Iterable

Dependency

maven central

WARNING

This package is an experiment with iterables that I find useful. There are probably better things like streams and common libraries that do things better than this code.

You may experience performance problems and errors of various kinds.

Description

This library provides some functions and utilities that implement of a number of commonly used functional programming functions.

The provided code is meant to be used to produce new collections using side-effect free code.

The code provides static methods defined in the Iterables class and fluent java style methods.

Methods / Functions

Start by using an Iterables static function. To start you either wrap your iterable (List, Set, etc...) using the appropriate method:

Collection	Method
Iterable	Iterables.it
List	Iterables.it
Array	Iterables.ar
var arg	Iterables.ar
nothing	Iterables.empty
object	Iterables.singleton

or you use a method that implements some function:

Function
Iterables.map
Iterables.filter
Iterables.foldR
Iterables.foldL
Iterables.filter

You can use methods on the returned iterable using fluent style.

You then collect things with some method:

Collection	Method
Set	asSet
List	asList
List	asMList
Map	asMap

which produce the result using the java util collections.

Examples

Suppose we have a class

class Person {
   public final String name;
   ...
}

and a list of persons l.

List<Person> l;

Create an index

We can create a name indexed map using directly

Iterables.asMap(l, p -> p.name, p -> p);

or using fluent style

Iterables.it(l)
         .asMap(p -> p.name, p -> p);

or using a specialized method

Iterables.asValueMap(l, p -> p.name);

Filter

We create the set of names that start with "A"

Iterables.map(l, p -> p.name)
         .filter(n -> n.startsWith("A"))
         .asSet();