What are some examples of type constraints in programming?

What are some examples of type constraints in programming?

Type constraints are rules that restrict the types of values that can be used in a function or a data structure. For example, in TypeScript, you can use the extends keyword to constrain a generic type to a specific type or interface.

Can you give me a specific example in TypeScript?

Sure! Here's a simple example:

function logLength<T extends { length: number }>(item: T): void {
    console.log(item.length);
}

In this function, T is constrained to types that have a length property.

What about in Python? Are there similar constraints?

In Python, you can use type hints with the typing module. For example, you can use List to specify that a function expects a list of a certain type:

from typing import List

def process_items(items: List[int]) -> None:
    for item in items:
        print(item)

Are there any downsides to using type constraints?

Yes, while type constraints can improve code safety and readability, they can also make the code more complex and harder to maintain, especially for beginners.