bee59b9 h1:YQvJgppGVexnzIJ+KJlK9lBYA3+zXfdqZO/5Ngedtb0=
-github.com/charmbracelet/teaparty v0.0.0-20200118155738-c83a0bee59b9/go.mod h1:z8JWtuxM0oA+dZfi7BkgBW2YGbyOTbWAixFs46W3SK4=
-github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942 h1:A7GG7zcGjl3jqAqGPmcNjd/D9hzL95SuoOQAaFNdLU0=
-github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942/go.mod h1:eCbImbZ95eXtAUIbLAuAVnBnwf83mjf6QIVH8SHYwqQ=

examples/input/main.go

@@ -22,10 +22,7 @@ func main() {
 	tea.UseSysLog("tea")
 
 	p := tea.NewProgram(
-		Model{
-			Input: input.DefaultModel(),
-			Error: nil,
-		},
+		initialize,
 		update,
 		view,
 		[]tea.Sub{
@@ -46,6 +43,13 @@ func main() {
 	}
 }
 
+func initialize() (tea.Model, tea.Cmd) {
+	return Model{
+		Input: input.DefaultModel(),
+		Error: nil,
+	}, nil
+}
+
 func update(msg tea.Msg, model tea.Model) (tea.Model, tea.Cmd) {
 	var cmd tea.Cmd
 	m, ok := model.(Model)

examples/simple/main.go

@@ -21,12 +21,16 @@ type TickMsg struct{}
 
 func main() {
 	// Initialize our program
-	p := tea.NewProgram(Model(5), update, view, []tea.Sub{tick})
+	p := tea.NewProgram(initialize, update, view, []tea.Sub{tick})
 	if err := p.Start(); err != nil {
 		log.Fatal(err)
 	}
 }
 
+func initialize() (tea.Model, tea.Cmd) {
+	return Model(5), nil
+}
+
 // Update is called when messages are recived. The idea is that you inspect
 // the message and update the model (or send back a new one) accordingly. You
 // can also return a commmand, which is a function that peforms I/O and

examples/views/main.go

@@ -28,7 +28,7 @@ type frameMsg struct{}
 
 func main() {
 	p := tea.NewProgram(
-		Model{0, false, 10, 0, 0, false},
+		initialize,
 		update,
 		view,
 		[]tea.Sub{tick, frame},
@@ -38,6 +38,12 @@ func main() {
 	}
 }
 
+// INIT
+
+func initialize() (tea.Model, tea.Cmd) {
+	return Model{0, false, 10, 0, 0, false}, nil
+}
+
 // SUBSCRIPTIONS
 
 func tick(model tea.Model) tea.Msg {

tea.go

@@ -22,6 +22,10 @@ type Cmd func() Msg
 // Sub is an event subscription. If it returns nil it's considered a no-op.
 type Sub func(Model) Msg
 
+// Init is the first function that will be called. It returns your initial
+// model and runs an optional command
+type Init func() (Model, Cmd)
+
 // Update is called when a message is received. It may update the model and/or
 // send a command.
 type Update func(Msg, Model) (Model, Cmd)
@@ -31,7 +35,7 @@ type View func(Model) string
 
 // Program is a terminal user interface
 type Program struct {
-	model         Model
+	init          Init
 	update        Update
 	view          View
 	subscriptions []Sub
@@ -64,9 +68,9 @@ func Quit() Msg {
 type quitMsg struct{}
 
 // NewProgram creates a new Program
-func NewProgram(model Model, update Update, view View, subs []Sub) *Program {
+func NewProgram(init Init, update Update, view View, subs []Sub) *Program {
 	return &Program{
-		model:         model,
+		init:          init,
 		update:        update,
 		view:          view,
 		subscriptions: subs,
@@ -76,7 +80,7 @@ func NewProgram(model Model, update Update, view View, subs []Sub) *Program {
 // Start initializes the program
 func (p *Program) Start() error {
 	var (
-		model = p.model
+		model Model
 		cmd   Cmd
 		cmds  = make(chan Cmd)
 		msgs  = make(chan Msg)
@@ -90,13 +94,21 @@ func (p *Program) Start() error {
 
 	p.rw = tty
 	tty.SetRaw()
+	hideCursor()
 	defer func() {
 		showCursor()
 		tty.Restore()
 	}()
 
+	// Initialize program
+	model, _ = p.init()
+	if cmd != nil {
+		go func() {
+			cmds <- cmd
+		}()
+	}
+
 	// Render initial view
-	hideCursor()
 	p.render(model)
 
 	// Subscribe to user input. We could move this out of here and offer it
@@ -115,7 +127,7 @@ func (p *Program) Start() error {
 			for _, sub := range p.subscriptions {
 				go func(s Sub) {
 					for {
-						msgs <- s(p.model)
+						msgs <- s(model)
 					}
 				}(sub)
 			}
@@ -148,9 +160,9 @@ func (p *Program) Start() error {
 			}
 
 			model, cmd = p.update(msg, model)
+			log.Println(model)
 			cmds <- cmd // process command (if any)
 			p.render(model)
-			p.model = model
 		}
 	}
 }