Type inference in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is type inference in Go?

Type inference in Go means the compiler can figure out the type of a variable automatically based on the value assigned to it, so you don't always have to write the type explicitly.

beginner

How do you declare a variable with type inference in Go?

You use the := operator to declare and initialize a variable without specifying its type. For example: name := "Alice" lets Go infer that name is a string.

beginner

What happens if you assign a number to a variable using := in Go?

Go infers the variable's type as int if you assign an integer value, or float64 if you assign a decimal number. For example, age := 30 makes age an int.

intermediate

Can you change the type of a variable after using type inference in Go?

No, once Go infers a variable's type, it cannot be changed. The variable keeps the inferred type for its entire lifetime.

beginner

Why is type inference useful in Go?

Type inference makes code shorter and easier to read by removing the need to write types explicitly when they are obvious from the value. It helps beginners focus on logic rather than types.

What does the := operator do in Go?

A Declares a constant

B Assigns a value to an existing variable without type inference

C Declares and initializes a variable with type inference

D Imports a package

The := operator declares a new variable and lets Go infer its type from the assigned value.

If you write x := 3.14 in Go, what type does Go infer for x?

A int

B string

C bool

D float64

Go infers the type float64 for decimal numbers like 3.14.

Can you write var age := 30 in Go?

A No, := cannot be used with var

B No, because 30 is not a valid value

C Yes, but it declares a constant

D Yes, it declares age with type inference

The := operator is used without var. Using var and := together is a syntax error.

What type will Go infer for flag := true?

A bool

B string

C int

D float64

Go infers the bool type for true or false values.

Why might you choose to use explicit types instead of type inference in Go?

A To make the code longer

B To clarify the variable's type for readability or specific needs

C Because type inference is not supported

D To avoid using variables

Explicit types can improve clarity or handle special cases where the inferred type is not what you want.

Explain how type inference works in Go and give an example of declaring a variable using it.

Think about how Go figures out the type without you writing it.

Describe one advantage and one limitation of using type inference in Go.

Consider what makes code simpler and what restrictions inference brings.