mealy: Mealy machines for processing time-series and ordered data.
mealy reimagines statistics as a mealy machine processing data with some form of order such as time-series data. The Mealy, with the help of a decay function specifying the relative weights of recent values versus older value, can be treated as a compression or summary of the data stream into 'current state.'
Mealies are highly polymorphic, situated at a busy crossroad of theory and practice, and lend themselves to ergonmic, compact and realistic representations of a wide range of online phenomena.
Usage
>>>import Mealy
>>>fold ((,) <$> ma 0.9 <*> std 0.9) [1..100](91.00265621044142,9.472822805289121)
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- mealy-0.5.1.0.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)
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| Versions [RSS] | 0.0.1, 0.0.2, 0.0.3, 0.1.0, 0.2.0, 0.3.0, 0.4.0, 0.4.1, 0.4.2, 0.4.3, 0.4.4, 0.4.4.1, 0.4.5.0, 0.5.0.0, 0.5.0.1, 0.5.1.0, 0.5.1.1 |
|---|---|
| Change log | ChangeLog.md |
| Dependencies | adjunctions (>=4.0 && <4.5), base (>=4.14 && <5), containers (>=0.6 && <0.9), harpie (>=0.1 && <0.2), harpie-numhask (>=0.1 && <0.2), mealy, mwc-probability (>=2.3.1 && <2.4), numhask (>=0.11 && <0.14), optparse-applicative (>=0.17 && <0.20), perf (>=0.14 && <0.15), primitive (>=0.7.2 && <0.10), profunctors (>=5.6.2 && <5.7), tdigest (>=0.2.1 && <0.4), text (>=1.2 && <2.2), vector (>=0.12.3 && <0.14), vector-algorithms (>=0.8.0 && <0.10) [details] |
| Tested with | ghc ==9.10.3, ghc ==9.12.2, ghc ==9.14.1 |
| License | BSD-3-Clause |
| Copyright | Tony Day (c) 2013 |
| Author | Tony Day |
| Maintainer | tonyday567@gmail.com |
| Uploaded | by tonyday567 at 2026-01-10T13:09:27Z |
| Category | algorithm |
| Home page | https://github.com/tonyday567/mealy#readme |
| Bug tracker | https://github.com/tonyday567/mealy/issues |
| Source repo | head: git clone https://github.com/tonyday567/mealy |
| Distributions | LTSHaskell:0.5.0.1, NixOS:0.5.0.1 |
| Reverse Dependencies | 3 direct, 2 indirect [details] |
| Executables | mealy-perf |
| Downloads | 1401 total (47 in the last 30 days) |
| Rating | (no votes yet) [estimated by Bayesian average] |
| Your Rating | |
| Status | Docs not available [build log] All reported builds failed as of 2026-01-10 [all 2 reports] |
Readme for mealy-0.5.1.0
[back to package description]mealy
A 'Mealy' is a triple of functions
- (a -> b) inject: Convert (initial) input into the (initial) state type.
- (b -> a -> b) step: Update state given prior state and (new) input.
- (c -> b) extract: Convert state to the output type.
A sum, for example, looks like M id (+) id where the first id is the initial injection and the second id is the covariant extraction.
This library provides support for computing statistics (such as an average or a standard deviation) as current state within a mealy context.
Usage
Usage is to supply a decay function representing the relative weights of recent values versus older ones, in the manner of exponentially-weighted averages. The library attempts to be polymorphic in the statistic which can be combined in applicative style.
import Prelude
import Data.Mealy
fold ((,) <$> ma 0.9 <*> std 0.9) [1..100::Double]
(91.00265621044142,9.472822805289121)