Package io.vavr
Interface CheckedFunction0<R>
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- Type Parameters:
R
- return type of the function
- All Superinterfaces:
java.io.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 java.io.Serializable
Represents a function with no arguments.
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Field Summary
Fields Modifier and Type Field Description static long
serialVersionUID
The serial version uid.
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Method Summary
Modifier and Type Method 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 CheckedFunction1after
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 givenpartialFunction
into a total function that returns anOption
result.static <R> Function0<Try<R>>
liftTry(CheckedFunction0<? extends R> partialFunction)
Lifts the givenpartialFunction
into a total function that returns anTry
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 givenCheckedFunction0<? extends R>
toCheckedFunction0<R>
static <R> CheckedFunction0<R>
of(CheckedFunction0<R> methodReference)
default Function0<R>
recover(java.util.function.Function<? super java.lang.Throwable,? extends java.util.function.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 fromrecover
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.
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Field Detail
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serialVersionUID
static final long serialVersionUID
The serial version uid.- See Also:
- Constant Field Values
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Method Detail
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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
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of
static <R> CheckedFunction0<R> of(CheckedFunction0<R> methodReference)
Creates aCheckedFunction0
based on 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
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lift
static <R> Function0<Option<R>> lift(CheckedFunction0<? extends R> partialFunction)
Lifts the givenpartialFunction
into a total function that returns anOption
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 returnsSome(result)
if the function is defined for the given arguments, andNone
otherwise.
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liftTry
static <R> Function0<Try<R>> liftTry(CheckedFunction0<? extends R> partialFunction)
Lifts the givenpartialFunction
into a total function that returns anTry
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 returnsSuccess(result)
if the function is defined for the given arguments, andFailure(throwable)
otherwise.
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narrow
static <R> CheckedFunction0<R> narrow(CheckedFunction0<? extends R> f)
Narrows the givenCheckedFunction0<? extends R>
toCheckedFunction0<R>
- Type Parameters:
R
- return type- Parameters:
f
- ACheckedFunction0
- Returns:
- the given
f
instance as narrowed typeCheckedFunction0<R>
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apply
R apply() throws java.lang.Throwable
Applies this function to no arguments and returns the result.- Returns:
- the result of function application
- Throws:
java.lang.Throwable
- if something goes wrong applying this function to the given arguments
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arity
default int arity()
Returns the number of function arguments.- Returns:
- an int value >= 0
- See Also:
- Arity
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curried
default CheckedFunction0<R> curried()
Returns a curried version of this function.- Returns:
- a curried function equivalent to this.
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tupled
default CheckedFunction1<Tuple0,R> tupled()
Returns a tupled version of this function.- Returns:
- a tupled function equivalent to this.
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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.
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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.
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isMemoized
default boolean isMemoized()
Checks if this function is memoizing (= caching) computed values.- Returns:
- true, if this function is memoizing, false otherwise
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recover
default Function0<R> recover(java.util.function.Function<? super java.lang.Throwable,? extends java.util.function.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 fromrecover
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:
java.lang.NullPointerException
- if recover is null
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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
.
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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 CheckedFunction1after
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:
java.lang.NullPointerException
- if after is null
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