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![You need `_.cloneDeep()` at javascript
var a = [1, 2, 3]
a.flatMap(z => [z, z+3]) => return value is [1, 4, 2, 5, 3, 6]
var b = [{x: 1}, {x: 2}, {x: 3}]
var c = b.flatMap(z => [z, z[“x”]]) => c is [{x: 1}, 1, {x: 2}, 2, {x: 3}, 3]
c[0][“x”] = 6; => b is [{x: 6}, {x: 2}, {x: 3}]](https://image.slidesharecdn.com/theproductivitybroughtbyclojure-190610162318/85/The-productivity-brought-by-Clojure-27-320.jpg)
Uploaded byLaurence Chen
The productivity brought by Clojure
The document discusses the productivity benefits of Clojure, including REPL-driven development, immutable data structures, functional programming, and the immutable Datomic database. REPL-driven development allows writing and testing code incrementally. Immutable data structures and functional programming eliminate the need for deep cloning and enable better function composability. The immutable Datomic database allows "time travel" queries on historical data without additional tables. In summary, Clojure offers improvements to test-driven development, data handling, and database queries through these features.
The productivity brought by Clojure
- 1. The productivity brought byClojure Laurence Chen http://twitter.com/humorless
- 3. Motivation behind thistalk ● 2019 Stackoverflow survey: Clojure programmers get highest salary ● But, in Taiwan You will find no job if you tell your boss that you want to use Clojure.
- 4. Most important reasonsto love Clojure from survey ● Lisp & REPL-driven development ● Immutable data structures/Functional programming ● JVM & Java interoperation
- 5. Part One ● Clojureis a dialect of Lisp ● REPL-driven development
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- 7. Lisp is afamily of programming languages 1. CommonLisp 2. Scheme 3. Racket 4. Clojure 5. Hylang 6. Emacs Lisp - elisp 7. WASM - WebAssembly
- 8. S-expression v.s. M-expression S-expression ●(fn x y) ● (+ a b) M-expression ● fn(a, b) ● sort(colloection)
- 9. ● Beating theaverage (超越平庸)
- 10. Test-driven development ● Edittest file ● Edit code file ● Run the program
- 11. Areas of improvement 1.Can we get immediate feedback? 2. Can we write and test incrementally? 3. Can we test even smallest unit? For example, single expression or statement?
- 12. Editor which canjudge the boundry of s-expression. REPL-driven development Write test argument in Editor Write source code in Editor Clojure REPL Send source/test to REPL Get result back
- 13. Demo ● Example EditorCommand: cqp ● Evaluate at the prompt
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- 17. Demo ● Example EditorCommand: cpp ● Evaluate the current expression
- 20. Demo ● Example EditorCommand: > )
- 23. Editor integration andsemantic editing ● cqp => Evalute at the prompt ● cpp => Evaluate the current expression ● :Require => reload the whole file ● [ d => jump to definition ● > ) => slurp ● < ) => barf ● cseb => surround the current element with parentheses ● dsf => delete surrounding parentheses
- 24.
- 25. Q & A ●How much productivity improvement will you have from REPL-driven development? at least 30% ● Can REPL-driven programming be used in other programming languages? Yes, but ... ● Can macro (meta-programming) be used in other programming languages? Yes, but ...
- 26. Part Two ● Immutabledata structures ● Composable functions
- 27. You need `_.cloneDeep()`at javascript var a = [1, 2, 3] a.flatMap(z => [z, z+3]) => return value is [1, 4, 2, 5, 3, 6] var b = [{x: 1}, {x: 2}, {x: 3}] var c = b.flatMap(z => [z, z[“x”]]) => c is [{x: 1}, 1, {x: 2}, 2, {x: 3}, 3] c[0][“x”] = 6; => b is [{x: 6}, {x: 2}, {x: 3}]
- 28. Functional programming dilemma ●Passing data by value ○ Guarantee that any changes will only affect local scope. ○ Extremely inefficient ● Passing data by reference ○ Save memory/Fast ○ Code is more difficult to reason about ○ Not safe at multi-thread environment
- 29. Clojure immutable datastructure: copy on write
- 30. There is no`cloneDeep` in Clojure ● Garbage collection => obsoletes `delete` (Manually track memory allocation/deallocation) ● Immutable data structure => obsoletes `cloneDeep` (Manually manage data references)
- 31. Function composability inJavaScript is not good Object/Map Array Functions defined on Object/Map Functions defined on Array ??
- 32.
- 33. Collection <-> Sequence<-> Transformation library Set Map Vector List Sequence map, filter, reduce, first, rest, mapcat, apply, take, drop, ... Lazy sequences, strings, Lines in a flie, Files in a directory, ….
- 35.
- 36. Q & A ●How much productivity improvement will you have from immutable data structures and composable functions? at least 30% ● Can immutable data structures and composable functions be used in browser? Yes, ClojureScript
- 37. Part Three ● Immutabledatabase - Datomic
- 38. database queries Orders Excel filesdailyETL I want to know the revene data today.
- 39. temporal database queries Orders/Orders history Excel filesdaily ETL I want to know the revene data today. I want to know the revenue data last week.
- 40. Immutable database allowstime traveling ● orders history table is the analogy of `_.cloneDeep` ● In Datomic, you only need orders table and `(as-of db t)` ● SQL:2011 also support temporal databases ● PostgreSQL has temporal_tables extensions
- 41. Conclusion ● You canhave better Test-driven development. ● You can forget _.cloneDeep(). ● You can have better function composability. ● You can have immutable database.
- 42. ● Thank you ●Q & A
- 43. Bibliography 1. stackoverflow survey2019 2. xkcd.com/297 Lisp Cycles 3. Dmitri Sotnikov --- Clojure distilled 4. Rich Hickey --- “Clojure Concurrency” talk 5. Juan-Manuel Gimeno --- Functional programming in clojure