no.finn.lambdacompanion

Class Functions

java.lang.Object

no.finn.lambdacompanion.Functions

public final class Functions
extends Object

Method Summary

Modifier and Type	Method and Description
static <A,B> B	foldLeft(BiFunction<A,B,B> accumulator, B b, List<A> list)
static <A,B> B	foldRight(BiFunction<A,B,B> accumulator, B b, List<A> list)
static <A> A	head(List<A> list)
static <A> List<A>	tail(List<A> list)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

foldRight

public static <A,B> B foldRight(BiFunction<A,B,B> accumulator,
                                B b,
                                List<A> list)

Type Parameters:

A - a

B - b

Parameters:

accumulator - accumulator

b - b

list - list

Returns:

b Head recursive fold. Fold the list by combining the first element with the results of combining the rest

Example:

 
    :                                    f
   / \       foldRight f z ->           / \
  1   :                                1   f
     / \                                  / \
    2  []                                2   z
 
 

foldLeft

public static <A,B> B foldLeft(BiFunction<A,B,B> accumulator,
                               B b,
                               List<A> list)

Type Parameters:

A - a

B - b

Parameters:

accumulator - accumulator

b - b

list - list

Returns:

b Tail recursive fold. Fold the list by recursively combining the results of combining all but the last element with the last one

Example:

 
    :                                    f
   / \       foldLeft f z ->            / \
  1   :                                f   2
     / \                              / \
    2  []                            z   1
 
 

head

public static <A> A head(List<A> list)

Type Parameters:

A - a

Parameters:

list - list

Returns:

first element of the given list.

Throws:

IndexOutOfBoundsException - if the list is empty

tail

public static <A> List<A> tail(List<A> list)

Type Parameters:

A - a

Parameters:

list - list

Returns:

all but the first elements of the given list

Throws:

IndexOutOfBoundsException - if the list is empty