CheckedFunction0 (Vavr 0.10.0 API)

Type Parameters:

R - return type of the function

All Superinterfaces:

Serializable

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
```
@FunctionalInterface
public interface CheckedFunction0<R>
extends Serializable
```
Represents a function with no arguments.

Author:

Daniel Dietrich

Field Summary

Fields
Modifier and Type Field and Description

static long serialVersionUID
The serial version uid.

Fields
Modifier and Type	Field and Description
`static long`	`serialVersionUID` The serial version uid.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`default <V> CheckedFunction0<V>`	`andThen(CheckedFunction1<? super R,? extends V> after)` Returns a composed function that first applies this CheckedFunction0 to the given argument and then applies CheckedFunction1 `after` to the result.
`R`	`apply()` Applies this function to no arguments and returns the result.
`default int`	`arity()` Returns the number of function arguments.
`static <R> CheckedFunction0<R>`	`constant(R value)` Returns a function that always returns the constant value that you give in parameter.
`default CheckedFunction0<R>`	`curried()` Returns a curried version of this function.
`default boolean`	`isMemoized()` Checks if this function is memoizing (= caching) computed values.
`static <R> Function0<Option<R>>`	`lift(CheckedFunction0<? extends R> partialFunction)` Lifts the given `partialFunction` into a total function that returns an `Option` result.
`static <R> Function0<Try<R>>`	`liftTry(CheckedFunction0<? extends R> partialFunction)` Lifts the given `partialFunction` into a total function that returns an `Try` result.
`default CheckedFunction0<R>`	`memoized()` Returns a memoizing version of this function, which computes the return value for given arguments only one time.
`static <R> CheckedFunction0<R>`	`narrow(CheckedFunction0<? extends R> f)` Narrows the given `CheckedFunction0<? extends R>` to `CheckedFunction0<R>`
`static <R> CheckedFunction0<R>`	`of(CheckedFunction0<R> methodReference)` Creates a `CheckedFunction0` based on method reference lambda expression Examples (w.l.o.g.
`default Function0<R>`	`recover(Function<? super Throwable,? extends Supplier<? extends R>> recover)` Return a composed function that first applies this CheckedFunction0 to the given arguments and in case of throwable try to get value from `recover` function with same arguments and throwable information.
`default CheckedFunction0<R>`	`reversed()` Returns a reversed version of this function.
`default CheckedFunction1<Tuple0,R>`	`tupled()` Returns a tupled version of this function.
`default Function0<R>`	`unchecked()` Returns an unchecked function that will sneaky throw if an exceptions occurs when applying the function.

- Field Detail
  - serialVersionUID
```
static final long serialVersionUID
```
    The serial version uid.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - constant
```
static <R> CheckedFunction0<R> constant(R value)
```
    Returns a function that always returns the constant value that you give in parameter.
    
    Type Parameters:
    
    R - the result type
    
    Parameters:
    
    value - the value to be returned
    
    Returns:
    
    a function always returning the given value
  - of
```
static <R> CheckedFunction0<R> of(CheckedFunction0<R> methodReference)
```
    Creates a CheckedFunction0 based on
    - method reference
    - lambda expression
    Examples (w.l.o.g. referring to Function1):
```
// using a lambda expression
 Function1<Integer, Integer> add1 = Function1.of(i -> i + 1);

 // using a method reference (, e.g. Integer method(Integer i) { return i + 1; })
 Function1<Integer, Integer> add2 = Function1.of(this::method);

 // using a lambda reference
 Function1<Integer, Integer> add3 = Function1.of(add1::apply);
 
```
    Caution: Reflection loses type information of lambda references.
```
// type of a lambda expression
 Type<?, ?> type1 = add1.getType(); // (Integer) -> Integer

 // type of a method reference
 Type<?, ?> type2 = add2.getType(); // (Integer) -> Integer

 // type of a lambda reference
 Type<?, ?> type3 = add3.getType(); // (Object) -> Object
 
```
    Type Parameters:
    
    R - return type
    
    Parameters:
    
    methodReference - (typically) a method reference, e.g. Type::method
    
    Returns:
    
    a CheckedFunction0
  - lift
```
static <R> Function0<Option<R>> lift(CheckedFunction0<? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Option result.
    
    Type Parameters:
    
    R - return type
    
    Parameters:
    
    partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
    
    Returns:
    
    a function that applies arguments to the given partialFunction and returns Some(result) if the function is defined for the given arguments, and None otherwise.
  - liftTry
```
static <R> Function0<Try<R>> liftTry(CheckedFunction0<? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Try result.
    
    Type Parameters:
    
    R - return type
    
    Parameters:
    
    partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
    
    Returns:
    
    a function that applies arguments to the given partialFunction and returns Success(result) if the function is defined for the given arguments, and Failure(throwable) otherwise.
  - narrow
```
static <R> CheckedFunction0<R> narrow(CheckedFunction0<? extends R> f)
```
    Narrows the given CheckedFunction0<? extends R> to CheckedFunction0<R>
    
    Type Parameters:
    
    R - return type
    
    Parameters:
    
    f - A CheckedFunction0
    
    Returns:
    
    the given f instance as narrowed type CheckedFunction0<R>
  - apply
```
R apply()
 throws Throwable
```
    Applies this function to no arguments and returns the result.
    
    Returns:
    
    the result of function application
    
    Throws:
    
    Throwable - if something goes wrong applying this function to the given arguments
  - arity
```
default int arity()
```
    Returns the number of function arguments.
    
    Returns:
    
    an int value >= 0
    
    See Also:
    
    Arity
  - curried
```
default CheckedFunction0<R> curried()
```
    Returns a curried version of this function.
    
    Returns:
    
    a curried function equivalent to this.
  - tupled
```
default CheckedFunction1<Tuple0,R> tupled()
```
    Returns a tupled version of this function.
    
    Returns:
    
    a tupled function equivalent to this.
  - reversed
```
default CheckedFunction0<R> reversed()
```
    Returns a reversed version of this function. This may be useful in a recursive context.
    
    Returns:
    
    a reversed function equivalent to this.
  - memoized
```
default CheckedFunction0<R> memoized()
```
    Returns a memoizing version of this function, which computes the return value for given arguments only one time. On subsequent calls given the same arguments the memoized value is returned.
    Please note that memoizing functions do not permit null as single argument or return value.
    
    Returns:
    
    a memoizing function equivalent to this.
  - isMemoized
```
default boolean isMemoized()
```
    Checks if this function is memoizing (= caching) computed values.
    
    Returns:
    
    true, if this function is memoizing, false otherwise
  - recover
```
default Function0<R> recover(Function<? super Throwable,? extends Supplier<? extends R>> recover)
```
    Return a composed function that first applies this CheckedFunction0 to the given arguments and in case of throwable try to get value from recover function with same arguments and throwable information.
    
    Parameters:
    
    recover - the function applied in case of throwable
    
    Returns:
    
    a function composed of this and recover
    
    Throws:
    
    NullPointerException - if recover is null
  - unchecked
```
default Function0<R> unchecked()
```
    Returns an unchecked function that will sneaky throw if an exceptions occurs when applying the function.
    
    Returns:
    
    a new Function0 that throws a Throwable.
  - andThen
```
default <V> CheckedFunction0<V> andThen(CheckedFunction1<? super R,? extends V> after)
```
    Returns a composed function that first applies this CheckedFunction0 to the given argument and then applies CheckedFunction1 after to the result.
    
    Type Parameters:
    
    V - return type of after
    
    Parameters:
    
    after - the function applied after this
    
    Returns:
    
    a function composed of this and after
    
    Throws:
    
    NullPointerException - if after is null

Interface CheckedFunction0<R>

Field Summary

Method Summary

Field Detail

serialVersionUID

Method Detail

constant

of

lift

liftTry

narrow

apply

arity

curried

tupled

reversed

memoized

isMemoized

recover

unchecked

andThen