Javaone - Getting Funky with Groovy
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This document discusses functional programming concepts in Groovy including closures, iterators, streams, partial evaluation, composition, memoization, and tail calls. It provides examples of using closures to solve problems like finding the cheapest/most expensive beer and total price. Advantages of Groovy like Java interoperability and libraries like GPars for parallel programming are mentioned. Resources for learning more about functional programming in Groovy are listed at the end.
Javaone - Getting Funky with Groovy
- 1. GETTING FUNKY WITH ANDRES ALMIRAY IX-CHEL RUIZ @AALMIRAY @IXCHELRUIZ
- 5. FUNCTIONAL GROOVY, ARE YOU KIDDING ME?
- 6. GROOVY IS NOT HASKELL RUSSEL WINDER * have a look at https://github.com/frege/frege
- 7. CLOSURES == FUNCTIONS Closures are functions (i.e, blocks of code) with an environment containing a binding for all free variables of the function
- 8. CLOSURES == FUNCTIONS Closures are NOT side effect free by design
- 9. CLOSURES: PARAMETERS (1) Parameter types may be omitted if type information is not needed
- 10. CLOSURES: PARAMETERS (2) Parameters may have default values NOTE: Default values must be defined from right to left
- 11. CLOSURES: DEFAULT PARAMETER Closures may have a default parameter named it
- 12. CLOSURES LEAD TO … Iterators Streams Partial Evaluation Composition Memoization Tail calls
- 13. ITERATORS (1)
- 14. ITERATORS (2) p
- 15. ITERATORS
- 16. GEEKS & BEERS Mattias Johan Functional Java Lambdaj Google Guava
- 17. USE CASES Given a list of beers and their prices: • Find the cheapest beer • Find the most expensive beer • What’s the name of the most expensive beer • Get all the beer names • What’s the total price
- 18. USE CASE 1 Find the cheapest beer
- 19. USE CASE 2 Find the most expensive beer
- 20. USE CASE 3 What’s the name of the most expensive beer
- 21. USE CASE 4 Get all the beer names
- 22. USE CASE 5 What’s the total price
- 23. PROS & CONS Java collections Closures! Plays nice with all other functional frameworks Metaprogramming! Non-lazy evaluation Streams not included in core filter/map/reduce
- 24. S/COLLECT/MAP/ Don’t like collect? Use Groovy’s metaprogramming
- 25. STREAMS (1) Lazy generators. Extension module created by @tim_yates http://timyates.github.com/groovy-stream/
- 26. STREAMS (2) Groovy is Java friendly. Use any Java library such as functional-java
- 27. FJ MODULE EXTENSION https://github.com/mperry/functionalgroovy Update: Mark has posted some notes at http://mperry.github.io/2013/07/28/groovy-null-handling.html
- 28. STREAMS (JDK8) Collection and Lambda friendly, lazy evaluation
- 29. PARTIAL EVALUATION (1) Currying creates a new closure with fixed parameters, left to right
- 30. PARTIAL EVALUATION (2) Currying may be applied right to left too, even on an arbitrary index
- 31. OBJECTS AS PARTIAL EVALS Any class may implement the call() method, enabling implicit evaluation
- 32. COMPOSITION (1) Closures may be composed (left to right) using the >> operator
- 33. COMPOSITION (2) Closures may be composed (right to left) using the << operator
- 34. MEMOIZATION Cache computed values for increased performance
- 35. TAIL CALLS (1) Recursive closures may use Tail Calls thanks to trampoline()
- 36. TAIL CALLS (2) Apply @TailRecursive on methods https://github.com/jlink/tailrec/ now included in Groovy 2.3!
- 37. METHODS AS CLOSURES Any method may be transformed to a Closure using the .& operator
- 38. IMMUTABILITY The @Immutable AST transformation makes writing immutable classes trivial
- 39. GPARS http://gpars.codehaus.org/ Concurrent collection processing Composable asynchronous functions Fork/Join abstraction Actor programming model Dataflow concurrency constructs CSP Agent - an thread-safe reference to mutable state
- 40. PARALLEL COLLECTIONS Gpars enhances JDK/GDK collections with parallel execution enabled versions
- 42. RESOURCES • http://pragprog.com/magazines/2013-01/using-memoization- in-groovy • http://www.ibm.com/developerworks/views/java/ libraryview.jsp?search_by=functional+thinking • https://github.com/jlink/tailrec/ • http://timyates.github.com/groovy-stream • http://www.jroller.com/vaclav • http://gpars.codehaus.org • http://www.slideshare.net/arturoherrero/functional-programming- with-groovy
- 43. THANK YOU! HTTP://PEOPLE.CANOO.COM/SHARE Andres Almiray Ix-chel Ruiz @aalmiray @ixchelruiz