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Swift Academy · Lesson

Generic Constraints and where Clauses

Applying multiple constraints, same-type requirements and conditional extensions.

Generic Basics Recap

Generics let you write flexible, reusable code that works with any type.

func identity<T>(_ value: T) -> T { return value }
print(identity(42))
print(identity("hello"))

Single Type Constraint

Constrain a generic parameter to conform to a protocol using T: Protocol.

func largest<T: Comparable>(_ a: T, _ b: T) -> T {
  return a > b ? a : b
}
print(largest(3, 7))

All lessons in this course

  1. Generic Constraints and where Clauses
  2. Opaque Types with some Keyword
  3. Existentials with any and Type Erasure
  4. Primary Associated Types and Typed Throws
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