What are the differences in semantics in programming?

Semantics in programming defines the meaning and significance of language constructs. Differences manifest in how the language interprets and executes code.

Main types of semantics:

• Static semantics: Checks the correctness of a program before execution, such as data types and lexical scope. Static semantic errors are detected at compile time.
• Dynamic semantics: Determines how a program behaves during execution, including the sequence of operations, memory management, and error handling.
  • Operational semantics: Describes program execution through a sequence of steps of an abstract machine or transitions from one state to another.
  • Denotational semantics: Links programming constructs to mathematical objects (e.g., functions), providing an abstract, execution-independent definition of meaning.
  • Axiomatic semantics: Defines properties of a program through a system of logical axioms and inference rules, often used to prove program correctness (e.g., using preconditions and postconditions).

Examples of differences in iOS development:

• ARC (Automatic Reference Counting): Dynamic memory management semantics in Swift/Objective-C. Determines when objects are released based on references.
• Protocols and extensions in Swift: Affect static semantics, allowing adding functionality to existing types or defining behavior contracts.
• Error handling (do-catch in Swift): Dynamic semantics that determine how a program reacts to errors during execution.