The document discusses the concept of making illegal states unrepresentable in data structures for real-world applications, focusing on synchronization issues in various storage locations such as local and cloud services. It emphasizes the importance of managing execution and storage effectively to avoid errors and ensure efficient synchronization. The repeated phrase 'make illegal state unrepresentable' highlights the key principle throughout the discussion.

1. Data types for the
Real World ™
Eric Torreborre
YOW LambdaJam 2015

2. Yaron Minsky Make illegal state
unrepresentable!
Make illegal state
unrepresentable!

3. Make illegal state
unrepresentable!
Make illegal state
unrepresentable!
Real W
orld?
Constraints
CS
Data
structures

4. “File line”

8. Errors
interpret

9. Errors

10. Data
structures

11. Non-empty list

13. CS

14. Parser

16. Real World?

18. S3 EC2 EMR

19. sync
sync
sync
storage
execution execution

20. sync
storage
execution
“Local”

21. storage
execution
“Local - test”

22. sync
storage
“Hadoop”
execution

23. sync
storage
execution
“Hadoop - test”

24. sync
storage
“Hadoop – half sync”
execution

25. main

26. Location

29. Run application

30. “sync” files
download?
where?
how?
upload?

31. “sync” files
sync dir valid?

32. sync
sync
sync
storage
execution execution

33. Execution location

35. “sync” directory
unrepresentable!

37. “sync” locations
download?
where?

38. location execution
local local
hdfs
S3 local
hdfs
hdfs local
hdfs

39. Synchronized location

40. createSynchronizedLocation
9 cases
unrepresentable!

41. synchronize
efficient!

42. Locations
Location
ExecutionLocation
SynchronizedLocation
Datatypes are
cheap!

43. Make illegal state
unrepresentable!
Make illegal state
unrepresentable!
For the Real World ™