Reading Valibot Thesis

Quick notes on things I found interesting or useful in the Valibot thesis “Implementation of a modular schema library in TypeScript with focus on bundle size and performance”.

Thesis Source: https://valibot.dev/thesis.pdf

Chapter 1. Introduction

• Impressive growth rate of Zod: 525% in 12 months.
• The way Zod is written (OOP, builder pattern, etc.) is not suitable for tree-shaking, causing a bundle size issue.
• The primary goal of Valibot is to reduce the bundle size.

Chapter 2. Fundamentals

• Common use cases of schema validation:
  • Server Requests
  • Browser State, like search parameters, cookies, client storage, etc.
  • Form Validation
  • Config Files
  • …
• An interesting mental model for bundle size optimization:
  • Tree Shaking
  • Code Splitting
  • Minification
  • Compression

Chapter 3. Research

• Repeated patterns increase the compression rate.
• Object spread operator could cause exponential increase in validation time.
• Throwing unnecessary internal Error objects causes overhead since they captures additional information.

Chapter 4. Results

This part describes part of the design of Valibot and some comparisons with other existing libraries.

At initialization:

• Valibot schemas only return objects containing metadata and an internal _parse function.

  • export type BaseSchema<TInput = any, TOutput = TInput> = {
      async: false
      _parse(input: unknown, info?: ParseInfo): _ParseResult<TOutput>
      _types?: { input: TInput; output: TOutput }
    }

• And actions return a closure which captures the passed requirements and have the same signature with schemas.

At validation:

• Validation entries: parse, safeParse of is using a schema.
• _parse is called with the input value and finally returns a discriminated union of the result or the error.

Chapter 5. Conclusion

Improvements:

• Tree shakable because of modular design.
• Bundle size: 55% of Zod’s size.
• Performance:
  • Initialization: 5% of Zod’s time.
  • Validation:
    • Successful validation: 55% of Zod’s time.
    • Erroneous validation: 49% of Zod’s time.

Worse parts:

• Tooling: Needs IDE extensions for better developer experience.