Copyright	(c) Alice Rixte 2025
License	BSD 3
Maintainer	alice.rixte@u-bordeaux.fr
Stability	unstable
Portability	non-portable (GHC extensions)
Safe Haskell	None
Language	Haskell2010

Data.Units.Base.Arithmetic

Contents

Addition
Subtraction
Multiplication
Division
Exponentiation

Description

Addition, multiplication and exponentiation of quantities. Dimension analysis is done statically via the type system.

Addition and multiplication of a quantity by a scalar

To add, multiply, divide, and so on, a quantity with a scalar , use its Fractional instance :

>>> a = Milli (Second 5)
>>> 3 * a
quantity @(Milli Second) 15

Warning: These instances are provided because they are convenient, but be careful ! This means that you can write:

>>> Second 2 * Second 3
Second 6

which does not respect dimension analysis: the multiplication of two time quantities should be of dimension T² and here it has dimension T.

Some of the operators proposed here solve this problem:

>>> Second 2 .*~ Second 3
quantity @(Second .^+ 2) 6

Synopsis

(.+~) :: forall u v a. FromTo' v u a => u a -> v a -> u a
(~+.) :: FromTo' u v a => u a -> v a -> v a
(~+~) :: (DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> BaseUnitOf u a
(.-~) :: forall u v a. FromTo' v u a => u a -> v a -> u a
(~-.) :: FromTo' u v a => u a -> v a -> v a
(~-~) :: (DimEq u v, ConversionFactor v a, ConversionFactor u a) => u a -> v a -> BaseUnitOf u a
(.*.) :: (IsUnit u, IsUnit v, Num a) => u a -> v a -> (u .*. v) a
(.*~) :: forall u v a uv. (uv ~ (u .*~ v), FromTo' (u .*. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a
(~*.) :: forall u v a uv. (uv ~ (u ~*. v), FromTo' (u .*. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a
(~*~) :: (u2 ~ (BaseUnitOf u .^+ 2), IsUnit u2, DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> u2 a
(./.) :: (IsUnit u, IsUnit v, IsUnit (u ./. v), Fractional a) => u a -> v a -> (u ./. v) a
(./~) :: forall u v a uv. (uv ~ (u ./~ v), FromTo' (u ./. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a
(~/.) :: forall u v a uv. (uv ~ (u ~/. v), FromTo' (u ./. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a
(~/~) :: (DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> NoUnit a
(.^.) :: forall (n :: ZZ) proxy u a. (IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> (u .^. n) a
(~^.) :: forall (n :: ZZ) proxy u a un. (un ~ (u ~^. n), FromTo' (u .^. n) un a, IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> un a
(.^~) :: forall (n :: ZZ) proxy u a un. (un ~ (u .^~ n), FromTo' (u .^. n) un a, IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> un a
(~^~) :: forall (n :: ZZ) proxy u un a. (KnownInt n, ConversionFactor u a, un ~ (BaseUnitOf u .^. n)) => u a -> proxy n -> un a

Addition

(.+~) :: forall u v a. FromTo' v u a => u a -> v a -> u a infixr 5 Source #

Add two quantities of same dimension. The unit of the right operand is converted to the unit of the left operand

>>> Kilo (Meter 5) .+~ Meter 80
quantity @(Kilo Meter) 5.08

>>> Meter 2 .+~ Second 3
 • Cannot convert unit ‘s’ of dimension ‘T’
   to unit ‘m’ of dimension ‘L’.

(~+.) :: FromTo' u v a => u a -> v a -> v a infixr 5 Source #

Same as (.+~) but it is the left operand that is converted.

>>> Kilo (Meter 5) ~+. Meter 80
quantity @(Kilo Meter) 5080.0

(~+~) :: (DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> BaseUnitOf u a infixr 5 Source #

Add two quantities of same dimension and convert to the standard unit.

>>> Kilo (Meter 1) ~+~ Milli (Meter 150)
Meter 1000.15

Subtraction

(.-~) :: forall u v a. FromTo' v u a => u a -> v a -> u a infixr 5 Source #

Subtract two quantities of same dimension. The unit of the right operand is converted to the unit of the left operand

>>> Kilo (Meter 5) .-~ Meter 80
quantity @(Kilo Meter) 4.92

(~-.) :: FromTo' u v a => u a -> v a -> v a infixr 5 Source #

Same as (.-~) but it is the left operand that is converted.

>>> Kilo (Meter 5) ~-. Meter 80
Meter 4920.0

(~-~) :: (DimEq u v, ConversionFactor v a, ConversionFactor u a) => u a -> v a -> BaseUnitOf u a infixr 5 Source #

Subtract two quantities of same dimension and convert to the standard unit.

>>> Kilo (Meter 1) ~-~ Milli (Meter 150)
Meter 999.85

Multiplication

(.*.) :: (IsUnit u, IsUnit v, Num a) => u a -> v a -> (u .*. v) a infixr 7 Source #

Multiply two quantities.

Usage is not recommended, as this will result non standard units.

For instance:

>>> Kilo (Meter 2) .*. Milli (Meter 4)
quantity @(Kilo Meter .*. Milli Meter) 8

(.*~) :: forall u v a uv. (uv ~ (u .*~ v), FromTo' (u .*. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a infixr 7 Source #

Multiply two quantities, and tries to normalize the resulting unit, without converting to base units.

>>> Meter 2 .*~ Meter 3 .*~ Meter 4
quantity @(Meter.^+3) 24

When two multiplied units have the same dimension, the right most unit is converted to left most unit:

>>> Milli (Meter 2) .*~ Micro (Meter 3)
quantity @(Milli Meter.^+2) 6.0e-3

Derived units are not unfolded:

>>> Kilo Watt 3 .*~ Hour 5
quantity @(Kilo Watt .*. Hour) 14.999999999999998

Units are ordered, so that the result unit do not depend on the order of the computations.

>>> Meter 2 .*~ Newton 2 .*~ Kilo (Meter 2) .*~ Kilo (Gram 1)
quantity @(Newton .*. Kilo Gram .*. Meter.^+2) 8000.0

(~*.) :: forall u v a uv. (uv ~ (u ~*. v), FromTo' (u .*. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a infixr 7 Source #

Same as (.*~) but with right priority

>>> Meter 2 ~*. Meter 3 ~*. Meter 4
quantity @(Meter.^+3) 24

>>> Milli (Meter 2) ~*. Micro (Meter 3)
quantity @(Micro Meter.^+2) 6000.000000000001

(~*~) :: (u2 ~ (BaseUnitOf u .^+ 2), IsUnit u2, DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> u2 a infix 7 Source #

Multiply two quantities of the same dimension and convert both of them to the corresponding standard unity.

>>> Milli (Meter 2) ~*~ Kilo (Meter 3)
quantity @(Meter .^+ 2) 6.0

>>> Meter 2 ~*~ Second 5
• Cannot convert unit ‘m’ to unit ‘s’ because their dimensions do not match.
  Dimension of ‘m’ is: L
  Dimension of ‘s’ is: T

Division

(./.) :: (IsUnit u, IsUnit v, IsUnit (u ./. v), Fractional a) => u a -> v a -> (u ./. v) a infix 7 Source #

Multiply two quantities.

Usage is not recommended, as this will result non standard units.

For instance:

>>> Kilo (Meter 2) ./. Milli (Meter 4)
quantity @(Kilo Meter .*. Milli Meter.^-1) 0.5

(./~) :: forall u v a uv. (uv ~ (u ./~ v), FromTo' (u ./. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a infix 7 Source #

Same (.*~) but for division.

>>> Milli (Meter 3) ./~ quantity @(Meter .^+ 2) 2
quantity @(Milli Meter.^-1) 1.5e-6

(~/.) :: forall u v a uv. (uv ~ (u ~/. v), FromTo' (u ./. v) uv a, IsUnit u, IsUnit v, IsUnit uv, Num a) => u a -> v a -> uv a infix 7 Source #

Same (~/.) but with right priority

>>> Milli (Meter 3) ~/. quantity @(Meter .^+ 2) 2
quantity @(Meter.^-1) 1.5e-3

(~/~) :: (DimEq u v, ConversionFactor u a, ConversionFactor v a) => u a -> v a -> NoUnit a infix 6 Source #

Divide two quantities of same dimensions. The numerator will be converted to the denominator

Units of the same dimension are authorized only when the units are equal.

>>> Meter 4 ~/~ Kilo (Meter 1)
NoUnit 4.0e-3

Exponentiation

(.^.) :: forall (n :: ZZ) proxy u a. (IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> (u .^. n) a infix 8 Source #

Raise a quantity to a power.

This is meant to be used with Proxy

>>> Meter 2 .^. pos2
quantity @(Meter.^+2) 4.

Usage is not recommended, as this will result non standard units.

For instance:

>>> (Meter 2 .*. Centi (Meter 30)) .^. pos2
quantity @((Meter .*. Centi Meter).^+2) 3600.0

(~^.) :: forall (n :: ZZ) proxy u a un. (un ~ (u ~^. n), FromTo' (u .^. n) un a, IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> un a infix 8 Source #

Raise a quantity to a power and tries to normalize the resulting unit, without converting to base units.

>>> Meter 2 ~^. pos2
quantity @(Meter.^+2) 4.0

>>> (Meter 2 .*. Centi (Meter 30)) ~^. pos2
quantity @(Centi Meter.^+4) 3.6e7

(.^~) :: forall (n :: ZZ) proxy u a un. (un ~ (u .^~ n), FromTo' (u .^. n) un a, IsUnit u, KnownInt n, Fractional a) => u a -> proxy n -> un a infix 8 Source #

Same as (.^~) but with priority to rightmost units.

>>> Meter 2 .^~ pos2
quantity @(Meter.^+2) 4.0

>>> (Meter 2 .*. Centi (Meter 30)) ~^. pos2
quantity @(Meter.^+4) 0.36000000000000004

(~^~) :: forall (n :: ZZ) proxy u un a. (KnownInt n, ConversionFactor u a, un ~ (BaseUnitOf u .^. n)) => u a -> proxy n -> un a infix 8 Source #

Raise a quantity to a power and convert to the standard unit.

>>> Kilo (Meter 2) ~^~ neg1
quantity @(Meter .^- 1) 5.0e-4