What is Type Safety?


7 minutes read


Kristopher Sandoval

Feb 21, 2024

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Whenever we talk about technology, it’s easy to get lost in the myriad of terms, phrases, and buzzwords. These terms are often taken for granted by those in the industry, but truly understanding what these phrases mean is a huge step to ensuring that you are leveraging the appropriate solutions with the right product fit.

One such term is the idea of type safety . Type safety is a phrase that often gets used as a sort of asterisk – a solution will note whether or not it is type safe in a brief offhanded mention. The reality is, however, that type safety is one of the most crucial and useful features that a development platform could offer.

Why is this true? Today, we’re going to show you exactly why. In this piece, we’ll talk about types and type safety, and we’ll look at how this solution impacts development in practice.

What’s Your Type?

Before we get into safety, we should first define exactly what a “type” is in this context. “Type” refers to a classification of data which denotes the operations which can be performed upon that data and the behaviors associated with that type. To put it simply, setting the type of a piece of data allows you to know exactly how you can interact with it and how it relates to the rest of the system.

In its most primitive form, a type could be something as simple as an integer or a number.

type User = {
  age: number;

This is exactly what it says on the tin – the type is a simple number like 27. This number has a set interaction paradigm that defines how it can be used or referenced. Regardless of the language or implementation, a type safe solution will result in data types, such as a character data type, interacting fundamentally different than an integer, a number, etc. Foundationally, in type safe solutions, these are very different things with very different uses that are separated on purpose.

As a very simple example, imagine we are creating a piece of code to record visitor information for an art exhibit. It might look something like this:

type User = {
  name: string;
  age: number;
  birthdate: string;
  isMember: boolean;

In this case, our data is quite simple – we use string to record a name, number to record an age, another string to record one’s birthdate, and then a true or false boolean to record whether the attendee is a member of the backing organization for the purposes of rewards clubs and discounts.

This is a very simple set of user data, but more complex types do exist – for instance, arrays, classes, unions, and so forth are themselves types of data that have their own defined purpose and form as well as distinct ways in which they can be interacted with.

Type Safety - Enforcing the Law

Where this gets complicated is when types are not abundantly clear or well-defined. For instance, if you are trying to compile a piece of code that references the date as a tuplet of integers, but the date is instead stored as a string, this code may fail, introduce errors in processing, or even cause the compiling process to fail in its entirety.

// Incorrectly defined date as a string
let date: string = "2024-02-19";

 // Function expecting a tuplet of integers for date processing
 function processDate(year: number, month: number, day: number): void {

    console.log(`Processing date: ${year}-${month}-${day}`);


// Uncommenting the following line would result in a compilation error
// processDate(date); // Error: Argument of type 'string' is not assignable to parameter of type 'number'

This is where the idea of type safety comes in. Type safety is a property of a system which ensures that only the behaviors or actions that are allowed for a specific type are permitted upon that type.

A good way to think about type safety is to imagine having a coding partner who has perfectly memorized your code and can help identify ways in which you use that code illegally. This partner has an entire book of rules pertaining to your system, and can help you identify issues with your particular revision to that code before it becomes a big problem.

As you’re creating your new application, you might find yourself forgetful about the very specific way you implemented user profile IDs. Were they stored as a string? Are they a unique integer? Are they multiple variables combined – like an automatically incrementing integer paired with a country code string?

The good news is that with type safety, you don’t really have to know that – when you create your code, a type safe system will look at how you have implemented that function and will raise a flag if you are interacting with it in a way that is illegal. When it detects such an action, it will let you know how to resolve the issue to satisfy the rules of the system you have created.

Benefits of Type Safety

Type safety grants adoptees some pretty significant benefits.

Firstly, type safety tends to lead to safer and more stable code. Because you are defining a specific way to interact with your data, you are enforcing a stability throughout the system that is hard to do manually. In essence, you can’t use a knife like a fork, and you can’t use a car like a bathtub – type safety makes sure that you’re using parts of the codebase appropriately for their form and function.

Secondly, this approach tends to lead to increased security. By enforcing specific types for your data, you are more introspective about just what that data is being used for – this can help you identify potential security concerns or places where data should not be exposed.

Type safety also typically leads to more sustainable, maintainable, and productive development processes. Since less time is spent fixing mistakes as a result of enforced code types, you tend to see better outcomes over time with more efficient use of resources and queries.


That being said, there are some considerations you should make before adopting type safety. Exactly where this type safety process comes into play is a big variable for making sure your system is useful without being a blocker. A lot of type safety solutions utilize runtime type safety – these solutions implement type safety as the code is run after it has already been compiled.

The problem is that this is allowing the issue to be codified and implemented before notifying the developer of the issue. Runtime type safety is a bit like a person telling you that the brakes are cut on your car when you’re already speeding down the road – helpful context, but not all that useful in isolation.

For this reason, pairing runtime with full static type safety – that is, type safety that occurs at the compile time without relying on runtime checks – is a preferred option, as it allows you to build type safety into your development pipeline without surfacing the issues in a build, whether that build is production or testing.

Genezio to the Rescue!

Type safety is a huge part of what makes Genezio truly powerful. Genezio is a cloud platform that unlocks incredible features for full-stack developers wanting to build scalable and efficient backends with powerful and seamless frontends. By offering a type safe platform for iteration and development , Genezio unlocks a variety of workflows ranging from web applications to LLM-driven applications .

Notably, Genezio offers both runtime and full static type safety. The pairing of both solutions means that you can ensure the client and server communication is consistently aligned, resulting in a more stable, more secure, and more consistent stack.

Type safety is reliable, robust, powerful, and efficient – and it can be leveraged in mere moments by integrating with Genezio. Getting started has never been easier – if you’d like to deploy type safety on your service today, all you have to do is create an account and get building!

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