ArkType is a new runtime validator for TypeScript and the first library with the goal of making type syntax available 1:1 in JS with no compilation step.

It uses a carefully optimized static parser so that with each character you type, you'll see a list of completions, a clear ParseError, or your inferred type. At runtime, a simple definition like "string|number[]" will be transformed into a TypeNode that can be used to validate or transform inputs, compared to other TypeNodes, or combined with other definitions to form new TypeNodes.

This talk will cover the process of building ArkType, with a focus on the type-level parser and runtime type system, and demo some of the most exciting features like scopes, index signatures and generics.