What is the difference between type inference and type checking?

What is the difference between type inference and type checking?

Type inference is the ability of a programming language to deduce the type of a variable automatically, while type checking is the process of verifying that a variable's type is correct during compilation or runtime.

Can you give me an example of type inference?

Sure! In languages like JavaScript, if you write let x = 5;, the interpreter infers that x is a number.

And what about type checking?

Type checking ensures that operations on variables are valid. For instance, trying to add a string to a number would raise an error in statically typed languages.

Are there languages that use both type inference and type checking?

Yes, languages like TypeScript and Scala use both. They infer types but also enforce type checks to catch errors early.