# Boba

The fun, functional way to build terminal apps. A Go framework based on
[The Elm Architecture][elm].

⚠️  This project is a pre-release so the API is subject to change
a little. That said, we're using it in production.


## Simple example

```go
package main

// A simple program that counts down from 5 and then exits.

import (
	"fmt"
	"log"
	"time"
	"github.com/charmbracelet/boba"
)

type model int

type tickMsg time.Time

func main() {
	p := boba.NewProgram(init, update, view, subscriptions)
	if err := p.Start(); err != nil {
		log.Fatal(err)
	}
}

// Listen for messages and update the model accordingly
func update(msg boba.Msg, mdl boba.Model) (boba.Model, boba.Cmd) {
	m, _ := mdl.(model)

	switch msg.(type) {
	case tickMsg:
        m--
		if m == 0 {
			return m, boba.Quit
		}
	}
	return m, nil
}

// Render to the terminal
func view(mdl boba.Model) string {
	m, _ := mdl.(model)
	return fmt.Sprintf("Hi. This program will exit in %d seconds...\n", m)
}

// Subscribe to events
func subscriptions(_ boba.Model) boba.Subs {
    return boba.Subs{
        "tick": time.Every(time.Second, func(t time.Time) boba.Msg {
            return tickMsg(t)
        },
    }
}
```

Hungry for more? See the [other examples][examples].

[examples]: https://github.com/charmbracelet/boba/tree/master/examples


## Other Resources

* [Termenv](https://github.com/muesli/termenv): advanced ANSI style and color
  support for your terminal applications. Very useful when rendering your
  views.
* [Reflow](https://github.com/muesli/reflow): a collection of ANSI-aware text
  formatting tools. Also useful for view rendering.


## Acknowledgments

Heavily inspired by both [The Elm Architecture][elm] by Evan Czaplicki et al.
and [go-tea][gotea] by TJ Holowaychuk.

[elm]: https://guide.elm-lang.org/architecture/
[gotea]: https://github.com/tj/go-tea


## License

[MIT](https://github.com/charmbracelet/boba/raw/master/LICENSE)

***

Part of [Charm](https://charm.sh).

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