Using List, Map, and Other ReScript Types from TypeScript

Learn how to effectively use ReScript-specific types like `list` and `char` in your TypeScript project, including best practices for interoperation and efficient coding strategies.
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How to Use List, Map, and Other ReScript Types from TypeScript

In a world where developers often combine multiple programming languages to leverage their unique features, you might find yourself working with a ReScript and TypeScript project. If you've tried to integrate these two, you may have encountered challenges, particularly around using specific ReScript types such as list and map in TypeScript. This guide will guide you through the process of utilizing ReScript's advanced types in a TypeScript environment, ensuring smooth interoperability and efficient coding practices.

The Challenge

When working with a ReScript and TypeScript project, one of the most common hurdles developers face is accessing ReScript-specific types from TypeScript. While basic types like strings and booleans can be easily shared, more complex types like list, char, and map present unique obstacles. In this post, we will explore how to efficiently utilize these types in TypeScript and discuss alternative strategies for dealing with limitations.

Proposed Solutions

Understanding ReScript to JavaScript Compilation

First, it is important to understand that ReScript compiles down to JavaScript. The generated code is often readable, making it easier for developers familiar with JavaScript to understand how the ReScript types map to JavaScript structures.

Example: Consider the following ReScript syntax for creating a list and mapping over it:

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This compiles into a straightforward JavaScript object:

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Use List Construction Functions

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This translates nicely to:

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Implementing Pattern Matching

While executing pattern matching, keep in mind that it’s more straightforward in ReScript. Consider a simple sum function:

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This can be compiled down to JavaScript:

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This way, you can maintain functionality without needing complex manipulations in TypeScript.

Handling Maps with Belt Library

When using the Belt.Map objects, the compilation is generally uncomplicated. Here’s how you can define and use a map in ReScript:

[[See Video to Reveal this Text or Code Snippet]]

The output in JavaScript is fairly straightforward:

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Creating an Interop Module

While you may find the direct use of these types cumbersome, establishing a dedicated interop module could offer a cleaner way to handle TypeScript interactions. This module should ideally convert all ReScript types to more standard JavaScript-friendly types before exposing them to TypeScript.

Export simple types: Keep your exported functions in ReScript limited to basic data types.

Convert lists to arrays: This is simple and helps maintain clarity for TypeScript consumers.

Conclusion

Integrating ReScript types into a TypeScript project doesn’t have to be an overwhelming task. By understanding how ReScript compiles to JavaScript and using the appropriate mapping and construction functions, you can easily work with types like list and map. Furthermore, by creating a dedicated interop module, you can maintain an efficient separation between your ReScript and TypeScript code, improving both clarity and manageability.

With the right approach, leveraging unique features from both languages can significantly enrich your project and lead