Clojure on Android

Tools, techniques and practices to write Android apps in Clojure.

Transcript

1. CLOJURE ON ANDROID ALEX YAKUSHEV @UNLOG1C
2. INTRO Have been participating in GSoC for 4 years on Clojure's behalf. Worked on Clojure-Android during years 1 and 2 Wrote Project Skummet last year Now working on enabling TDD and CI support for Clojure- Android projects Author of Compliment library Graduated a week ago, now have to figure what I'm doing with my life
3. PLAN 1. General information 2. Clojure-Android tools 3. Clojure-Android applications 4. How to get started
4. WHAT IS CLOJURE-ANDROID? Umbrella term for multiple projects: our own Clojure forks a build tool idiomatic wrapper library different dev tooling, etc. Started in 2011 by Daniel Solano Gómez.
5. WHY CLOJURE INSTEAD OF JAVA? Because we can! All advantages of Clojure the language. REPL-driven development. Logic, data and UI are all in one language.
6. WHAT ABOUT CLOJURESCRIPT + REACT NATIVE/PHONEGAP/…? Arguments for Clojure-Android: Closer to native platform Easier to learn for Android developers [Arguably] Better tooling support [Unconfirmed] Simpler interop [Unconfirmed] Suits better for a multithreaded environment
7. WHAT ABOUT CLOJURESCRIPT + REACT NATIVE/PHONEGAP/…? Arguments for ClojureScript + X: Faster startup time Easier to dive in for web developers Potential to write (kinda-)cross-platform applications [Unconfirmed] Access to JavaScript libraries @swannodette
8. GOALS OF CLOJURE-ANDROID 1. Let Android developers write good apps in Clojure. 2. Let Clojure developers write good Android apps.
9. PLAN 1. General information 2. Clojure-Android tools 3. Clojure-Android applications 4. How to get started
10. LEIN-DROID https://github.com/clojure-android/lein-droid/ Plugin for Leiningen. Handles compilation, packaging, minification, and deployment on the device.
11. LEIN-DROID CRASH COURSE Show help: l e i n d r o i d h e l p Create a new project: l e i n d r o i d n e w A w e s o m e A p p c o m . m e g a c o r p . a w e s o m e a p p Do everything else: l e i n d r o i d d o a l l
12. COMING SOON: BOOT-DROID
13. NEKO https://github.com/clojure-android/neko Neko is a Clojure-Android toolkit library. Wraps different Android API facilities. Takes care of dynamic compilation, REPL, CIDER.
14. NEKO.UI This is how Android XML UI looks like: < ? x m l v e r s i o n = " 1 . 0 " e n c o d i n g = " u t f - 8 " ? > < L i n e a r L a y o u t x m l n s : a n d r o i d = " h t t p : / / s c h e m a s . a n d r o i d . c o m / a p k / r e s / a n d r o i d " a n d r o i d : o r i e n t a t i o n = " v e r t i c a l " > < E d i t T e x t a n d r o i d : i d = " @ + i d / n a m e " a n d r o i d : h i n t = " Y o u r n a m e " a n d r o i d : l a y o u t _ w i d t h = " f i l l _ p a r e n t " a n d r o i d : l a y o u t _ h e i g h t = " w r a p _ c o n t e n t " > < / E d i t T e x t > < B u t t o n a n d r o i d : i d = " @ + i d / s e n d " a n d r o i d : t e x t = " S e n d " > < / B u t t o n > < / L i n e a r L a y o u t >
15. NEKO.UI And this is neko.ui declaration: [ : l i n e a r - l a y o u t { : o r i e n t a t i o n : v e r t i c a l } [ : e d i t - t e x t { : i d : : n a m e : l a y o u t - w i d t h : f i l l : h i n t " Y o u r n a m e " } ] [ : b u t t o n { : i d : : s e n d : t e x t " S e n d " : o n - c l i c k ( f n [ _ ] ( s e n d - i n p u t . . . ) ) } ] ]
16. NEKO.UI Able to do this: ( c o n c a t [ : l i n e a r - l a y o u t { : o r i e n t a t i o n : h o r i z o n t a l } ] ( f o r [ i ( r a n g e 1 0 ) ] [ : b u t t o n { : t e x t ( s t r i ) : l a y o u t - w i d t h [ 3 5 : d p ] : o n - c l i c k ( f n [ _ ] ( t o a s t ( s t r " C l i c k e d " i ) ) ) } ] ) )
17. NEKO.UI Or even some really crazy stuff: ( l e t [ l a n d s c a p e ? ( = ( n e k o . u i / g e t - s c r e e n - o r i e n t a t i o n ) : l a n d s c a p e ) ] [ : r e l a t i v e - l a y o u t { } [ : e d i t - t e x t { : i d : : u s e r n a m e : h i n t " Y o u r n a m e " } ] [ : b u t t o n { : i d : : s e n d : t e x t " S e n d " ( i f l a n d s c a p e ? : l a y o u t - t o - r i g h t - o f : l a y o u t - b e l o w ) : : u s e r n a m e } ] ] )
18. NEKO.UI Accessing created UI elements: ( r e q u i r e ' [ n e k o . f i n d - v i e w : r e f e r [ f i n d - v i e w ] ] ) ( f i n d - v i e w a c t i v i t y : : n a m e ) = > # o b j e c t [ a n d r o i d . w i d g e t . E d i t T e x t . . . ] ( c o n f i g ( f i n d - v i e w a c t i v i t y : : s e n d ) : e n a b l e d f a l s e )
19. NEKO.DATA.SQLITE By default, working with SQLite on Android means: Writing SQL to create tables Writing SQL to query the database Awkwardly extracting data from Cursor C u r s o r c u r s o r = d b . q u e r y ( " e m p l o y e e s " , n e w S t r i n g [ ] { " n a m e " , " s a l a r y " , " a c t i v e " } , " _ i d = % " , 1 ) ; c u r s o r . m o v e T o N e x t ( ) ; S t r i n g n a m e = c u r s o r . g e t S t r i n g ( 0 ) ; l o n g s a l a r y = c u r s o r . g e t L o n g ( 1 ) ; b o o l e a n a c t i v e = c u r s o r . g e t B o o l e a n ( 2 ) ;
20. NEKO.DATA.SQLITE In Neko you can define a schema: ( r e q u i r e ' [ n e k o . d a t a . s q l i t e : a s d b ] ) ( d e f d b - s c h e m a ( d b / m a k e - s c h e m a : n a m e " l o c a l . d b " : v e r s i o n 1 : t a b l e s { : e m p l o y e e s { : c o l u m n s { : _ i d " i n t e g e r p r i m a r y k e y " : n a m e " t e x t n o t n u l l " : v a c a t i o n " b o o l e a n " : b o s s _ i d " i n t e g e r " } } : b o s s e s { : c o l u m n s { : _ i d " i n t e g e r p r i m a r y k e y " : n a m e " t e x t n o t n u l l " } } } ) ) ( d e f g e t - d b - h e l p e r ( m e m o i z e ( f n [ ] ( d b / c r e a t e - h e l p e r d b - s c h e m a ) ) ) ) ( d e f n g e t - d b [ ] ( d b / g e t - d a t a b a s e ( g e t - d b - h e l p e r ) : w r i t e ) )
21. NEKO.DATA.SQLITE Inserting rows: ( d b / i n s e r t ( g e t - d b ) : e m p l o y e e s { : n a m e " S h e l l e y L e v e n e " : v a c a t i o n f a l s e } ) Updating rows: ; ; S e n d e m p l o y e e s w i t h I D s 1 , 5 a n d 7 o n v a c a t i o n ( d b / u p d a t e ( g e t - d b ) : e m p l o y e e s { : v a c a t i o n t r u e } { : _ i d [ : o r 1 5 7 ] } ) Querying database: ; ; F i n d a l l e m p l o y e e s n o t o n v a c a t i o n ( d b / q u e r y - s e q ( g e t - d b ) : e m p l o y e e s { : v a c a t i o n f a l s e } ) = > ( { : _ i d 5 , : n a m e " D a v e M o s s " , : v a c a t i o n f a l s e } { : _ i d 8 , : n a m e " R i c k y R o m a " , : v a c a t i o n f a l s e } )
22. NEKO.DATA.SQLITE Also supports: querying multiple tables querying scalar values batch inserts
23. NEKO.DATA.SHARED-PREFS Provides an atom wrapper for SharedPreferences: ( d e f p r e f e r e n c e s m y - p r e f s " p r e f _ f i l e " ) ( s w a p ! m y - p r e f s a s s o c : l a s t - u s e r " j o e " ) ; ; A p p l i c a t i o n i s r e s t a r t e d a t s o m e p o i n t . ( : l a s t - u s e r @ m y - p r e f s ) = > " j o e "
24. NEKO.DIALOG.ALERT ( - > ( a l e r t - d i a l o g - b u i l d e r a c t i v i t y { : m e s s a g e " D i a l o g m e s s a g e " : c a n c e l a b l e t r u e : p o s i t i v e - t e x t " O K " : p o s i t i v e - c a l l b a c k ( f n [ _ _ _ ] ( t o a s t " C l i c k e d O K " ) ) : n e g a t i v e - t e x t " C a n c e l " : n e g a t i v e - c a l l b a c k ( f n [ d i a l o g _ ] ( . c a n c e l d i a l o g ) ) } ) . c r e a t e . s h o w ) )
25. NEKO Besides mentioned, simplifies work with: activities action bars menus intents resources data adapters notifications
26. PROJECT SKUMMET https://github.com/alexander-yakushev/clojure/tree/skummet Optimizing Clojure compiler From Norwegian skummet — skimmed, fat-free
27. HOW CLOJURE COMPILES VARS From c l o j u r e / c o r e _ _ i n i t . c l a s s : c o n s t _ _ 1 5 8 1 = ( V a r ) R T . v a r ( " c l o j u r e . c o r e " , " p r - s t r " ) ; c o n s t _ _ 1 5 8 4 = ( A F n ) R T . m a p ( n e w O b j e c t [ ] { . . . } ) ; . . . c o n s t _ _ 1 5 8 1 . s e t M e t a ( ( I P e r s i s t e n t M a p ) c o n s t _ _ 1 5 8 4 ) ; c o n s t _ _ 1 5 8 1 . b i n d R o o t ( n e w c o r e . p r _ s t r ( ) ) ; From code that uses c l o j u r e . c o r e / p r - s t r : V a r p r _ s t r = ( V a r ) R T . v a r ( " c l o j u r e . c o r e " , " p r - s t r " ) ; . . . ( ( I F n ) p r _ s t r . g e t R a w R o o t ( ) ) . i n v o k e ( . . . ) ; Huge part of Clojure loading time comes from initializing vars http://blog.ndk.io/2014/02/25/clojure- bootstrapping.html
28. HOW SKUMMET COMPILES VARS From c l o j u r e / c o r e $ p r _ s t r . c l a s s : p u b l i c s t a t i c I F n _ _ i n s t a n c e = n e w c o r e . p r _ s t r ( ) ; From code that uses c l o j u r e . c o r e / p r - s t r : c o r e $ p r _ s t r . _ _ i n s t a n c e . i n v o k e ( . . . ) ;
29. BENEFITS OF LEAN COMPILATION Less time spent initializing vars Compiled _ _ i n i t classes are smaller Dereferencing vars is faster Smaller memory footprint Functions aren't anymore tied to namespaces which allows to use Proguard
30. OTHER SKUMMET FEATURES Doesn't emit macros Doesn't emit r e f e r statements Can mark specific vars as non-lean if they are used as Var objects. Can compile basically anything that doesn't call e v a l in the code, e.g.: Clojure, core.async
31. SKUMMET BENCHMARKS On Android: Clojure Skummet Reduction Load time, seconds 4.02 1.00 75.1% APK size, KB 1669 696 58.3% Heap usage, KB 5469 2750 49.7% More rigorous and extensive benchmarks: http://blog.ndk.io/2015/04/23/state-of-coa.html
32. PLAN 1. General information 2. Clojure-Android tools 3. Clojure-Android applications 4. How to get started
33. 4CLOJURE APP https://play.google.com/store/apps/details?id=org.bytopia.foreclojure Solve 4Clojure problems online or offline, synchronizes with your 4clojure.com account.
34. CLARITY KEYBOARD BETA https://play.google.com/store/apps/details?id=com.swiftkey.clarity.keyboard Created by Adam Clements and his team at Swiftkey. Utilizes NLP to auto-correct whole phrases. Built with lein-droid, core.async, Skummet. Read more http://swiftkey.com/en/blog/what-makes-clarity-keyboard-tick-clojure/
35. NIGHTWEB (DISCONTINUED) https://sekao.net/nightweb/ Created by Zach Oakes. Peer-to-peer social network that runs over I2P.
36. PLAN 1. General information 2. Clojure-Android tools 3. Clojure-Android applications 4. How to get started
37. WHERE TO WRITE CLOJURE- ANDROID PROJECTS? CIDER Any other nREPL client: fireplace.vim, Counterclockwise, Cursive. Nightcode
38. DOCUMENTATION AND HELP Lein-droid and Neko wikis and Marginalia docs #clojure-android IRC at Freenode clojure-android at Google Groups http://clojure-android.info/
39. FUTURE PLANS More Skummet improvements (make it even faster) Boot-droid Bring the new hip things to Neko, e.g. Material design Propose a reliable asynchronous mechanism for Clojure- Android projects Become obscenely rich and make my own mobile platform that runs Clojure
40. WE NEED PEOPLE! To bring up new usecases. To write apps. To contribute code and docs. To discover and report bugs. To prove that Clojure is a first-class language for Android.
41. LIVE DEMO
42. ACKNOWLEDGMENTS Daniel Solano Gómez and Zach Oakes for GSoC mentorship and their work. Adam Clements, Artur Malabarba, and the rest Clojure- Android contributors. Chas Emerick for nREPL. Bozhidar Batsov and Tim King for nrepl.el/CIDER. Rich Hickey and all Clojure community for creating Clojure and keeping it awesome.
43. THANK YOU!