If you think SBT is complex, then you should read this. SBT is really simple as long as you get to know it.

1. SBT Made Simple
@囚千任 - http://afoo.me
Monday, September 9, 13

2. Immutability
Monday, September 9, 13

3. Setting
• A Build File is just a sequence of Settings
• A Setting is just a transformation to key-
value pairs
• A Transformation to some key-value pair is
immutable
Monday, September 9, 13

4. State Transition
• Project State is volatile
• state transition is immutable
Monday, September 9, 13

5. Composition
Monday, September 9, 13

6. Task
• dependency model to composition model
• task composition to form bigger granularity
unit
Monday, September 9, 13

7. InputTask
• Task with input
• input validation and completion support
with parser
• parser combinator is a form of composition
Monday, September 9, 13

8. Command
• Special InputTask
• accept Project state and settings as input
• project state is driven by a composition of
command execution
Monday, September 9, 13

9. Modularity
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10. Monday, September 9, 13

11. Configuration
• Ivy concept similar to Maven’s Scope
• Predefined or custom Configurations setup
Modularity boundary
Monday, September 9, 13

12. Project
• project is another level of modularity
• multiple project build definitions have their
specific configuration
Monday, September 9, 13

13. Plugins
• SBT plugin mechanism is another
modularity strategy
• enhance reusability too.
Monday, September 9, 13

14. Consistency
One Rule To Rule Them All
Monday, September 9, 13

15. Same Effect?
name := {
“hello” + “sbt”
}
sbt := {
“hello” + “sbt”
}
Monday, September 9, 13

16. Not Really!
name := {
“hello” + “sbt”
}
sbt := {
“hello” + “sbt”
}
=> Setting[String]
=> Setting[Task[String]]
Monday, September 9, 13

17. Key is the key
val name = settingKey[String](“desc.”)
name := {
“hello” + “sbt”
}
val sbt = taskKey[String](“task desc”)
sbt := {
“hello” + “sbt”
}
=> Setting[String]
=> Setting[Task[String]]
Monday, September 9, 13

18. Key is the key
• SettingKey[T]
• TaskKey[T]
• InputKey[T]
Monday, September 9, 13

19. Demo Time~
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20. Monday, September 9, 13