Scala: Context & Observability

Slides for The Art of Scala presentation in Warsaw on 25th May 2023

Transcript

1. Scala:
   Context & Observability
   

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2. Context propagation
   explicit
   parameter
   implicit
   parameter
   

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3. Thread-safe state on
   JVM
   AtomicRef ThreadLocal
   Every thread has its own local copy
   of the state which is not visible to
   the others
   Shared state safely updated by many
   threads using optimistic concurrency (CAS)
   

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4. Context propagation
   on JVM
   ThreadLocal
   InheritableThreadLocal
   DynamicVariable
   

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10. Scope
    Lexical Dynamic
    Depends on location in source
    code
    Depends on method call
    graph
    

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14. Functional context
    propagation
    ReaderT / Kleisli
    (cats)
    IOLocal
    (cats-effect)
    Context functions
    (scala 3)
    

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15. Context propagation
    with cats-mtl
    Ask Local Stateful
    read-only environment
    effect
    dynamic scope
    effect
    shared mutable state
    effect
    

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23. Local + log4cats
    demo
    

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25. Local + log4cats + IOLocal
    demo
    

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28. Scala 3
    Context Functions
    

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30. linktr.ee/mbednarz
    

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