GenFRP
GenFRP is a library that allows for programming in elixir using the Functional Reactive Programming method.
This is a way to store and dispatch information that is very readable and extensible.
The idea is as follows:
- Your FRP module contains
use GenFRP, initial_state: some_useful_starting_state
. (some_useful_starting_state
can be anything you wish, of course) - It implements the
update(state, event) :: state
function. - It implements the
render(state, last_rendered_state) :: any
function.
update
is called whenever an event is sent to the GenFRP process by using GenFRP.send_event(frp_pid, whatever_you_want_to_send)
.
render
is called whenever you want to know its current state (in some representation format that is useful for the outside world, i.e. rendered).
GenFRP uses a very simple caching mechanism to ensure that render
is only invoked when the internal state has changed since its last invocation.
Here is a very simple example (which can be found as GenFRP.Example.Map
as well)
defmodule GenFRP.Example.Map do
use GenFRP
def init, do: %{}
def update(state, [{key, val}]) do
Map.put(state, key, val)
end
def update(state, event) do
IO.puts "Unrecognized event passed to `#{inspect(__MODULE__)}.update/2`: #{event}"
end
@doc """
Returns the key-value pairs as strings, separated over multiple lines, in alphabetical order.
"""
def render(state, last_rendered_state) do
Enum.map(state, fn {key, val} ->
"`#{key}`: `#{val}`"
end)
end
Enum.join("\n")
end
This can be used as follows:
{:ok, pid} = GenFRP.start_link(GenFRP.Example.Map)
# ... maybe some other code here...
GenFRP.send_event(pid, {:foo, :bar})
# ... maybe some more code here...
GenFRP.send_event(pid, {:baz, 42})
# ... maybe yet some other code here...
GenFRP.render(pid)
"`foo`: `bar`
`baz`: `42`
"
Installation
The package can be installed
by adding gen_frp
to your list of dependencies in mix.exs
:
def deps do
[{:gen_frp, "~> 0.5.0"}]
end
Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/gen_frp.
Changelog
- 0.5.0 Changed the way the initial state works to
init/0
, to follow the naming convention that GenServer et al. already use. Also, documentation was improved. - 0.1.0 Initial released version.