Getting to 100% Kotlin: A practical guide

A lot of teams are super excited by Kotlin and are ready to go all-in with it. But while exciting, it can also be stressful — learning a brand new language while converting old code and writing new features, all at the same time? How does a team get there as smoothly as possible?

We’re here to help! At Basecamp we’ve worked hard to make our codebase 100% Kotlin over the course of the last year. We learned a lot and want to share a roadmap of how you can get there too.

If you're just starting out with Kotlin but can already see its potential, this talk is for you. We’ll share our best overarching strategies and tips based on a year of real-world shipping — how to get started, how to keep moving forward, and pitfalls to keep an eye out for.

No theory here, this is all based on our actual experiences getting to 100% Kotlin.

(Talk given at Android Summit 2017 on 8/24/17 and Droidcon NYC 2017 on 9/25/17)

Transcript

1. Getting to 100% Kotlin: A practical guide dan@basecamp.com @dankim
2. Why was Kotlin important to us?
3. It made me happy!
4. Running headfirst into the unknown
5. Learn the language (and ship)
6. Convert our backlog of Java (and ship)
7. What pitfalls should we watch out for?
8. ✅ Practical, low-stress strategies
9. Get real with production code
10. Start with small conversions
11. No tests!
12. Getting excited is important!
13. Start with small conversions
14. Start with small conversions ✅ POJOs / Models
15. Start with small conversions ✅ POJOs / Models ✅ Util methods
16. Start with small conversions ✅ Adapters ✅ POJOs / Models ✅ Util methods
17. Start with small conversions ✅ Adapters ✅ POJOs / Models ✅ Util methods Entire Retrofit implementation
18. Forget about being perfect
19. ✌Idiomatic Kotlin✌
20. Don’t get too caught up in it
21. Find yourself in some serious rabbit holes
22. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
23. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
24. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
25. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
26. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
27. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
28. fun processAccounts(accounts: List<Account>?) {
 for (account in accounts!!) {
 if (account.active) {
 ...
 } else if (account.trial) {
 ...
 } else {
 ...
 }
 }
 }
29. Find a few key concepts that click *for you*
30. Find a few key concepts that click *for you*
31. Find a few key concepts that click *for you* ✅ Flow control
32. Find a few key concepts that click *for you* ✅ Flow control ✅ Collections
33. Find a few key concepts that click *for you* ✅ Flow control ✅ Collections ✅ Extension functions
34. The auto converter is your friend
35. Side by side learning
36. You’re only ~60% done (don’t ship it)
37. Take it to the finish line
38. ❄ Use cool downs for Kotlin
39. Leave the campsite cleaner than you found it
40. Things might get ugly
41. Curb your enthusiasm
43. fun success(inboxItems: InboxItems) = with(inboxItems.withoutPings()) { doAsync { CachePrefs.setInboxCache(context, this@with) } }
44. fun success(inboxItems: InboxItems) = with(inboxItems.withoutPings()) { doAsync { CachePrefs.setInboxCache(context, this@with) } }
45. fun success(inboxItems: InboxItems) = with(inboxItems.withoutPings()) { doAsync { CachePrefs.setInboxCache(context, this@with) } }
46. fun success(inboxItems: InboxItems) = with(inboxItems.withoutPings()) { doAsync { CachePrefs.setInboxCache(context, this@with) } }
47. fun success(inboxItems: InboxItems) = with(inboxItems.withoutPings()) { doAsync { CachePrefs.setInboxCache(context, this@with) } }
48. fun success(inboxItems: InboxItems) {
 val items = inboxItems.filterNot { ... } 
 doAsync { CachePrefs.setInboxCache(context, items) }
 }
49. fun success(inboxItems: InboxItems) {
 val items = inboxItems.filterNot { ... } 
 doAsync { CachePrefs.setInboxCache(context, items) }
 }
50. fun success(inboxItems: InboxItems) {
 val items = inboxItems.filterNot { ... } 
 doAsync { CachePrefs.setInboxCache(context, items) }
 }
51. fun success(inboxItems: InboxItems) {
 val items = inboxItems.filterNot { ... } 
 doAsync { CachePrefs.setInboxCache(context, items) }
 }
52. fun success(inboxItems: InboxItems) {
 val items = inboxItems.filterNot { ... } 
 doAsync { CachePrefs.setInboxCache(context, items) }
 }
53. Keep an eye on your code organization
54. Don’t forget about your customers
55. Programmer happiness is crucial!
56. Your customers don’t care
57. Take your time
58. 430 days!
59. It’s just a number
60. Thank you! dan@basecamp.com @dankim