We'll visit some of the mistakes or issues that we can encounter while working with scala, and how we can solve them. We'll also go through some of the common and preferred practices in Scala.

1. Presented By: Miral Gandhi
Revisit
Best practices in Scala

2. Lack of etiquette and manners is a huge turn off.
KnolX Etiquettes
Punctuality
Respect Knolx session timings, you
are requested not to join sessions
after a 5 minutes threshold post
the session start time.
Feedback
Make sure to submit a constructive
feedback for all sessions as it is
very helpful for the presenter.
Silent Mode
Keep your mobile devices in silent
mode, feel free to move out of
session in case you need to attend
an urgent call.
Avoid Disturbance
Avoid unwanted chit chat during
the session.

3. Our Agenda
0103:30 PM Problems & Solutions
0203:50 PM Common Practices
0303:55 PM Demo examples

4. Case classes
Case classes should be final

5. Enumeration
Problem: Runtime Error, as case is not handled

6. Enumeration
Problem: Type Erasure

7. Enumeration: Solutions
Use Sealed case objects

8. Sealed Traits

9. Sealed Traits
Problem: Seal might get leak
Solution: final case class

10. Arrays
Problem: Reference Equality is checked

11. Arrays
Solution: Here we can use sameElements method to compare values of an
Array
In Scala 2.13 we have ArraySeq which solves this problem for immutable
Array

12. Implicit Conversions
Problem: We are performing operation on incompatible types

13. Implicit Conversions
Use explicit conversions:
Use Implicit Conversions to enhance existing types

14. Implicit Resolution
Problem: Ambiguous Reference

15. Implicit Resolution
No full proof solution: Try to give proper explicit names, make it as
elaborate as possible

16. String concatenation using +

17. String Concatenation
● Use String interpolation
● Call toString explicitly
Note: String concatenation has been deprecated in Scala 2.13

18. Exceptions
● MUST NOT throw exceptions for validations of user input or flow control
Instead Use:
○ Option
○ Either
○ Try
● MUST NOT catch Throwable when catching Exceptions

19. Errors
Problem: How to model user defined errors

20. Say No to Return
return statement signal side effects as it alters the flow of the method.
It leads to multiple exit points which is anti-structural programming
For eg:

21. MUST NOT use magic values
Problem: Intent of solution is not clear, could lead to unnecessary issues.
Solution: Use : Option, Either, Try or create your own ADT’s.

22. Type Annotation
Scala currently infers the most specialized type possible

23. Type Annotation
Change in Implementation:
Problem: This could lead to incompatibility
Solution: Provide explicit type annotation for public methods

24. Common Practices
● Do not use null
● Never use Option.get
● Give meaningful names
● Should break long functions
● Set Maximum Line length: prefered 120

25. References
● https://portal.klewel.com/watch/webcast/scala-days-2019/talk/49/
● https://github.com/alexandru/scala-best-practices/

26. Thank You !
Get in touch with us:
miral.gandhi@knoldus.com