# Data.Field

- Package
- purescript-prelude
- Repository
- purescript/purescript-prelude

### #Field Source

`class (EuclideanRing a) <= Field a `

The `Field`

class is for types that are commutative fields.

Instances must satisfy the following law in addition to the
`EuclideanRing`

laws:

- Non-zero multiplicative inverse:
`a `mod` b = zero`

for all`a`

and`b`

The `Unit`

instance is provided for backwards compatibility, but it is
not law-abiding, because `Unit`

does not obey the `EuclideanRing`

laws.
This instance will be removed in a future release.

#### Instances

## Re-exports from **Data.**CommutativeRing

### #CommutativeRing Source

`class (Ring a) <= CommutativeRing a `

The `CommutativeRing`

class is for rings where multiplication is
commutative.

Instances must satisfy the following law in addition to the `Ring`

laws:

- Commutative multiplication:
`a * b = b * a`

#### Instances

## Re-exports from **Data.**EuclideanRing

### #EuclideanRing Source

`class (CommutativeRing a) <= EuclideanRing a where`

The `EuclideanRing`

class is for commutative rings that support division.
The mathematical structure this class is based on is sometimes also called
a *Euclidean domain*.

Instances must satisfy the following laws in addition to the `Ring`

laws:

- Integral domain:
`one /= zero`

, and if`a`

and`b`

are both nonzero then so is their product`a * b`

- Euclidean function
`degree`

:- Nonnegativity: For all nonzero
`a`

,`degree a >= 0`

- Quotient/remainder: For all
`a`

and`b`

, where`b`

is nonzero, let`q = a / b`

and`r = a `mod` b`

; then`a = q*b + r`

, and also either`r = zero`

or`degree r < degree b`

- Nonnegativity: For all nonzero
- Submultiplicative euclidean function:
- For all nonzero
`a`

and`b`

,`degree a <= degree (a * b)`

- For all nonzero

The behaviour of division by `zero`

is unconstrained by these laws,
meaning that individual instances are free to choose how to behave in this
case. Similarly, there are no restrictions on what the result of
`degree zero`

is; it doesn't make sense to ask for `degree zero`

in the
same way that it doesn't make sense to divide by `zero`

, so again,
individual instances may choose how to handle this case.

For any `EuclideanRing`

which is also a `Field`

, one valid choice
for `degree`

is simply `const 1`

. In fact, unless there's a specific
reason not to, `Field`

types should normally use this definition of
`degree`

.

The `Unit`

instance is provided for backwards compatibility, but it is
not law-abiding, because `Unit`

fails to form an integral domain. This
instance will be removed in a future release.

#### Members

#### Instances

### #lcm Source

`lcm :: forall a. Eq a => EuclideanRing a => a -> a -> a`

The *least common multiple* of two values.

### #gcd Source

`gcd :: forall a. Eq a => EuclideanRing a => a -> a -> a`

The *greatest common divisor* of two values.

## Re-exports from **Data.**Ring

### #Ring Source

## Re-exports from **Data.**Semiring

### #Semiring Source

`class Semiring a where`

The `Semiring`

class is for types that support an addition and
multiplication operation.

Instances must satisfy the following laws:

- Commutative monoid under addition:
- Associativity:
`(a + b) + c = a + (b + c)`

- Identity:
`zero + a = a + zero = a`

- Commutative:
`a + b = b + a`

- Associativity:
- Monoid under multiplication:
- Associativity:
`(a * b) * c = a * (b * c)`

- Identity:
`one * a = a * one = a`

- Associativity:
- Multiplication distributes over addition:
- Left distributivity:
`a * (b + c) = (a * b) + (a * c)`

- Right distributivity:
`(a + b) * c = (a * c) + (b * c)`

- Left distributivity:
- Annihilation:
`zero * a = a * zero = zero`

**Note:** The `Number`

and `Int`

types are not fully law abiding
members of this class hierarchy due to the potential for arithmetic
overflows, and in the case of `Number`

, the presence of `NaN`

and
`Infinity`

values. The behaviour is unspecified in these cases.

#### Members

#### Instances

- Modules
- Control.
Applicative - Control.
Apply - Control.
Bind - Control.
Category - Control.
Monad - Control.
Semigroupoid - Data.
Boolean - Data.
BooleanAlgebra - Data.
Bounded - Data.
CommutativeRing - Data.
Eq - Data.
EuclideanRing - Data.
Field - Data.
Function - Data.
Functor - Data.
HeytingAlgebra - Data.
NaturalTransformation - Data.
Ord - Data.
Ord. Unsafe - Data.
Ordering - Data.
Ring - Data.
Semigroup - Data.
Semiring - Data.
Show - Data.
Unit - Data.
Void - Prelude