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.
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