Type Guard is a lightweight PHP library that allows you to narrow down the type of an variable to a more specific type.
Comply is a tiny library to help you define policies in your app
Combine user-defined type guards / type predicates as unions and intersections.
Collection of validation functions for JavaScript data
TypeScript library with additional utility types and predicators generation
Check if an string or number is compatible to an TypeScript enum structure
Sample project for "String Literal Type Guard in TypeScript" blogpost
Just function to predicate non nullable with type guard.