Type Safety

A type specifies a collection of values that have similar traits. Type safety makes sure that, when you have a variable of a specific type, you cannot assign a different value of a different type to the variable. Type safety in a language is important, because it means that you have predictable and defined behaviour.

// Variable declaration
int := 100
int = 200 // This will work!

A variable called "int" is declared with the value: 100, the value: 100 is of type "Integer". The row below the variable "Int" gets assigned the value of 200.

// Variable declaration
int := 100
int = "Hello" // This will NOT work! Different types

Again a variable is declared with the value: 100, which we just learned is an "Integer". The row below "int" gets assigned "Hello" which is of type "String". This is does not align with the idea of type-safety and thus results in an error.

Specifying Types

Instead of inferring types like above, it is also possible to specify types directly. This will ensure that everyone can easily see what the type is. In addition it will also check the initial assignment, making sure its of the right type.

// Works fine!
int x := 100

// Errors with a type check failure
int x := "Hello World!"