Java-adamant

A library enhancing the JRE with the core functionality it should have had for a long time.

The core ideas are:

• Collections are value objects and therefore immutable (persistent data stractures, changes create new collections, the originating one kept unchanged)
• java.util.List and the util-Collection-API just stay alive because of its wide spread not its quality
• Collections are fully type-safe! (no contains(Object) and such)
• Collections are thread-safe by concept (no additional API or impl., wrappers or runtime-exceptions)
• Eager evaludation is (in most cases) the appropriate way to solve problems in Java (even tho' we work immutable)
• null is avoided as far as possible - it is not considered as a valid value (e.g. as a collection's element)
• Interfaces should be narrow/minimal (1 method for most of em) - a rich set of utile functions comes from combining and composing minimal interfaces (maximized decoupling)
• functions should be combinable with a minimal use of generics (specialised interfaces + adapters over single general + multiple generics)
• favour pure functions (stateless functions, therefore often constants - code describes what to do when a value becomes available)
• Reflection is pain - concepts have to be compile-time save
• There is no natural order - order depends on the point of view (Comparable is not a satisfactory solution)
• Iterator / Iterable is badly designed and needs a replacement (there is a 'legacy' support to integrate in common frameworks anyway)

About

'jadamant' is a made-up word conbined out of 'Java' and 'Adamant'. Inspired by the Master of Orion II Adamantium plating. Adamant symbolises the immutable solid character and thereby the philosophy of this project.

Status

The 0.1 beta is planed to be released somewhen 2012. Until then there might be major changes to the API. But the core collection API is nearly stable pretty much done implemented and covered with tests.

Feal free to contact me and get to know more about the current state.

Notable facts about jadamant's persistent collections

• All collections are immutable (read-only; changes create new objects, the originating one kept unchanged)
• All collections are not Iterable ~ this concept got replaced too
• The API is index based or orientated (see the examples to get the difference)
• Lists are the basic collection (there is no Collection-type)
• Often Lists consists of a chain of partial Lists
• A Bag is literally a Sorted``List
• A Set is literally a special Bag (and therefore a List too) with a unique constraint
• A Map is literally a Set of Entrys, so it's a Bag too... and a List... and...
• a Multimap (a Bag of Entrys) or a map with a list of values for each key

This migth sound unfamiliar for a moment. Hopefully there will be a lot of examples soon to show why this is the better approch.

Working with Lists

// list construction
List.with.noElements(); // a empty list
List.with.element(1); // a list with a single element - the integer 1
List.with.elements(1,2,3,4); // a list holding the numbers 1 to 4

to be continued...

You should have a look to the unit-tests in the de.jbee.lang and de.jbee.lang.seq package to see the current API in use.