Utilizing IsType for Basic Type Assertions in Go

With the advent of generics in Go 1.18, developers have gained a powerful new tool for type assertions: IsType. This function allows for a more concise and safe way to determine if a value is of a specific type.


Go's type system is robust and versatile, but before generics, asserting the type of a basic type stored in an interface was somewhat verbose and could lead to runtime panics if not handled correctly. The introduction of generics has brought the IsType function, which simplifies this process. This article will focus on using IsType with basic types such as integers, floats, and strings.

The IsType Function

IsType is a generic function that can be used to check if an interface{} value is of a specific type. It returns a boolean indicating the result of the type assertion.

Defining IsType

Here's a basic implementation of the IsType function:

func IsType[T any](value any) bool {
    _, ok := value.(T)
    return ok

Using IsType with Basic Types


var intValue interface{} = 42
if IsType[int](intValue) {
    fmt.Println("The value is an int")


var floatValue interface{} = 3.14
if IsType[float64](floatValue) {
    fmt.Println("The value is a float64")


var stringValue interface{} = "hello"
if IsType[string](stringValue) {
    fmt.Println("The value is a string")

Benefits of Using IsType

  1. Simplicity: IsType reduces the traditional multi-line type assertion to a single line of code.
  2. Safety: It avoids the risk of a runtime panic by returning a boolean result instead of causing a panic when the assertion fails.
  3. Readability: The use of IsType makes the code more readable and the intention clearer to other developers.
  4. Generics: It leverages the power of generics, allowing for a type-safe and reusable function that works with any type.

Performance Considerations

While IsType introduces a slight overhead due to the use of generics, benchmarks have shown that the performance impact is negligible for most applications. The safety and convenience it provides often outweigh the minimal performance cost.


The IsType function is a significant addition to Go's type system, especially for dealing with basic types stored in interfaces. It offers a modern, safe, and expressive way to perform type assertions. As Go continues to evolve, the use of generics and functions like IsType will likely become more prevalent, enhancing the language's ability to handle type assertions with ease and confidence.