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Type system 類型系統

Top type​

Parent of all type

  • Object (Javascript, Java, C#)

  • any, unknown (TypeScript)

  • std::any (C++)

  • object (Python)

  • Any? (Kotlin)

  • interface{} (Go)

Unit type​

Only one instance

  • Unit (Kotlin, Scala)

  • NoneType (Python)

  • Void (Java, Swift)

  • Null, Undefined (JavaScript)

Bottom type​

Zero instance, no possible value allowed

  • never (Typescript)

  • Void (Haskell)

  • type.Never (Python)