AsyncRattus: An asynchronous modal FRP language
This library implements the Async Rattus programming language as an embedded DSL. To this end the library provides a GHC plugin that checks the stricter typing rules of Async Rattus. What follows is a brief introduction to the language and its usage. A more detailed introduction can be found in this paper.
Async Rattus is a functional reactive programming (FRP) language that uses modal types to express temporal dependencies. In return the language will guarantee that programs are productive (in each computation step, the program makes progress), causal (output depends only on current and earlier input), and have no space leaks (programs do not implicitly retain memory over time).
The modal type constructor O
(pronounced "later") is
used to express the passage of time at the type
level. Intuitively speaking, a value of type O a
represents a computation that will produce a value of type
a
in the next time step. Additionally, the language also
features the Box
modal type constructor. A value of type
Box a
is a time-independent computation that can be
executed at any time to produce a value of type a
.
For example, the type of signals is defined as
data Sig a = a ::: (O (Sig a))
So the current value of the signal is available now, but
its future state is only available in the next time
step. Writing a map
function for this type of streams,
requires us to use the Box
modality:
map :: Box (a -> b) -> Sig a -> Sig b map f (x ::: xs) = unbox f x ::: delay (map f (adv xs))
This makes sure that the function f
that we give to
map
is available at any time in the future.
The core of the language is defined in the module
AsyncRattus.Primitives. Note that the operations on O
and Box
have non-standard typing rules. Therefore, this
library provides a compiler plugin that checks these
non-standard typing rules. To write Async Rattus programs,
you must enable this plugin via the GHC option
-fplugin=AsyncRattus.Plugin
, e.g. by including the following
line in the source file:
{-# OPTIONS -fplugin=AsyncRattus.Plugin #-}
Below is a minimal Async Rattus program using the AsyncRattus.Signal module for programming with signals:
{-# OPTIONS -fplugin=AsyncRattus.Plugin #-} import AsyncRattus import AsyncRattus.Signal sums :: Sig Int -> Sig Int sums = scan (box (+)) 0
The source code of the AsyncRattus.Signal module provides more examples on how to program in Async Rattus. An example project using Async Rattus can be found here.
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Versions [RSS] | 0.1, 0.1.0.1, 0.1.0.2, 0.1.0.3, 0.2, 0.2.0.1, 0.2.0.2 |
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Change log | CHANGELOG.md |
Dependencies | base (>=4.16 && <5), containers (>=0.6.5 && <0.8), ghc (>=9.2 && <9.9), ghc-boot (>=9.2 && <9.9), hashtables (>=1.3.1 && <1.4), simple-affine-space (>=0.2.1 && <0.3), transformers (>=0.5.6 && <0.7) [details] |
License | BSD-3-Clause |
Copyright | Copyright (C) 2023 Emil Houlborg, Gregers Rørdam, Patrick Bahr |
Author | Emil Houlborg, Gregers Rørdam, Patrick Bahr |
Maintainer | Patrick Bahr <paba@itu.dk> |
Category | FRP |
Home page | https://github.com/pa-ba/AsyncRattus/ |
Bug tracker | https://github.com/pa-ba/AsyncRattus/issues |
Uploaded | by PatrickBahr at 2024-10-03T08:45:14Z |
Distributions | NixOS:0.2.0.1 |
Downloads | 245 total (17 in the last 30 days) |
Rating | 2.0 (votes: 1) [estimated by Bayesian average] |
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Status | Docs available [build log] Last success reported on 2024-10-03 [all 1 reports] |