bidule 0.2.0

Ultra simple Functional Reactive Programming, made with stuff, things, device, thingumajig, etc.
Documentation 
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extern crate bidule;

use bidule::*;

#[test]
fn frp() {
  use std::cell::RefCell;
  use std::rc::Rc;

  enum Button {
    Push,
  }

  enum Counter {
    Increment,
    Decrement,
    Reset,
  }

  let minus_button: Stream<Button> = Stream::new();
  let plus_button: Stream<Button> = Stream::new();
  let reset_button: Stream<Button> = Stream::new();

  let minus = minus_button.map(|_| Counter::Decrement);
  let plus = plus_button.map(|_| Counter::Increment);
  let reset = reset_button.map(|_| Counter::Reset);

  let label = minus
    .merge(&plus)
    .merge(&reset)
    .fold(0, |x, sig| match *sig {
      Counter::Increment => x + 1,
      Counter::Decrement => x - 1,
      Counter::Reset => 0,
    })
    .filter(|x| x % 2 == 0); // get only even counters

  // FIXME: this part is ugly, we need to find a better API for “inspecting” streams
  let counter = Rc::new(RefCell::new(0));
  let counter_ = counter.clone();
  label.observe(move |x| *counter_.borrow_mut() = *x);

  assert_eq!(*counter.borrow(), 0);

  minus_button.send(&Button::Push);
  assert_eq!(*counter.borrow(), 0); // not -1 because -1 is odd

  minus_button.send(&Button::Push);
  assert_eq!(*counter.borrow(), -2);

  plus_button.send(&Button::Push);
  assert_eq!(*counter.borrow(), -2); // not -1, it’s odd

  reset_button.send(&Button::Push);
  assert_eq!(*counter.borrow(), 0);
}

#[test]
fn mutual_recursion() {
  use std::cell::RefCell;
  use std::rc::Rc;

  #[derive(Clone, Debug, Eq, PartialEq)]
  enum Button {
    ChangeLabel(String),
    Push,
  }

  fn f(sig: &Button) -> Option<Button> {
    match *sig {
      Button::Push => Some(Button::ChangeLabel("foo".to_owned())),
      _ => None,
    }
  }

  let (x, y) = Stream::entangled(f, f);

  let x_ref = Rc::new(RefCell::new(Button::Push));
  let x_ref_ = x_ref.clone();

  let y_ref = Rc::new(RefCell::new(Button::Push));
  let y_ref_ = y_ref.clone();

  x.observe(move |a| *x_ref_.borrow_mut() = a.clone());
  y.observe(move |a| *y_ref_.borrow_mut() = a.clone());

  assert_eq!(*x_ref.borrow(), Button::Push);
  assert_eq!(*y_ref.borrow(), Button::Push);

  x.send(&Button::Push);
  assert_eq!(*x_ref.borrow(), Button::Push);
  assert_eq!(*y_ref.borrow(), Button::ChangeLabel("foo".to_owned()));

  y.send(&Button::Push);
  assert_eq!(*x_ref.borrow(), Button::ChangeLabel("foo".to_owned()));
  assert_eq!(*y_ref.borrow(), Button::Push);
}

#[test]
fn zip() {
  use std::cell::RefCell;
  use std::rc::Rc;

  let x = Stream::new();
  let y = Stream::new();
  let z = x.zip(&y);

  let z_ref = Rc::new(RefCell::new(Either::Right(3)));
  let z_ref_ = z_ref.clone();

  z.observe(move |a| *z_ref_.borrow_mut() = a.clone());

  assert_eq!(*z_ref.borrow(), Either::Right(3));

  x.send(&false);
  assert_eq!(*z_ref.borrow(), Either::Left(false));

  y.send(&42);
  assert_eq!(*z_ref.borrow(), Either::Right(42));
}

#[test]
fn unzip() {
  use std::cell::RefCell;
  use std::rc::Rc;

  let tuple = Stream::new();
  let (x, y) = tuple.unzip();

  let x_ref = Rc::new(RefCell::new(0));
  let x_ref_ = x_ref.clone();

  let y_ref = Rc::new(RefCell::new(0));
  let y_ref_ = y_ref.clone();

  x.observe(move |a| *x_ref_.borrow_mut() = *a);
  y.observe(move |a| *y_ref_.borrow_mut() = *a);

  assert_eq!(*x_ref.borrow(), 0);
  assert_eq!(*y_ref.borrow(), 0);

  tuple.send(&Either::Left(34));
  tuple.send(&Either::Right(13));
  assert_eq!(*x_ref.borrow(), 34);
  assert_eq!(*y_ref.borrow(), 13);
}