Module

Neon.Data

Package: purescript-neon
Repository: tfausak/purescript-neon

Data types and constructors.

#exception Source

exception :: String -> Error

Creates an exception with the given message.

exception "example"

Re-exports from Control.Monad.Eff.Exception

#Error

data Error :: Type

The type of JavaScript errors

Instances

Show Error

Re-exports from Data.List

#List

data List a

Constructors

Nil
Cons a (List a)

Instances

(Show a) => Show (List a)
(Eq a) => Eq (List a)
Eq1 List
(Ord a) => Ord (List a)
Ord1 List
Semigroup (List a)
Monoid (List a)
Functor List
FunctorWithIndex Int List
Foldable List
FoldableWithIndex Int List
Unfoldable List
Traversable List
TraversableWithIndex Int List
Apply List
Applicative List
Bind List
Monad List
Alt List
Plus List
Alternative List
MonadZero List
MonadPlus List
Extend List

Re-exports from Data.Maybe

#Maybe Source

data Maybe a

The Maybe type is used to represent optional values and can be seen as something like a type-safe null, where Nothing is null and Just x is the non-null value x.

Constructors

Nothing
Just a

Instances

Functor Maybe
The Functor instance allows functions to transform the contents of a Just with the <$> operator:
```
f <$> Just x == Just (f x)
```
Nothing values are left untouched:
```
f <$> Nothing == Nothing
```
Apply Maybe
The Apply instance allows functions contained within a Just to transform a value contained within a Just using the apply operator:
```
Just f <*> Just x == Just (f x)
```
Nothing values are left untouched:
```
Just f <*> Nothing == Nothing
Nothing <*> Just x == Nothing
```
Combining Functor's <$> with Apply's <*> can be used transform a pure function to take Maybe-typed arguments so f :: a -> b -> c becomes f :: Maybe a -> Maybe b -> Maybe c:
```
f <$> Just x <*> Just y == Just (f x y)
```
The Nothing-preserving behaviour of both operators means the result of an expression like the above but where any one of the values is Nothing means the whole result becomes Nothing also:
```
f <$> Nothing <*> Just y == Nothing
f <$> Just x <*> Nothing == Nothing
f <$> Nothing <*> Nothing == Nothing
```
Applicative Maybe
The Applicative instance enables lifting of values into Maybe with the pure or return function (return is an alias for pure):
```
pure x :: Maybe _ == Just x
return x :: Maybe _ == Just x
```
Combining Functor's <$> with Apply's <*> and Applicative's pure can be used to pass a mixture of Maybe and non-Maybe typed values to a function that does not usually expect them, by using pure for any value that is not already Maybe typed:
```
f <$> Just x <*> pure y == Just (f x y)
```
Even though pure = Just it is recommended to use pure in situations like this as it allows the choice of Applicative to be changed later without having to go through and replace Just with a new constructor.
Alt Maybe
The Alt instance allows for a choice to be made between two Maybe values with the <|> operator, where the first Just encountered is taken.
```
Just x <|> Just y == Just x
Nothing <|> Just y == Just y
Nothing <|> Nothing == Nothing
```
Plus Maybe
The Plus instance provides a default Maybe value:
```
empty :: Maybe _ == Nothing
```
Alternative Maybe
The Alternative instance guarantees that there are both Applicative and Plus instances for Maybe.
Bind Maybe
The Bind instance allows sequencing of Maybe values and functions that return a Maybe by using the >>= operator:
```
Just x >>= f = f x
Nothing >>= f = Nothing
```
Monad Maybe
The Monad instance guarantees that there are both Applicative and Bind instances for Maybe. This also enables the do syntactic sugar:
```
do
  x' <- x
  y' <- y
  pure (f x' y')
```
Which is equivalent to:
```
x >>= (\x' -> y >>= (\y' -> pure (f x' y')))
```
MonadZero Maybe
Extend Maybe
The Extend instance allows sequencing of Maybe values and functions that accept a Maybe a and return a non-Maybe result using the <<= operator.
```
f <<= Nothing = Nothing
f <<= Just x = Just (f x)
```
Invariant Maybe
(Semigroup a) => Semigroup (Maybe a)
The Semigroup instance enables use of the operator <> on Maybe values whenever there is a Semigroup instance for the type the Maybe contains. The exact behaviour of <> depends on the "inner" Semigroup instance, but generally captures the notion of appending or combining things.
```
Just x <> Just y = Just (x <> y)
Just x <> Nothing = Just x
Nothing <> Just y = Just y
Nothing <> Nothing = Nothing
```
(Semigroup a) => Monoid (Maybe a)
(Eq a) => Eq (Maybe a)
Eq1 Maybe
(Ord a) => Ord (Maybe a)
Ord1 Maybe
(Bounded a) => Bounded (Maybe a)
(Show a) => Show (Maybe a)
The Show instance allows Maybe values to be rendered as a string with show whenever there is an Show instance for the type the Maybe contains.

Re-exports from Data.Tuple

#Tuple Source

data Tuple a b

A simple product type for wrapping a pair of component values.

Constructors

Tuple a b

Instances

(Show a, Show b) => Show (Tuple a b)
Allows Tuples to be rendered as a string with show whenever there are Show instances for both component types.
(Eq a, Eq b) => Eq (Tuple a b)
(Eq a) => Eq1 (Tuple a)
(Ord a, Ord b) => Ord (Tuple a b)
(Ord a) => Ord1 (Tuple a)
(Bounded a, Bounded b) => Bounded (Tuple a b)
Semigroupoid Tuple
(Semigroup a, Semigroup b) => Semigroup (Tuple a b)
The Semigroup instance enables use of the associative operator <> on Tuples whenever there are Semigroup instances for the component types. The <> operator is applied pairwise, so:
```
(Tuple a1 b1) <> (Tuple a2 b2) = Tuple (a1 <> a2) (b1 <> b2)
```
(Monoid a, Monoid b) => Monoid (Tuple a b)
(Semiring a, Semiring b) => Semiring (Tuple a b)
(Ring a, Ring b) => Ring (Tuple a b)
(CommutativeRing a, CommutativeRing b) => CommutativeRing (Tuple a b)
(HeytingAlgebra a, HeytingAlgebra b) => HeytingAlgebra (Tuple a b)
(BooleanAlgebra a, BooleanAlgebra b) => BooleanAlgebra (Tuple a b)
Functor (Tuple a)
The Functor instance allows functions to transform the contents of a Tuple with the <$> operator, applying the function to the second component, so:
```
f <$> (Tuple x y) = Tuple x (f y)
```
Invariant (Tuple a)
Bifunctor Tuple
(Semigroup a) => Apply (Tuple a)
The Functor instance allows functions to transform the contents of a Tuple with the <*> operator whenever there is a Semigroup instance for the fst component, so:
```
(Tuple a1 f) <*> (Tuple a2 x) == Tuple (a1 <> a2) (f x)
```
Biapply Tuple
(Monoid a) => Applicative (Tuple a)
Biapplicative Tuple
(Semigroup a) => Bind (Tuple a)
(Monoid a) => Monad (Tuple a)
Extend (Tuple a)
Comonad (Tuple a)
(Lazy a, Lazy b) => Lazy (Tuple a b)
Foldable (Tuple a)
Bifoldable Tuple
Traversable (Tuple a)
Bitraversable Tuple
(TypeEquals a Unit) => Distributive (Tuple a)

Re-exports from Prelude

#Unit

data Unit :: Type

The Unit type has a single inhabitant, called unit. It represents values with no computational content.

Unit is often used, wrapped in a monadic type constructor, as the return type of a computation where only the effects are important.

Instances

Show Unit

#Ordering

data Ordering

The Ordering data type represents the three possible outcomes of comparing two values:

LT - The first value is less than the second. GT - The first value is greater than the second. EQ - The first value is equal to the second.

Constructors

LT
GT
EQ

Instances

Eq Ordering
Semigroup Ordering
Show Ordering

#unit

unit :: Unit

unit is the sole inhabitant of the Unit type.

Re-exports from Type.Proxy

#Proxy Source

data Proxy a

Value proxy for kind Type types.

Constructors

Proxy