[Haskell-cafe] ANN: Elerea 1.1

Patai Gergely patai_gergely at fastmail.fm
Thu Nov 26 08:39:36 EST 2009


Hello all,

Elerea is a simple pull-based FRP library, which allows you to do
stream-oriented programming using a primarily applicative style. Unlike
traditional stream-based languages, streams (which I call 'signals' in
the library) are first-class entities. I uploaded a new version with an
experimental branch that reimplements the original idea in a completely
different way:

- without unsafePerformIO (although with some restructuring it could be
used to make the interface 'more applicative') or existential types
- signals are Monad instances, so you can use do notation to sample them
- for the same reason the 'sampler' combinator is gone; you can use join
instead, which is also well-behaved in comparison (i.e. the output of
signals doesn't depend any more on how you observe them)
- since the library didn't build on the time step being a Double in any
way, I relaxed its type (see the Param branch)
- the semantics is cleaned up somewhat (I plan to elaborate on this
point later in a blog post, but until then you can check the Simple
branch for a general idea)

Gergely

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