Function1 (vavr 1.0.0-alpha-4 API)

Type Parameters:

T1 - argument 1 of the function

R - return type of the function

All Superinterfaces:

java.util.function.Function<T1,R>, java.io.Serializable

All Known Subinterfaces:

API.Match.Case<T,R>, API.Match.Pattern<T,R>, IndexedSeq<T>, LinearSeq<T>, Map<K,V>, Multimap<K,V>, PartialFunction<T,R>, Seq<T>, SortedMap<K,V>, SortedMultimap<K,V>

All Known Implementing Classes:

API.Match.Case0, API.Match.Case1, API.Match.Case2, API.Match.Case3, API.Match.Case4, API.Match.Case5, API.Match.Case6, API.Match.Case7, API.Match.Case8, API.Match.Pattern0, API.Match.Pattern1, API.Match.Pattern2, API.Match.Pattern3, API.Match.Pattern4, API.Match.Pattern5, API.Match.Pattern6, API.Match.Pattern7, API.Match.Pattern8, Array, CharSeq, HashMap, HashMultimap, LinkedHashMap, LinkedHashMultimap, List, List.Cons, List.Nil, Queue, Stream, Stream.Cons, Stream.Empty, TreeMap, TreeMultimap, Vector

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 Function1<T1,R>
extends java.io.Serializable, java.util.function.Function<T1,R>
```
Represents a function with one argument.

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> Function1<T1,V>`	`andThen(java.util.function.Function<? super R,? extends V> after)` Returns a composed function that first applies this Function1 to the given argument and then applies Function `after` to the result.
`R`	`apply(T1 t1)` Applies this function to one argument and returns the result.
`default int`	`arity()` Returns the number of function arguments.
`default <V> Function1<V,R>`	`compose(java.util.function.Function<? super V,? extends T1> before)` Returns a composed function that first applies the Function `before` the given argument and then applies this Function1 to the result.
`static <T1,R> Function1<T1,R>`	`constant(R value)` Returns a function that always returns the constant value that you give in parameter.
`default Function1<T1,R>`	`curried()` Returns a curried version of this function.
`static <T> Function1<T,T>`	`identity()` Returns the identity Function1, i.e.
`default boolean`	`isMemoized()` Checks if this function is memoizing (= caching) computed values.
`static <T1,R> Function1<T1,Option<R>>`	`lift(java.util.function.Function<? super T1,? extends R> partialFunction)` Lifts the given `partialFunction` into a total function that returns an `Option` result.
`static <T1,R> Function1<T1,Try<R>>`	`liftTry(java.util.function.Function<? super T1,? extends R> partialFunction)` Lifts the given `partialFunction` into a total function that returns an `Try` result.
`default Function1<T1,R>`	`memoized()` Returns a memoizing version of this function, which computes the return value for given arguments only one time.
`static <T1,R> Function1<T1,R>`	`narrow(Function1<? super T1,? extends R> f)` Narrows the given `Function1<? super T1, ? extends R>` to `Function1<T1, R>`
`static <T1,R> Function1<T1,R>`	`of(Function1<T1,R> methodReference)` Creates a `Function1` based on method reference lambda expression Examples (w.l.o.g.
`default PartialFunction<T1,R>`	`partial(java.util.function.Predicate<? super T1> isDefinedAt)` Converts this `Function1` to a `PartialFunction` by adding an `isDefinedAt` condition.
`default Function1<T1,R>`	`reversed()` Returns a reversed version of this function.
`default Function1<Tuple1<T1>,R>`	`tupled()` Returns a tupled version of this function.

- Field Detail
  - serialVersionUID
```
static final long serialVersionUID
```
    The serial version uid.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - constant
```
static <T1,R> Function1<T1,R> constant(R value)
```
    Returns a function that always returns the constant value that you give in parameter.
    
    Type Parameters:
    
    T1 - generic parameter type 1 of the resulting function
    
    R - the result type
    
    Parameters:
    
    value - the value to be returned
    
    Returns:
    
    a function always returning the given value
  - of
```
static <T1,R> Function1<T1,R> of(Function1<T1,R> methodReference)
```
    Creates a Function1 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
    
    T1 - 1st argument
    
    Parameters:
    
    methodReference - (typically) a method reference, e.g. Type::method
    
    Returns:
    
    a Function1
  - lift
```
static <T1,R> Function1<T1,Option<R>> lift(java.util.function.Function<? super T1,? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Option result.
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    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 <T1,R> Function1<T1,Try<R>> liftTry(java.util.function.Function<? super T1,? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Try result.
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    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 <T1,R> Function1<T1,R> narrow(Function1<? super T1,? extends R> f)
```
    Narrows the given Function1<? super T1, ? extends R> to Function1<T1, R>
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    Parameters:
    
    f - A Function1
    
    Returns:
    
    the given f instance as narrowed type Function1<T1, R>
  - identity
```
static <T> Function1<T,T> identity()
```
    Returns the identity Function1, i.e. the function that returns its input.
    
    Specified by:
    
    identity in interface java.util.function.Function<T1,R>
    
    Type Parameters:
    
    T - argument type (and return type) of the identity function
    
    Returns:
    
    the identity Function1
  - apply
```
R apply(T1 t1)
```
    Applies this function to one argument and returns the result.
    
    Specified by:
    
    apply in interface java.util.function.Function<T1,R>
    
    Parameters:
    
    t1 - argument 1
    
    Returns:
    
    the result of function application
  - arity
```
default int arity()
```
    Returns the number of function arguments.
    
    Returns:
    
    an int value >= 0
    
    See Also:
    
    Arity
  - curried
```
default Function1<T1,R> curried()
```
    Returns a curried version of this function.
    
    Returns:
    
    a curried function equivalent to this.
  - tupled
```
default Function1<Tuple1<T1>,R> tupled()
```
    Returns a tupled version of this function.
    
    Returns:
    
    a tupled function equivalent to this.
  - reversed
```
default Function1<T1,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 Function1<T1,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
  - partial
```
default PartialFunction<T1,R> partial(java.util.function.Predicate<? super T1> isDefinedAt)
```
    Converts this Function1 to a PartialFunction by adding an isDefinedAt condition.
    
    Parameters:
    
    isDefinedAt - a predicate that states if an element is in the domain of the returned PartialFunction.
    
    Returns:
    
    a new PartialFunction that has the same behavior like this function but is defined only for those elements that make it through the given Predicate
    
    Throws:
    
    java.lang.NullPointerException - if isDefinedAt is null
  - andThen
```
default <V> Function1<T1,V> andThen(java.util.function.Function<? super R,? extends V> after)
```
    Returns a composed function that first applies this Function1 to the given argument and then applies Function after to the result.
    
    Specified by:
    
    andThen in interface java.util.function.Function<T1,R>
    
    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
  - compose
```
default <V> Function1<V,R> compose(java.util.function.Function<? super V,? extends T1> before)
```
    Returns a composed function that first applies the Function before the given argument and then applies this Function1 to the result.
    
    Specified by:
    
    compose in interface java.util.function.Function<T1,R>
    
    Type Parameters:
    
    V - argument type of before
    
    Parameters:
    
    before - the function applied before this
    
    Returns:
    
    a function composed of before and this
    
    Throws:
    
    java.lang.NullPointerException - if before is null

Interface Function1<T1,R>

Field Summary

Method Summary

Field Detail

serialVersionUID

Method Detail

constant

of

lift

liftTry

narrow

identity

apply

arity

curried

tupled

reversed

memoized

isMemoized

partial

andThen

compose