Understanding Type Systems
Static vs Dynamic Typing

What is a Type System?

A type system is a set of rules that assigns a property called "type" to the various components of a program, such as variables, expressions, functions, or modules. Types help the system ensure that operations are performed on compatible kinds of data.

Static Typing

In a statically typed language, the type of a variable is known at compile-time. This means the programmer must declare what type each variable is, and type checking is performed before the code runs.

int age = 25
string name = "Alice"
bool isStudent = true

Output:

Variable 'age' is of type int
Variable 'name' is of type string
Variable 'isStudent' is of type bool

Dynamic Typing

In a dynamically typed language, the type of a variable is known at runtime. Variables can be assigned without declaring their type explicitly, and their types can change as the program runs.

var value = 42       // value is now a number
value = "hello"      // value is now a string
value = true         // value is now a boolean

Output:

value: number
value: string
value: boolean

Key Differences

Static Typing	Dynamic Typing
Type is checked at compile-time	Type is checked at runtime
Errors caught early	Errors caught during execution
More verbose (requires type declarations)	Less verbose (no explicit types needed)
Examples: int age = 25	Example: var age = 25

Why does this matter?

Understanding type systems helps you write safer and more maintainable code. Knowing whether you're working with static or dynamic typing changes how you approach debugging, error handling, and code organization.

Let’s build some intuition

Question: Why might a compiler reject this code in a statically typed system?

int age = "twenty-five"

Answer: Because you are assigning a string to a variable declared as an integer. The compiler detects this mismatch and throws an error before the program even runs.

Question: What happens if you run the same code in a dynamically typed system?

var age = "twenty-five"

Answer: The program will not throw an error immediately because dynamic typing allows this. However, if later operations assume age is a number (e.g., age + 1), a runtime error may occur.

Pros and Cons

• Static Typing Pros: Catches errors early, better for large codebases, IDEs offer better autocomplete.
• Static Typing Cons: Requires more boilerplate and type annotations.
• Dynamic Typing Pros: Faster to write, flexible during prototyping.
• Dynamic Typing Cons: Risk of runtime errors, harder to debug in large projects.

Conclusion

Whether a language uses static or dynamic typing affects how you declare variables, handle errors, and structure programs. As a programmer, understanding these systems helps you choose the right approach based on your project’s needs.