Keynote talk given at JDay Lviv 2014 in Ukraine (http://www.jday.com.ua/). Video coming soon. Abstract: Some say that there's nothing new under the sun. However, looking back on five to six decades of computing, it's easy to see that things progress at their own leisurly pace. Structured programming, originating in the '60s, did not gain mainstream adoption until the '80s; object-oriented programming was hotly debated in the '70s and '80s but only gained widespread acceptance in the '90s. Every couple of decades sees an engineering leap that radically improves the software engineering discipline across the board. I believe we are now at such an inflection point, with functional programming concepts slowly sifting into the mainstream. After this talk, I hope you will too.

1. Functional Leap of
Faith
Tomer Gabel, Wix
JDay Lviv 2014

2. Through the Looking Glass
20 years ago…
• C/C++ rule the
market [1]
• First release of Java
[1] TIOBE Index (historical data)

3. … since then?*
• C and Java are neck-and-neck
• Virtual machines are everywhere
• Garbage collection is everywhere
• OOP is everywhere
* Not exhaustive

4. Virtual Machines
1967 BCPL
1978 UCSD p-System
1994 JVM
2014 Everywhere!

5. Garbage Collection
1960 Formalized[1]
1970s Research
1994 JVM
2014 Everywhere!
[1] Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I

6. Object-Oriented Programming
1967 Simula 67
1980 Smalltalk 80
1983 C++
2014 Everywhere!

7. Advances take
decades to become
mainstream

8. Market Growth[1]
3000
2500
2000
1500
1000
500
0
1975 1980 1985 1990 1995 2000 2005 2010 2015* 2020*
Units (Millions)
[1] eTForecasts Worldwide PC Market Research Report

9. 3000
2500
2000
1500
1000
500
0
1975 1980 1985 1990 1995 2000 2005 2010 2015* 2020*
Units (Millions)
Market Growth
• Structured Programming
• Module Systems
• Dynamic Memory Allocation

10. 3000
2500
2000
1500
1000
500
0
1975 1980 1985 1990 1995 2000 2005 2010 2015* 2020*
Units (Millions)
Market Growth
• Garbage Collection
• OOP
• VMs and JIT

11. 3000
2500
2000
1500
1000
500
0
1975 1980 1985 1990 1995 2000 2005 2010 2015* 2020*
Units (Millions)
Market Growth
You are here!

12. What’s holding us
back?

13. The Market has Shifted
• SaaS is the norm
• Shorter time to
market
• Latency requirements
are stricter
• Availability is
business-critical

14. The Free Lunch is Over[1]
[1] The Free Lunch is Over, Herb Stutter (Dr. Dobb's Journal, 2005)
• CPUs aren’t getting
(much) faster
• Rather, they’re getting
parallel
• Concurrency is the
new kid on the block

15. Datasets are Getting Bigger
• Terabyte-scale data is
common
• Computation demand
– NoSQL
– Big Data
• Specialized hardware
(SAN) is a hindrance

16. We need new
abstractions.

17. Three desirable
attributes:

18. Today’s systems
are highly available & reliable.
Tomorrow’s abstraction must…
encourage correct code.

19. Complexity is the Mind Killer
• Complex system  bigger codebase
• More code  more bugs
• We want less code
• We want correct code

20. Control flow  Data flow
We need to invert our thinking.

21. How  What
We need to invert our thinking.

22. Control flow describes the
how
List<Person> adults(List<Person> in) {
ArrayList<Person> out = new ArrayList<>();
for (Person p : in)
if (p.getAge() >= 18)
out.add(p);
return out;
}

23. Data flow describes the what
List<Person> adults(List<Person> in) {
return in.stream()
.filter(p -> p.age >= 18)
.collect(Collectors.toList());
}

24. “What” is Better
• Focuses on the
problem
• Reduces accidental
complexity
• Decouples intent from
execution

25. Today’s systems
are highly concurrent.
Tomorrow’s abstraction must…
encourage immutability.

26. The Case for Immutability
• Inherently thread-safe
• Referentially
transparent
• Easier to reason
about!

27. Today’s systems
are horizontally scalable.
Tomorrow’s abstraction must…
simplify workload distribution.

28. Distribution 101
1. Take a core
computation
2. Split it out
3. Run on many nodes
4. Profit

29. Why is this hard?
• Behavior-as-data
• Side effects
• High-performance
frameworks
 Lambdas
 Immutability
 Akka, Hadoop,
Storm…

30. The future is
functional.
1. Data flow-oriented
2. Immutable
3. Easy to distribute

31. tomer@tomergabel.com
@tomerg
http://il.linkedin.com/in/tomergabel
THANK YOU FOR YOUR TIME!