defmodule Kino do
@moduledoc ~S'''
Client-driven interactive widgets for Livebook.
Kino is the library used by Livebook to render rich and interactive
outputs directly from your Elixir code.
## Built-in kinos
Kino renders any data structure that implements the `Kino.Render`
protocol, falling back to the `Kernel.inspect/2` representation
whenever an implementation is not available. The data structures
supported by Kino out of the box are:
### Kino.DataTable
`Kino.DataTable` implements a data table output for user-provided
tabular data:
data = [
%{id: 1, name: "Elixir", website: "https://elixir-lang.org"},
%{id: 2, name: "Erlang", website: "https://www.erlang.org"}
]
Kino.DataTable.new(data)
### Kino.ETS
`Kino.ETS` implements a data table output for ETS tables in the
system:
tid = :ets.new(:users, [:set, :public])
Kino.ETS.new(tid)
### Kino.Image
`Kino.Image` wraps binary image content and can be used to render
raw images of any given format:
content = File.read!("/path/to/image.jpeg")
Kino.Image.new(content, "image/jpeg")
### Kino.Markdown
`Kino.Markdown` renders Markdown content, in case you need richer text:
Kino.Markdown.new("""
# Example
A regular Markdown file.
## Code
```elixir
"Elixir" |> String.graphemes() |> Enum.frequencies()
```
## Table
| ID | Name | Website |
| -- | ------ | ----------------------- |
| 1 | Elixir | https://elixir-lang.org |
| 2 | Erlang | https://www.erlang.org |
""")
### Kino.Text
`Kino.Text` renders plain text content. It is similar to `Kino.Markdown`,
however doesn't interpret any markup.
Kino.Text.new("Hello!")
### Kino.Mermaid
`Kino.Mermaid` renders Mermaid graphs:
Kino.Mermaid.new("""
graph TD;
A-->B;
A-->C;
B-->D;
C-->D;
""")
### Kino.Frame
`Kino.Frame` is a placeholder for static outputs that can
be dynamically updated.
frame = Kino.Frame.new() |> Kino.render()
for i <- 1..100 do
Kino.Frame.render(frame, i)
Process.sleep(50)
end
Also see `Kino.animate/3`.
### Kino.Tree
`Kino.Tree` displays arbitrarily nested data structure as a
tree view.
data = Process.info(self())
Kino.Tree.new(data)
### Kino.HTML
`Kino.HTML` displays arbitrary static HTML.
Kino.HTML.new("""
<h3>Look!</h3>
<p>I wrote this HTML from <strong>Kino</strong>!</p>
""")
### User interactions
`Kino.Input` and `Kino.Control` provide a set of widgets for
entering data and capturing user events. See the respective
module documentation for examples.
### All others
All other data structures are rendered as text using Elixir's
`Kernel.inspect/2`.
## Custom kinos
Kino makes it possible to define custom JavaScript powered
kinos, see `Kino.JS` and `Kino.JS.Live` for more details.
> #### Packaging {: .info}
>
> When publishing custom kinos and smart cells, please consider
> the following guidelines:
>
> * prefix package name with `kino_`, usually followed by the
> name of the integration, such as `kino_vega_lite`, `kino_ecto`
>
> * namespace all modules under `KinoExample`, not `Kino.Example`.
> Note that official packages maintained by the Livebook team
> expose public APIs under `Kino.`, because they are essentially
> direct extensions of `Kino` and we make sure no conflicting
> modules exist. Unofficial packages should follow the usual
> Elixir conventions with respect to module names
>
'''
import Kernel, except: [inspect: 1]
require Logger
@type nothing :: :"do not show this result in output"
@doc """
Renders the given term as cell output.
This effectively allows any Livebook cell to have multiple
evaluation results.
"""
@spec render(term()) :: term()
def render(term) do
output = Kino.Render.to_livebook(term)
Kino.Bridge.put_output(output)
term
end
@doc """
Inspects the given term as cell output.
This works essentially the same as `IO.inspect/2`, except it
always produces colored text and respects the configuration
set with `configure/1`.
Opposite to `render/1`, it does not attempt to render the given
term as a kino.
"""
@spec inspect(term(), keyword()) :: term()
def inspect(term, opts \\ []) do
label = if label = opts[:label], do: "#{label}: ", else: ""
{:text, text} = Kino.Output.inspect(term, opts)
output = {:text, label <> text}
Kino.Bridge.put_output(output)
term
end
@doc """
Configures Kino.
The supported options are:
* `:inspect`
They are discussed individually in the sections below.
## Inspect
A keyword list containing inspect options used for printing
usual evaluation results. Defaults to pretty formatting with
a limit of 50 entries.
To show more entries, you configure a higher limit:
Kino.configure(inspect: [limit: 200])
You can also show all entries by setting the limit to `:infinity`,
but keep in mind that for large data structures it is memory-expensive
and is not an advised configuration in this case. Instead prefer
the use of `IO.inspect/2` with `:infinity` limit when needed.
See `Inspect.Opts` for the full list of options.
"""
@spec configure(keyword()) :: :ok
def configure(options) do
Kino.Config.configure(options)
end
@doc ~S"""
Renders a kino that periodically calls the given function
to render a new result.
The callback receives a stream element and should return a term
to be rendered.
This function uses `Kino.Frame` as the underlying kino.
It returns nothing (a non-printable result).
## Examples
An animation is created by turning a stream of values into
subsequent animation frames:
Stream.interval(100)
|> Stream.take(100)
|> Kino.animate(fn i ->
Kino.Markdown.new("**Iteration: `#{i}`**")
end)
Alternatively an integer may be passed as a shorthand for
`Stream.interval/1`:
# Render new Markdown every 100ms
Kino.animate(100, fn i ->
Kino.Markdown.new("**Iteration: `#{i}`**")
end)
"""
@spec animate(Enumerable.t() | pos_integer(), (term() -> any())) :: nothing()
def animate(stream_or_interval_ms, fun) when is_function(fun, 1) do
animate(stream_or_interval_ms, nil, fn item, nil ->
{:cont, fun.(item), nil}
end)
end
@doc ~S"""
A stateful version of `animate/2`.
The callback receives a stream element and the accumulated state
and it should return either of:
* `{:cont, term_to_render, state}` - the continue
* `:halt` - to no longer schedule callback evaluation
## Examples
This function is primarily useful to consume `Kino.Control` events:
button = Kino.Control.button("Click")
button
|> Kino.Control.stream()
|> Kino.animate(0, fn _event, counter ->
new_counter = counter + 1
md = Kino.Markdown.new("**Clicks: `#{new_counter}`**")
{:cont, md, new_counter}
end)
"""
@spec animate(
Enumerable.t() | pos_integer(),
state,
(term(), state -> {:cont, term(), state} | :halt)
) :: nothing()
when state: term()
def animate(stream_or_interval_ms, state, fun)
def animate(interval_ms, state, fun) when is_integer(interval_ms) and is_function(fun, 2) do
animate(Stream.interval(interval_ms), state, fun)
end
def animate(stream, state, fun) when is_function(fun, 2) do
frame = Kino.Frame.new() |> Kino.render()
listen(stream, state, fn item, state ->
case safe_apply(fun, [item, state], "Kino.animate") do
{:ok, {:cont, term, state}} ->
Kino.Frame.render(frame, term)
{:cont, state}
{:ok, :halt} ->
:halt
{:error, _, _} ->
{:cont, state}
end
end)
nothing()
end
@doc ~S"""
Consumes a stream with `fun` without blocking execution.
Note that events are processed by `fun` sequentially. If you want
to process them concurrently, use `async_listen/2`.
## Examples
This function is primarily useful to consume `Kino.Control` events:
Kino.Control.button("Greet")
|> Kino.listen(fn event -> IO.inspect(event) end)
You can also merge multiple controls into a single stream. For example,
in order to merge them and tag each with a distinct event:
button = Kino.Control.button("Hello")
input = Kino.Input.checkbox("Check")
stream = Kino.Control.tagged_stream([hello: button, check: input])
Kino.listen(stream, fn
{:hello, event} -> ...
{:check, event} -> ...
end)
Any other stream works as well:
Stream.interval(100)
|> Stream.take(10)
|> Kino.listen(fn i -> IO.puts("Ping #{i}") end)
Finally, an integer may be passed as a shorthand for `Stream.interval/1`:
Kino.listen(100, fn i -> IO.puts("Ping #{i}") end)
"""
@spec listen(Enumerable.t() | pos_integer(), (term() -> any())) :: :ok
def listen(stream_or_interval_ms, fun)
def listen(interval_ms, fun) when is_integer(interval_ms) and is_function(fun, 1) do
listen(Stream.interval(interval_ms), fun)
end
def listen(stream, fun) when is_function(fun, 1) do
async(fn -> Enum.each(stream, &safe_apply(fun, [&1], "Kino.listen")) end)
end
@doc ~S"""
A stateful version of `listen/2`.
The callback should return either of:
* `{:cont, state}` - the continue
* `:halt` - to stop listening
## Examples
button = Kino.Control.button("Click")
Kino.listen(button, 0, fn _event, counter ->
new_counter = counter + 1
IO.puts("Clicks: #{new_counter}")
{:cont, new_counter}
end)
"""
@spec listen(
Enumerable.t() | pos_integer(),
state,
(term(), state -> {:cont, state} | :halt)
) :: :ok
when state: term()
def listen(stream_or_interval_ms, state, fun)
def listen(interval_ms, state, fun) when is_integer(interval_ms) and is_function(fun, 2) do
listen(Stream.interval(interval_ms), state, fun)
end
def listen(stream, state, fun) when is_function(fun, 2) do
async(fn ->
Enum.reduce_while(stream, state, fn item, state ->
case safe_apply(fun, [item, state], "Kino.listen") do
{:ok, {:cont, state}} -> {:cont, state}
{:ok, :halt} -> {:halt, state}
{:error, _, _} -> {:cont, state}
end
end)
end)
end
defp safe_apply(fun, args, context) do
try do
{:ok, apply(fun, args)}
catch
kind, error ->
Logger.error(
"#{context} with #{Kernel.inspect(fun)} failed with reason:\n\n" <>
Exception.format(kind, error, __STACKTRACE__)
)
{:error, kind, error}
end
end
defp async(fun) do
{:ok, _pid} =
Kino.start_child(%{
id: Task,
start: {Kino.Terminator, :start_task, [self(), fun]},
restart: :temporary
})
:ok
end
@doc """
Same as `listen/2`, except each event is processed concurrently.
"""
@spec async_listen(Enumerable.t() | pos_integer(), (term() -> any())) :: :ok
def async_listen(stream_or_interval_ms, fun)
def async_listen(interval_ms, fun) when is_integer(interval_ms) and is_function(fun, 1) do
async_listen(Stream.interval(interval_ms), fun)
end
def async_listen(stream, fun) when is_function(fun, 1) do
async(fn ->
# For organization purposes we start all tasks under a separate
# supervisor and only that supervisor is started with Kino.start_child/1
start_fun = fn ->
{:ok, task_supervisor} = start_child(Task.Supervisor)
task_supervisor
end
reducer = fn event, task_supervisor ->
{[{event, task_supervisor}], task_supervisor}
end
after_fun = fn task_supervisor ->
for {_, pid, _, _} <- DynamicSupervisor.which_children(task_supervisor),
is_pid(pid),
Process.alive?(pid) do
ref = Process.monitor(pid)
receive do
{:DOWN, ^ref, _, _, _} -> :ok
end
end
DynamicSupervisor.terminate_child(Kino.DynamicSupervisor, task_supervisor)
end
stream
|> Stream.transform(start_fun, reducer, after_fun)
|> Enum.each(fn {event, task_supervisor} ->
Task.Supervisor.start_child(task_supervisor, fn ->
safe_apply(fun, [event], "Kino.async_listen")
end)
end)
end)
end
@doc """
Returns a special value that results in no visible output.
"""
@spec nothing() :: nothing()
def nothing() do
:"do not show this result in output"
end
@doc """
Starts a process under the Kino supervisor.
The process is automatically terminated when the current process
terminates or the current cell reevaluates.
If you want to terminate the started process, use
`terminate_child/1`. If you terminate the process manually,
the Kino supervisor might restart it if the child's `:restart`
strategy says so.
> #### Nested start {: .warning}
>
> It is not possible to use `start_child/1` while initializing
> another process started this way. In other words, you generally
> cannot call `start_child/1` inside callbacks such as `c:GenServer.init/1`
> or `c:Kino.JS.Live.init/2`. If you do that, starting the process
> will block forever.
>
> Note that creating many kinos uses `start_child/1` underneath,
> hence the same restriction applies to starting those. See
> `c:Kino.JS.Live.init/2` for more details.
"""
@spec start_child(
Supervisor.child_spec()
| {module(), term()}
| module()
) :: DynamicSupervisor.on_start_child()
def start_child(child_spec) do
%{start: start} = child_spec = Supervisor.child_spec(child_spec, [])
parent = self()
gl = Process.group_leader()
child_spec = %{child_spec | start: {Kino.Terminator, :start_child, [start, parent, gl]}}
DynamicSupervisor.start_child(Kino.DynamicSupervisor, child_spec)
end
@doc """
Terminates a child started with `start_child/1`.
Returns `:ok` if the child was found and terminated, or
`{:error, :not_found}` if the child was not found.
"""
@doc since: "0.9.1"
@spec terminate_child(pid()) :: :ok | {:error, :not_found}
def terminate_child(pid) when is_pid(pid) do
DynamicSupervisor.terminate_child(Kino.DynamicSupervisor, pid)
end
end
