Vavr 0.10.6 · io.vavr.collection.Foldable · APIdia, the JavaDoc alternative

Method Summary

Modifier and Type	Method and Description
public default T	Returns: a folded value fold(T A zero element to start with. zero, BiFunction<? super T, ? super T, ? extends T> A function which combines elements. combine) Folds this elements using the given associative binary operator, starting with `zero` and successively calling `combine`.
public < the type to fold over U> U	Returns: a folded value foldLeft(U A zero element to start with. zero, BiFunction<? super U, ? super T, ? extends U> A function which combines elements. combine) Folds this elements from the left, starting with `zero` and successively calling `combine`.
public < the type of the folded value U> U	Returns: a folded value foldRight(U A zero element to start with. zero, BiFunction<? super T, ? super U, ? extends U> A function which combines elements. combine) Folds this elements from the right, starting with `zero` and successively calling `combine`.
public default T	Returns: the reduced value. reduce(BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op`.
public T	Returns: the reduced value. reduceLeft(BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the left.
public Option<T>	Returns: Some of reduced value or None if the Foldable is empty. reduceLeftOption(BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the left.
public default Option<T>	Returns: Some of reduced value or None if the Foldable is empty. reduceOption(BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op`.
public T	Returns: the reduced value. reduceRight(BiFunction<? super T, ? super T, ? extends T> An operation of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the right.
public Option<T>	Returns: Some of reduced value or None. reduceRightOption(BiFunction<? super T, ? super T, ? extends T> An operation of type T op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the right.

Method Detail

fold back to summary

fold	back to summary
public default T fold(T zero, BiFunction<? super T, ? super T, ? extends T> combine) Folds this elements using the given associative binary operator, starting with `zero` and successively calling `combine`. The order in which the elements are combined is non-deterministic. The methods `fold`, `foldLeft` and `foldRight` differ in how the elements are combined: `foldLeft(Object, BiFunction)` associates to the left `foldRight(Object, BiFunction)` associates to the right `fold` takes an associative combine operation because the traversal of elements is unordered/non-deterministic. The associativity guarantees that in each case the result will be the same, it does not matter in which order the elements are combined. Generally binary operators aren't associative, i.e. the result may differ if elements are combined in a different order. We say that this Foldable and the associative combine operation form a Monoid. Example: `// = 6 Set(1, 2, 3).fold(0, (a, b) -> a + b);` Parameters zero:T A zero element to start with. combine:BiFunction<? super T, ? super T, ? extends T> A function which combines elements. Returns:T a folded value Exceptions NullPointerException: if `combine` is null

public default T fold(T zero, BiFunction<? super T, ? super T, ? extends T> combine)

Folds this elements using the given associative binary operator, starting with zero and successively calling combine. The order in which the elements are combined is non-deterministic.

The methods fold, foldLeft and foldRight differ in how the elements are combined:

foldLeft(Object, BiFunction) associates to the left
foldRight(Object, BiFunction) associates to the right
fold takes an associative combine operation because the traversal of elements is unordered/non-deterministic. The associativity guarantees that in each case the result will be the same, it does not matter in which order the elements are combined. Generally binary operators aren't associative, i.e. the result may differ if elements are combined in a different order.
We say that this Foldable and the associative combine operation form a Monoid.

Example:

 // = 6
Set(1, 2, 3).fold(0, (a, b) -> a + b);

Parameters

zero:T: A zero element to start with.
combine:BiFunction<? super T, ? super T, ? extends T>: A function which combines elements.

Returns:T

a folded value

Exceptions

NullPointerException:: if combine is null

foldLeft back to summary

foldLeft	back to summary
public <U> U foldLeft(U zero, BiFunction<? super U, ? super T, ? extends U> combine) Folds this elements from the left, starting with `zero` and successively calling `combine`. Example: `// = "cba!" List("a", "b", "c").foldLeft("!", (xs, x) -> x + xs)` Parameters <U> the type to fold over zero:U A zero element to start with. combine:BiFunction<? super U, ? super T, ? extends U> A function which combines elements. Returns:U a folded value Exceptions NullPointerException: if `combine` is null

public <U> U foldLeft(U zero, BiFunction<? super U, ? super T, ? extends U> combine)

Folds this elements from the left, starting with zero and successively calling combine.

Example:

 // = "cba!"
List("a", "b", "c").foldLeft("!", (xs, x) -> x + xs)

Parameters

<U>: the type to fold over
zero:U: A zero element to start with.
combine:BiFunction<? super U, ? super T, ? extends U>: A function which combines elements.

Returns:U

a folded value

Exceptions

NullPointerException:: if combine is null

foldRight back to summary

foldRight	back to summary
public <U> U foldRight(U zero, BiFunction<? super T, ? super U, ? extends U> combine) Folds this elements from the right, starting with `zero` and successively calling `combine`. Example: `// = "!cba" List("a", "b", "c").foldRight("!", (x, xs) -> xs + x)` Parameters <U> the type of the folded value zero:U A zero element to start with. combine:BiFunction<? super T, ? super U, ? extends U> A function which combines elements. Returns:U a folded value Exceptions NullPointerException: if `combine` is null

public <U> U foldRight(U zero, BiFunction<? super T, ? super U, ? extends U> combine)

Folds this elements from the right, starting with zero and successively calling combine.

Example:

 // = "!cba"
List("a", "b", "c").foldRight("!", (x, xs) -> xs + x)

Parameters

<U>: the type of the folded value
zero:U: A zero element to start with.
combine:BiFunction<? super T, ? super U, ? extends U>: A function which combines elements.

Returns:U

a folded value

Exceptions

NullPointerException:: if combine is null

reduce back to summary

reduce	back to summary
public default T reduce(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op`. The order of element iteration is undetermined. Parameters op:BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T Returns:T the reduced value. Exceptions NoSuchElementException: if this is empty NullPointerException: if `op` is null

public default T reduce(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op. The order of element iteration is undetermined.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: A BiFunction of type T

Returns:T

the reduced value.

Exceptions

NoSuchElementException:: if this is empty
NullPointerException:: if op is null

reduceLeft back to summary

reduceLeft	back to summary
public T reduceLeft(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the left. Parameters op:BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T Returns:T the reduced value. Exceptions NoSuchElementException: if this is empty NullPointerException: if `op` is null

public T reduceLeft(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op from the left.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: A BiFunction of type T

Returns:T

the reduced value.

Exceptions

NoSuchElementException:: if this is empty
NullPointerException:: if op is null

reduceLeftOption back to summary

reduceLeftOption	back to summary
public Option<T> reduceLeftOption(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the left. Parameters op:BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T Returns:Option<T> Some of reduced value or None if the Foldable is empty. Exceptions NullPointerException: if `op` is null

public Option<T> reduceLeftOption(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op from the left.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: A BiFunction of type T

Returns:Option<T>

Some of reduced value or None if the Foldable is empty.

Exceptions

NullPointerException:: if op is null

reduceOption back to summary

reduceOption	back to summary
public default Option<T> reduceOption(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op`. The order of element iteration is undetermined. Parameters op:BiFunction<? super T, ? super T, ? extends T> A BiFunction of type T Returns:Option<T> Some of reduced value or None if the Foldable is empty. Exceptions NullPointerException: if `op` is null

public default Option<T> reduceOption(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op. The order of element iteration is undetermined.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: A BiFunction of type T

Returns:Option<T>

Some of reduced value or None if the Foldable is empty.

Exceptions

NullPointerException:: if op is null

reduceRight back to summary

reduceRight	back to summary
public T reduceRight(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the right. Parameters op:BiFunction<? super T, ? super T, ? extends T> An operation of type T Returns:T the reduced value. Exceptions NoSuchElementException: if this is empty NullPointerException: if `op` is null

public T reduceRight(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op from the right.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: An operation of type T

Returns:T

the reduced value.

Exceptions

NoSuchElementException:: if this is empty
NullPointerException:: if op is null

reduceRightOption back to summary

reduceRightOption	back to summary
public Option<T> reduceRightOption(BiFunction<? super T, ? super T, ? extends T> op) Accumulates the elements of this Foldable by successively calling the given operation `op` from the right. Parameters op:BiFunction<? super T, ? super T, ? extends T> An operation of type T Returns:Option<T> Some of reduced value or None. Exceptions NullPointerException: if `op` is null

public Option<T> reduceRightOption(BiFunction<? super T, ? super T, ? extends T> op)

Accumulates the elements of this Foldable by successively calling the given operation op from the right.

Parameters

op:BiFunction<? super T, ? super T, ? extends T>: An operation of type T

Returns:Option<T>

Some of reduced value or None.

Exceptions

NullPointerException:: if op is null

public Interface Foldable<T>

Method Summary

Method Detail