Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Java 8: Lambdas, Monads and Java Collections
Search
Grzegorz Piwowarek
July 06, 2015
Programming
1
91
Java 8: Lambdas, Monads and Java Collections
Presented during Confitura 2015
Grzegorz Piwowarek
July 06, 2015
Tweet
Share
More Decks by Grzegorz Piwowarek
See All by Grzegorz Piwowarek
Javaslang DevoxxBE 2016
pivovarit
1
120
Javaslang DevoxxMA
pivovarit
2
750
JavaSlang JavaDayKiev 2016
pivovarit
0
65
Javaslang - functional Java done right
pivovarit
0
200
Java Wars VIII: The Function Awakens
pivovarit
0
640
Java 8 vs. Checked Exceptions
pivovarit
0
100
Other Decks in Programming
See All in Programming
PHP で読む楽しいコアダンプ
sji
0
240
GitHub Copilot Tips and Tricks
yuichielectric
26
7.4k
Migrating to Signals: A Practical Workshop
manfredsteyer
PRO
0
280
BuefyのMaintainerを引き継いだ件
kikuomax
0
510
Go1.22からの疑似乱数生成器について/go-122-pseudo-random-generator
convto
1
160
Laravel標準バリデーションでできること
hmb_ok
2
360
Why 1 + 1 = 2 in Swift?
1plus4
1
240
Docker ハンズオン / docker-hands-on
suzukihoge
51
16k
ここ1~2年くらいで 使えるようになった(主要ブラウザーの最新版 がすべて対応した ) ウェブの新機能について ランダムに喋る!
myzkyy
9
6.4k
PHPerKaigi 2024〜10年以上動いているレガシーなバッチシステムを Kubernetes(Amazon EKS) に移行する取り組み〜
tshinowpub
1
220
Creating Retro-Style Photos Using Swift
ski
1
340
DDDはなぜ難しいのか / 良いコードの定義と設計能力の壁
pospome
24
6.7k
Featured
See All Featured
Automating Front-end Workflow
addyosmani
1353
200k
The Invisible Side of Design
smashingmag
293
49k
Ruby is Unlike a Banana
tanoku
95
10k
Docker and Python
trallard
33
2.6k
The Success of Rails: Ensuring Growth for the Next 100 Years
eileencodes
28
5.9k
Music & Morning Musume
bryan
39
5.5k
10 Git Anti Patterns You Should be Aware of
lemiorhan
644
57k
What's in a price? How to price your products and services
michaelherold
236
11k
ParisWeb 2013: Learning to Love: Crash Course in Emotional UX Design
dotmariusz
101
6.6k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_iinuma
67
38k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
8
8.2k
Web Components: a chance to create the future
zenorocha
304
41k
Transcript
JAVA 8 LAMBDAS, MONADS && JAVA COLLECTIONS Grzegorz Piwowarek
GRZEGORZ PIWOWAREK @PIVOVARIT
GRZEGORZ PIWOWAREK @PIVOVARIT visionsoftondal.com
Plan: -lambda expressions -java.util.function -monad -Optional -Stream
lambda expressions (...) -> statement - Anonymous function
lambda expressions x -> x + 1
lambda expressions x -> x + 1 - No type
information
lambda expressions x -> x + 1 () -> 42
() -> {return 42;} (x, y) -> {} () -> {}
method references
java.util.function
java.util.function
Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T>
Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T>
Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T>
Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T>
Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T>
Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T>
Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T>
Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T>
Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T>
Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T>
MONAD
None
GOOGLE IMAGES...
...
MONAD Design pattern http://got-steam.com/
Why bother? : Boilerplate -1 Readability +1 Complexity -1 Responsibility
-1
type: M<T> "unit": T -> M<T> "bind": M<T>.bind(T -> M<U>)
= M<U> MONAD "bind": M<T>.bind(T -> U)= M<U>
type: M<T> "unit": T -> M<T> "bind": M<T> bind(T ->
M<U>) = M<U> MONAD "bind": M<T>.bind(T -> U)= M<U>
"bind": M<T> bind(T -> U)= M<U> What if U: M<?>
?
"bind": M<T> bind(T -> U)= M<U> What if U: M<?>
?
"bind": M<T> bind(T -> U)= M<U> What if U: M<?>
? http://www.ivanaborovnjak.com/project/box-in-a-box/
Monads in Java 8 Optional Stream CompletableFuture
Monads in Java 8 Optional Stream CompletableFuture
Optional Encapsulation of operations on optional values
Optional type: M<T> "unit": T -> M<T> "bind": M<T> bind(T
-> M<U>) = M<U>
Optional type: Optional<T> "unit": T -> M<T> "bind": M<T> bind(T
-> M<U>) = M<U>
Optional type: Optional<T> "unit": Optional.ofNullable(), Optional.of() "bind": M<T> bind(T ->
M<U>) = M<U>
Optional type: Optional<T> "unit": Optional.ofNullable(), Optional.of() "bind": Optional.flatMap()
Filtering an Optional .filter(Predicate<T>)
Unwrapping an Optional .get() .orElse(T default) .orElseGet(Supplier<T>) .orElseThrow(Supplier<Ex>) .ifPresent(Consumer<T>)
Java 7 style
Java 8 style
Java 8 style - flatMap
Java 7,5 style ;)
Java 7,5 style ;)
Stream Encapsulation of operations on multiple items
Stream type: Stream<T> "unit": Stream.of(), Arrays.stream(), Collection.stream() "bind": Stream.flatMap()
Stream
Stream
Stream
Stream && Optional
Stream lazy-initialized nonreusable
intermediate operations .map() .flatMap() .filter() .peek()
intermediate operations .map() .flatMap() .filter() .peek() Stream not consumed: does
not print anything
Java7
Java8
Consuming Stream .forEach(Consumer<T>) .collect() .reduce(BinaryOperator<T>) .allMatch(), anyMatch(), noneMatch() .findFirst(), findAny()
.count() .toArray()
Stream.reduce()
Collectors .toList(), toMap(), toSet(), toCollection() .minBy(), maxBy() .joining() .partitioningBy() ...and
many others
Collectors.toList()
Collectors.toMap()
Collectors.joining()
Debuggability? IntelliJ IDEA: - v14.0 - partial support - v15.0
- full support
Stream in APIs BufferedReader.lines() Files.newDirectoryStream() Random.ints() ...
you want more?
https://github.com/ jasongoodwin/better-java-monads
Thank You!
REFERENCES: -"MONADIC JAVA" BY MARIO FUSCO -"WHAT'S WRONG WITH JAVA
8" BY PIERRE-YVES SAUMONT -WWW.ORACLE.COM -"A FISTFUL OF MONADS" - LEARN YOU A HASKELL FOR GREAT GOOD