lambda : Java Glossary

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lambda expression
A lambda is just a terser way to implement an instance of a one-use anonymous class that has a single method. You don’t have to specify the name of the interface the class implements, the name of the class or the name of the callback method. You do not have to specify the types of the parameters, just their names and the method body. You can leave off the () around the parameter, if there is only one parameter. You can leave off the ; and the {} around the body if the body is only one statement (the usual case). The compiler infers all it needs. In return for all this abbreviation, you must add -> between the parameters and the method body.

Church’s abstraction of function calls. Delegate objects in Java were always considerably more clumsy than C/C++’s callbacks or closures in Smalltalk, even though they were more generic, allowing multiple callbacks and variables to be passed as a single delegate bundle. Java’s delegates also had the advantage of structure, implementing an interface. With Java 1.8, Oracle decided to streamline delegates and allow you to pass little hunks of code as parameters. These are formally called lambda λ expressions or closures. You would think this could be adequately explained in a paragraph or two, however there are now entire books on them. I have not yet experimented with them, so, for now, I will have to refer you to these books.

Lambdas are not quite the same an anonymous classes. They don’t have a reference to the enclosing class, for example. This allows for speed optimisations, especially when there are multiple threads.

Java implemented just a small part of lambda calculus. It left out monads, lazy evaluation, extended immutability.

Why all the fuss over a terser delegate syntax? They make it easier to encapsulate code for processing entire collections in parallel.

Books

book cover recommend book⇒Java 8 Lambdas: Pragmatic Functional Programmingto book home
by Richard Warburton 978-1-4493-7077-0 paperback
publisher O’Reilly recommended 978-1-4493-7085-5 eBook
published 2014-04-07 B00J3B3J3C kindle
Explanation of lambda expressions aka closures added in Java 1.8. There expressions have been integrated into all parts of Java. This book will help you explore these ramification such as streams, parallelism, concurrency, Collections. The book presumes your are already familiar with other parts of the Java language. This book might be described as lambda immersion. The author rarely shows traditional code then the lambda code equivalent. His examples never show output, so you have no way of verifying if you understood what the code did. For the most part, he talks in abstract academic language, which I found hard to understand. I will have to read this book several times before I understand it. On other hand, I wrote a little bit of code to iterate over a Map with a lambda expression and it worked first time and I fully understood how it worked. You can download the exercises from GitHub I bought an eBook copy of this book on 2014-07-18.
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book cover recommend book⇒Functional Programming in Java: Harnessing the Power Of Java 8 Lambda Expressionsto book home
by Venkat Subramaniam 978-1-937785-46-8 paperback
birth 1966 age:50 B00J8W0OTI kindle
publisher Pragmatic Bookshelf
published 2014-03-01
This is not just about a new wrinkle to Java syntax, but a whole new functional programming style.
Australian flag abe books anz abe books.co.uk UK flag
German flag abe books.de amazon.co.uk UK flag
German flag amazon.de abe books.ca Canadian flag
Spanish flag amazon.es amazon.ca Canadian flag
Spanish flag iberlibro.com Chapters Indigo Canadian flag
French flag abe books.fr abe books.com American flag
French flag amazon.fr amazon.com American flag
Italian flag abe books.it Barnes & Noble American flag
Italian flag amazon.it Nook at Barnes & Noble American flag
India flag junglee.com Kobo American flag
UN flag other stores Google play American flag
O’Reilly Safari American flag
Powells American flag
Greyed out stores probably do not have the item in stock. Try looking for it with a bookfinder.

Videos

Implementing Lambda Expressions in Java click to watch
Lambda Speed Considerations click to watch The Oracle employee delivering this lecture has a thick Russian accent. It takes some getting used to.

Learning More

Oracle’s Javadoc on Stream Interface : available:

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