Hi everyone,

I would like to announce the initial release of event-lang, an
experimental Racket library that simplifies the creation of complex
synchronizable events.


Event-lang provides a primitive expression lifting form,

  > (pure 123)

some event combinators,

  > (sync (fmap + (pure 1) (pure 2)))
  > (sync (app (pure +) (pure 1) (pure 2)))
  > (sync (bind (pure 1) (pure 2) (λ xs (pure (apply + xs)))))

and a collection of event-friendly alternatives to base Racket forms
and functions.

  > (sync
      ([x (pure 1)]
       [y (pure 2)])
      (pure (list x y))))
  '(1 2)

Composite events make progress by synchronizing constituent events,
either concurrently or in a predictable sequence. Synchronization
results can be ordered as specified,

  > (let ([t0 (current-inexact-milliseconds)])
      (define (now) (- (current-inexact-milliseconds) t0))
        (pure (cons 1 (now)))
        (pure (cons 2 (now)))
        (pure (cons 3 (now))))))
  '(1 . 0.200927734375)
  '(2 . 0.14990234375)
  '(3 . 0.178955078125)

or as completed.

  > (let ([t0 (current-inexact-milliseconds)])
      (define (now) (- (current-inexact-milliseconds) t0))
        (pure (cons 1 (now)))
        (pure (cons 2 (now)))
        (pure (cons 3 (now))))))
  '(2 . 0.0771484375)
  '(3 . 0.093017578125)
  '(1 . 0.123046875)

The project has three outstanding objectives:

1. Provide a sophisticated lifting form

  to simplify usage of the provided constructs. The event/event module
  contains a first approximation. Its construction was tedious and
  error prone, so I commented out the docs.

2. Provide a full-blown #lang event/racket/base

  for producing whole modules of events and event constructors from
  ordinary Racket code in a principled manner.

3. Provide support for static analysis of synchronization behaviors.

  Event programming in Racket is a curious form of meta-programming,
  and a few simple compile-time checks could reduce cognitive

This pre-release is a request for feedback in anticipation of a
production-ready version 1.0. I would like to round out the base
collection and devise a comprehensive testing plan, with a stretch
goal of re-introducing the sophisticated lifting form. At the moment,
I'm using event-lang daily and adding base constructs as needed. Feel
free to do the same or request your favorites.

Please take a look and let me know what you think.


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