From Python to Kotlin - TalkingKT 2019

Talk presenting a real life feedback from a rewriting of some scripts in Python into Kotlin - talking about languages features, running scripts, tooling, etc. This was presented at TalkingKT 2019 on 5th March 2019.

I'm sure you already know that Kotlin is cool, you wouldn't be there otherwise. But can we stop a second to ask ourselves: what does it concretely brings to the table? Let's avoid the usual comparison with Java - and instead, talk about what Kotlin offers for some almost-scripting tooling, coming from Python. This talk is a real field feedback about the re-coding of a Python tool into Kotlin from the ground up.

Transcript

1. 1 From Python to Kotlin @Horgix / #TalkingKT 5 March 2020 From Python to Kotlin Feedback from some scripts re-writing Alexis “Horgix” Chotard
2. 2 From Python to Kotlin @Horgix / #TalkingKT Alexis “Horgix” Chotard SRE & Coach DevOps ▼ 30% Development ▼ 40% Operations ▼ 30% Training, coaching, … ▼ Usually prototypes in Python ▼ First time Kotlin user in Oct. 2019 ▼ Loves Rust @Horgix Horgix
3. 3 From Python to Kotlin @Horgix / #TalkingKT Warning! This is a personal feedback from a personal experience Lot of bias from my own knowledge :)
4. 4 From Python to Kotlin @Horgix / #TalkingKT Context & Usage Talks/Speakers handling from GitHub files
5. 5 From Python to Kotlin @Horgix / #TalkingKT Sample - Talks list
6. 6 From Python to Kotlin @Horgix / #TalkingKT Sample - Talk file template
7. 7 From Python to Kotlin @Horgix / #TalkingKT What do we want to do? ▼ Files “parsing” - YAML frontmatter + Markdown body ▼ “Error” detection : missing infos, non-coherent infos, etc. ▼ Some stats would be nice ▼ Will be run mainly manually or from a CI pipeline
8. 8 From Python to Kotlin @Horgix / #TalkingKT First Python implementation “Hey, let’s code something quick to make our life easier”
9. 9 From Python to Kotlin @Horgix / #TalkingKT At first, a simple set of Python scripts
10. 10 From Python to Kotlin @Horgix / #TalkingKT Then some “tests”
11. 11 From Python to Kotlin @Horgix / #TalkingKT “Let’s wrap everything in a Makefile!”
12. 12 From Python to Kotlin @Horgix / #TalkingKT “Well, that look hacky as f***…” And indeed. It is was
13. 13 From Python to Kotlin @Horgix / #TalkingKT Rewrite everything in Kotlin! (for science)
14. 14 From Python to Kotlin @Horgix / #TalkingKT Why Kotlin? ▼ Lot of momentum ▼ Looked cool and I wanted to play with it :) ▼ A lot of data collections computing that can all be done in memory ▽ Functional approach made easy by Kotlin ▽ Kotlin standard library looked like it could make things easier
15. 15 From Python to Kotlin @Horgix / #TalkingKT Let’s compare some use cases Mainly about language features, libraries and stuff
16. 16 From Python to Kotlin @Horgix / #TalkingKT 1. Talks format handling and base language constructs
17. 17 From Python to Kotlin @Horgix / #TalkingKT Talk formats - Storage & field format
18. 18 From Python to Kotlin @Horgix / #TalkingKT Talk formats - Storage & field format
19. 19 From Python to Kotlin @Horgix / #TalkingKT Talk formats - Storage & field format (raw)
20. 20 From Python to Kotlin @Horgix / #TalkingKT Some wise words
21. 21 From Python to Kotlin @Horgix / #TalkingKT Better than enums : Enum classes <3
22. 22 From Python to Kotlin @Horgix / #TalkingKT Yes, there are (more limited) enums in Python too...
23. 23 From Python to Kotlin @Horgix / #TalkingKT 1bis. Talks format handling What about getting our enum value from what we parse?
24. 24 From Python to Kotlin @Horgix / #TalkingKT How to get a Enum value from our initial String Python:
25. 25 From Python to Kotlin @Horgix / #TalkingKT Pattern matching <3 Python: Kotlin:
26. 26 From Python to Kotlin @Horgix / #TalkingKT Function extensions <3 Python: Kotlin:
27. 27 From Python to Kotlin @Horgix / #TalkingKT 2. File parsing YAML frontmatter + Markdown body
28. 28 From Python to Kotlin @Horgix / #TalkingKT File parsing in Python :) https://github.com/eyeseast/python-frontmatter
29. 29 From Python to Kotlin @Horgix / #TalkingKT File parsing in Python :) https://github.com/eyeseast/python-frontmatter
30. 30 From Python to Kotlin @Horgix / #TalkingKT File parsing in Kotlin :( https://github.com/atlassian/commonmark-java/ + commonmark-ext-yaml-front-matterc
31. 31 From Python to Kotlin @Horgix / #TalkingKT File parsing in Kotlin :( https://github.com/atlassian/commonmark-java/ + commonmark-ext-yaml-front-matterc
32. 32 From Python to Kotlin @Horgix / #TalkingKT 3. Directories browsing YAML frontmatter + Markdown body
33. 33 From Python to Kotlin @Horgix / #TalkingKT Directories browsing in Python :(
34. 34 From Python to Kotlin @Horgix / #TalkingKT Directories browsing in Kotlin :)
35. 35 From Python to Kotlin @Horgix / #TalkingKT Bootstrapping & Running Getting started on a minimal software/script and running it manually or in a CI pipeline
36. 36 From Python to Kotlin @Horgix / #TalkingKT Bootstrap - From installed tooling to a working “project” ▼ Python : ▽ Virtualenv ▽ pip install + pip freeze > requirements.txt ▽ Profit ▼ Kotlin : ▽ Maven Gradle configuration ▽ Directory/files structure way more strict/predefined ▽ IntelliJ IDEA “New Project” to the rescue
37. 37 From Python to Kotlin @Horgix / #TalkingKT Running in a CI Pipeline ▼ Python: cache dependencies & just run ▼ Kotlin: need to rebuild just in case ▼ Docker to the rescue
38. 38 From Python to Kotlin @Horgix / #TalkingKT Kotlin script .kts
39. 39 From Python to Kotlin @Horgix / #TalkingKT Kotlin script ▼ .kts files ▼ Top level instructions ▼ kotlinc -script <file>.kts ▼ Can be used for your Gradle files :) ▼ Does not support multiple files :( https://kotlinlang.org/docs/tutorials/command-line.html#using-the-command-line-to-run-scripts
40. 40 From Python to Kotlin @Horgix / #TalkingKT kscript https://github.com/holgerbrandl/kscript
41. 41 From Python to Kotlin @Horgix / #TalkingKT kscript - Imports, libraries and entrypoint definition
42. 42 From Python to Kotlin @Horgix / #TalkingKT kscript surprise n°1 - Imports clash
43. 43 From Python to Kotlin @Horgix / #TalkingKT kscript surprise n°2 - Bad handling of typealias
44. 44 From Python to Kotlin @Horgix / #TalkingKT kscript works fine in the end :) Demo
45. 45 From Python to Kotlin @Horgix / #TalkingKT Take away What did I take away from this switch from Python to Kotlin
46. 46 From Python to Kotlin @Horgix / #TalkingKT Take away ▼ Easier / More lightweight to start with Python than Kotlin ▼ More complex to run Kotlin scripts than Python, but kscript saves the day ▼ Thanks Kotlin interoperability with Java ▼ Community libraries are tailored to the language usual use cases ▼ List comprehension vs functional chaining ▼ ❤ Enum Classes ▼ ❤ Pattern matching ▼ ❤ Extension functions
47. 47 From Python to Kotlin @Horgix / #TalkingKT Take away - Self-Q&A ▼ Did I get to re-implement all the things in Kotlin? ▽ Nope, didn’t implement README generation because parsing files was already too much of a pain, so generating them… ▼ What are the key differences between both implementations in the end? ▽ Kotlin version looks way more clean and maintainable to me ▼ If I were to do it again, would I do it in Python or Kotlin? ▽ Same, first Python then Kotlin :)
48. 48 From Python to Kotlin @Horgix / #TalkingKT 5 March 2020 From Python to Kotlin Feedback from some scripts re-writing Alexis “Horgix” Chotard Q&A