dimensional: Statically checked physical dimensions, using Type Families and Data Kinds.

[ bsd3, library, math, physics ] [ Propose Tags ]

Dimensional is a library providing data types for performing arithmetic with physical quantities and units. Information about the physical dimensions of the quantities and units is embedded in their types and the validity of operations is verified by the type checker at compile time. The boxing and unboxing of numerical values as quantities is done by multiplication and division with units. The library is designed to, as far as is practical, enforce/encourage best practices of unit usage. Version 1 of the dimensional package differs from earlier version in that the dimension tracking is implemented using Closed Type Families and Data Kinds rather than functional dependencies. This enables a number of features, including improved support for unit names and quantities with statically-unknown dimensions. Requires GHC 7.8 or later.

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Versions [RSS] [faq] 0.7, 0.7.1, 0.7.2, 0.7.3, 0.8,,, 0.9, 0.10, 0.10.1,,, 0.10.2, 0.12, 0.12.1,, 0.12.2, 0.12.3, 0.13,,,,,,,, 1.1, 1.2, 1.3, 1.4
Change log CHANGELOG.md
Dependencies base (>=4.7 && <4.9), deepseq (>=1.3), exact-pi (>= && <0.5), numtype-dk (>=0.5 && <1.1), vector (>=0.10) [details]
License BSD-3-Clause
Copyright Bjorn Buckwalter 2006-2015
Author Bjorn Buckwalter
Maintainer bjorn@buckwalter.se
Revised Revision 1 made by HerbertValerioRiedel at 2019-02-09T18:06:30Z
Category Math, Physics
Home page https://github.com/bjornbm/dimensional-dk/
Source repo head: git clone https://github.com/bjornbm/dimensional-dk/
Uploaded by dmcclean at 2015-11-24T14:17:12Z
Distributions Debian:1.1, LTSHaskell:1.4, NixOS:1.4, Stackage:1.4
Downloads 23370 total (150 in the last 30 days)
Rating 2.5 (votes: 5) [estimated by Bayesian average]
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2015-11-24 [all 2 reports]




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This library provides statically-checked dimensional arithmetic for physical quantities, using the 7 SI base dimensions.

Data kinds and closed type families provide a flexible, safe, and discoverable implementation that leads to largely self-documenting client code.

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Simply importing Numeric.Units.Dimensional.Prelude provides access to dimensional arithmetic opertors, SI units and other common units accepted for use with the SI, and convenient aliases for quantities with commonly used dimensions.

The Unit d a type represents a unit with dimension d, whose conversion factor to the coherent SI base unit of the corresponding dimension is represented by a value of type a. a is commonly chosen to be Double, but can be any Floating type. Where possible, support is also provided for Fractional or Num values.

Similarly, the Quantity d a type represents a quantity with dimension d, whose numeric value is of type a. Aliases allow the use of, e.g., Length Double to mean Quantity DLength Double. A complete list of available aliases is given in the haddock documentation for the Numeric.Units.Dimensional.Quantities.

{-# LANGUAGE NoImplicitPrelude #-}

import Numeric.Units.Dimensional.Prelude
import Numeric.Units.Dimensional.NonSI (gee)

radiusOfEarth :: Length Double
radiusOfEarth = 6371 *~ kilo meter

massOfEarth :: Mass Double
massOfEarth = 5.97e24 *~ kilo gram

g :: GravitationalParameter Double
g = 6.67384e-11 *~ (meter^pos3 * (kilo gram)^neg1 * second^neg2)

gravitationalFieldStrength :: Mass a -> Length a -> Acceleration a
gravitationalFieldStrength m r = g * m / r^pos2

approximateAccelerationDueToGravityOnEarth = gravitationalFieldStrength massOfEarth radiusOfEarth

differenceFromStandardValue = approximateAccelerationDueToGravityOnEarth /~ gee


For project information (issues, updates, wiki, examples) see: https://github.com/bjornbm/dimensional-dk