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Scala Programming · Module 8 of 10

Functional programming ideas

Pure functions and immutability make Scala code predictable.

📖 Key ideas

  1. A pure function returns the same output for the same input and has no side effects.
  2. Immutability means data is never changed in place.
  3. Composition builds big functions from small ones (f andThen g).
  4. Referential transparency: an expression can be replaced by its value.
  5. Libraries like Cats Effect and ZIO manage side effects safely.
💡 Real-life example: Like a calculator: 2 + 3 always shows 5 and never secretly changes your bank balance.
Pure functionSame input, same output, no side effects
Side effectChanging something outside the function
CompositionCombining functions into one
ZIOLibrary for managing effects