What are the differences between “untyped” & “dynamically typed” programming languages?

When learning different programming languages, you may come across terms like untyped and dynamically typed. While they may sound similar, they represent different concepts in how programming languages manage data types. In this article, we will explore these concepts with clear examples and comparisons.

What is an Untyped Language?

Untyped programming languages do not have strict data type definitions. Variables can hold any type of value without explicit type declarations, and the language treats all data as a uniform type internally.

Example of Untyped Behavior

JavaScript demonstrates untyped characteristics where variables can hold any value:

// x can hold any type of value
let x = 5;          // number
console.log(x);

x = "hello";        // string  
console.log(x);

x = true;           // boolean
console.log(x);

x = [1, 2, 3];      // array
console.log(x);

5
hello
true
[ 1, 2, 3 ]

Advantages and Disadvantages of Untyped Languages

What is a Dynamically Typed Language?

In dynamically typed languages, type checking occurs at runtime during program execution. Variables have types, but these types are determined and checked when the program runs, not when it's compiled. Languages like Python, JavaScript, Ruby, and PHP are dynamically typed.

Example of Dynamic Typing

JavaScript shows dynamic typing where variables have types that can be checked at runtime:

// Variables have types that can be checked at runtime
let x = 5;         
console.log(typeof x);  // Check type

x = "hello";    
console.log(typeof x);  // Type changed

x = 3.14;       
console.log(typeof x);  // Still a number in JavaScript

number
string
number

Key Characteristics of Dynamic Typing

Dynamic typing allows flexibility but requires runtime type checking, which can impact performance. The interpreter must verify types during execution, potentially leading to runtime errors if incompatible operations are attempted.

Untyped vs Dynamically Typed Languages

Choosing Between Approaches

The choice depends on your project requirements:

• For rapid prototyping: Dynamically typed languages offer quick development
• For large applications: Consider statically typed languages for better error detection
• For system programming: Lower-level languages may be more appropriate

Conclusion

While untyped languages treat all data uniformly, dynamically typed languages maintain type information that's checked at runtime. Understanding these concepts helps you choose the right language for your programming needs and write more effective code.