Monad (Javaslang Pure 2.0.0 API)

Type Parameters:

M - Type M<?> of a monadic instance, which is covered by this Monad

T - component type of this monad

All Superinterfaces:

Functor<T>
```
public interface Monad<M extends Kind1<M,?>,T>
extends Functor<T>
```
Defines a Monad by generalizing the flatMap function.
A Monad is a Functor with a flatMap method that satisfies the Monad laws, also known as the three control laws:
Let
- A, B, C be types
- unit: A -> Monad<A> a constructor
- f: A -> Monad<B>, g: B -> Monad<C> functions
- a be an object of type A
- m be an object of type Monad<A>
Then all instances of the Monad interface should obey the three control laws:
- Left identity: unit(a).flatMap(f) ≡ f a
- Right identity: m.flatMap(unit) ≡ m
- Associativity: m.flatMap(f).flatMap(g) ≡ m.flatMap(x -> f.apply(x).flatMap(g))
To read further about monads in Java please refer to What's Wrong in Java 8, Part IV: Monads.
Since:

1.1.0

Author:

Daniel Dietrich

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`Monad.Lifted1<T,R>` Represents a function `T -> R` lifted to `M<T> -> M<R>`.
`static interface`	`Monad.Lifted2<T1,T2,R>` Represents a function `(T1, T2) -> R` lifted to `(M<T1>, M<T2>) -> M<R>`.
`static interface`	`Monad.Lifted3<T1,T2,T3,R>` Represents a function `(T1, T2, T3) -> R` lifted to `(M<T1>, M<T2>, M<T3>) -> M<R>`.
`static interface`	`Monad.Lifted4<T1,T2,T3,T4,R>` Represents a function `(T1, T2, T3, T4) -> R` lifted to `(M<T1>, M<T2>, M<T3>, M<T4>) -> M<R>`.
`static interface`	`Monad.Lifted5<T1,T2,T3,T4,T5,R>` Represents a function `(T1, T2, T3, T4, T5) -> R` lifted to `(M<T1>, M<T2>, M<T3>, M<T4>, M<T5>) -> M<R>`.
`static interface`	`Monad.Lifted6<T1,T2,T3,T4,T5,T6,R>` Represents a function `(T1, T2, T3, T4, T5, T6) -> R` lifted to `(M<T1>, M<T2>, M<T3>, M<T4>, M<T5>, M<T6>) -> M<R>`.
`static interface`	`Monad.Lifted7<T1,T2,T3,T4,T5,T6,T7,R>` Represents a function `(T1, T2, T3, T4, T5, T6, T7) -> R` lifted to `(M<T1>, M<T2>, M<T3>, M<T4>, M<T5>, M<T6>, M<T7>) -> M<R>`.
`static interface`	`Monad.Lifted8<T1,T2,T3,T4,T5,T6,T7,T8,R>` Represents a function `(T1, T2, T3, T4, T5, T6, T7, T8) -> R` lifted to `(M<T1>, M<T2>, M<T3>, M<T4>, M<T5>, M<T6>, M<T7>, M<T8>) -> M<R>`.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`<U> Monad<M,U>`	`flatMap(Function<? super T,? extends Monad<M,U>> mapper)` FlatMaps this Monad to a new Monad with different component type.
`static <T1,T2,R> Monad.Lifted2<T1,T2,R>`	`lift(BiFunction<? super T1,? super T2,? extends R> f)` Lifts a `BiFunction` to a higher `Lifted2` function that operates on Monads.
`static <T,R> Monad.Lifted1<T,R>`	`lift(Function<? super T,? extends R> f)` Lifts a `Function` to a higher `Lifted1` function that operates on Monads.
`static <T1,T2,T3,R> Monad.Lifted3<T1,T2,T3,R>`	`lift(Function3<? super T1,? super T2,? super T3,? extends R> f)` Lifts a `Function3` to a higher `Lifted3` function that operates on Monads.
`static <T1,T2,T3,T4,R> Monad.Lifted4<T1,T2,T3,T4,R>`	`lift(Function4<? super T1,? super T2,? super T3,? super T4,? extends R> f)` Lifts a `Function4` to a higher `Lifted4` function that operates on Monads.
`static <T1,T2,T3,T4,T5,R> Monad.Lifted5<T1,T2,T3,T4,T5,R>`	`lift(Function5<? super T1,? super T2,? super T3,? super T4,? super T5,? extends R> f)` Lifts a `Function5` to a higher `Lifted5` function that operates on Monads.
`static <T1,T2,T3,T4,T5,T6,R> Monad.Lifted6<T1,T2,T3,T4,T5,T6,R>`	`lift(Function6<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? extends R> f)` Lifts a `Function6` to a higher `Lifted6` function that operates on Monads.
`static <T1,T2,T3,T4,T5,T6,T7,R> Monad.Lifted7<T1,T2,T3,T4,T5,T6,T7,R>`	`lift(Function7<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? extends R> f)` Lifts a `Function7` to a higher `Lifted7` function that operates on Monads.
`static <T1,T2,T3,T4,T5,T6,T7,T8,R> Monad.Lifted8<T1,T2,T3,T4,T5,T6,T7,T8,R>`	`lift(Function8<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? extends R> f)` Lifts a `Function8` to a higher `Lifted8` function that operates on Monads.
`<U> Monad<M,U>`	`map(Function<? super T,? extends U> mapper)` Applies a function `f` to the components of this Functor.
`Kind1<M,T>`	`narrow()` Pulls the monadic instance of type M<?> out of this Monad view.
`static <T> Monad<List<?>,T>`	`of(List<T> list)`

- Method Detail
  - flatMap
```
<U> Monad<M,U> flatMap(Function<? super T,? extends Monad<M,U>> mapper)
```
    FlatMaps this Monad to a new Monad with different component type.
    FlatMap is the sequence operation for functions and behaves like the imperative ;.
    If the previous results are needed, flatMap cascades:
```
 
 m1().flatMap(result1 ->
      m2(result1).flatMap(result2 ->
          m3(result1, result2).flatMap(result3 ->
              ...
          )
      )
 );
 
 
```
    If only the last result is needed, flatMap may be used sequentially:
```
 
 m1().flatMap(this::m2)
     .flatMap(this::m3)
     .flatMap(...);
 
 
```
    Type Parameters:
    
    U - Component type of the mapped Monad
    
    Parameters:
    
    mapper - A mapper
    
    Returns:
    
    a mapped Monad
    
    Throws:
    
    NullPointerException - if mapper is null
  - map
```
<U> Monad<M,U> map(Function<? super T,? extends U> mapper)
```
    Description copied from interface: Functor
    
    Applies a function f to the components of this Functor.
    
    Specified by:
    
    map in interface Functor<T>
    
    Type Parameters:
    
    U - 1st component type of the resulting Functor
    
    Parameters:
    
    mapper - a Function which maps the component of this Functor
    
    Returns:
    
    a new Functor
  - narrow
```
Kind1<M,T> narrow()
```
    Pulls the monadic instance of type M<?> out of this Monad view. This instance can be safely casted to type M<T>.
    
    Returns:
    
    the monadic instance wrapped by this Monad
  - of
```
static <T> Monad<List<?>,T> of(List<T> list)
```
  - lift
```
static <T,R> Monad.Lifted1<T,R> lift(Function<? super T,? extends R> f)
```
    Lifts a Function to a higher Lifted1 function that operates on Monads.
    
    Type Parameters:
    
    T - 1st argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function
    
    Returns:
    
    a new Lifted1 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,R> Monad.Lifted2<T1,T2,R> lift(BiFunction<? super T1,? super T2,? extends R> f)
```
    Lifts a BiFunction to a higher Lifted2 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a BiFunction
    
    Returns:
    
    a new Lifted2 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,R> Monad.Lifted3<T1,T2,T3,R> lift(Function3<? super T1,? super T2,? super T3,? extends R> f)
```
    Lifts a Function3 to a higher Lifted3 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function3
    
    Returns:
    
    a new Lifted3 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,T4,R> Monad.Lifted4<T1,T2,T3,T4,R> lift(Function4<? super T1,? super T2,? super T3,? super T4,? extends R> f)
```
    Lifts a Function4 to a higher Lifted4 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    T4 - 4th argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function4
    
    Returns:
    
    a new Lifted4 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,T4,T5,R> Monad.Lifted5<T1,T2,T3,T4,T5,R> lift(Function5<? super T1,? super T2,? super T3,? super T4,? super T5,? extends R> f)
```
    Lifts a Function5 to a higher Lifted5 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    T4 - 4th argument type of f
    
    T5 - 5th argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function5
    
    Returns:
    
    a new Lifted5 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,T4,T5,T6,R> Monad.Lifted6<T1,T2,T3,T4,T5,T6,R> lift(Function6<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? extends R> f)
```
    Lifts a Function6 to a higher Lifted6 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    T4 - 4th argument type of f
    
    T5 - 5th argument type of f
    
    T6 - 6th argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function6
    
    Returns:
    
    a new Lifted6 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,T4,T5,T6,T7,R> Monad.Lifted7<T1,T2,T3,T4,T5,T6,T7,R> lift(Function7<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? extends R> f)
```
    Lifts a Function7 to a higher Lifted7 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    T4 - 4th argument type of f
    
    T5 - 5th argument type of f
    
    T6 - 6th argument type of f
    
    T7 - 7th argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function7
    
    Returns:
    
    a new Lifted7 function that lifts the given function f in a layer that operates on monads.
  - lift
```
static <T1,T2,T3,T4,T5,T6,T7,T8,R> Monad.Lifted8<T1,T2,T3,T4,T5,T6,T7,T8,R> lift(Function8<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? extends R> f)
```
    Lifts a Function8 to a higher Lifted8 function that operates on Monads.
    
    Type Parameters:
    
    T1 - 1st argument type of f
    
    T2 - 2nd argument type of f
    
    T3 - 3rd argument type of f
    
    T4 - 4th argument type of f
    
    T5 - 5th argument type of f
    
    T6 - 6th argument type of f
    
    T7 - 7th argument type of f
    
    T8 - 8th argument type of f
    
    R - result type of f
    
    Parameters:
    
    f - a Function8
    
    Returns:
    
    a new Lifted8 function that lifts the given function f in a layer that operates on monads.

Interface Monad<M extends Kind1<M,?>,T>

Nested Class Summary

Method Summary

Method Detail

flatMap

map

narrow

of

lift

lift

lift

lift

lift

lift

lift

lift