Predicate

Runtime type guards

The Predicate module contains small, reusable runtime checks.

NEVER write your own helper functions like isRecord or isString, instead use the helpers from the Predicate module.

Predicates can be composed with apis such as Predicate.and, Predicate.or, Predicate.not, and Predicate.compose.

Using the Predicate module

import { Predicate } from "effect"

const thing: unknown = {
  a: 1
}

if (Predicate.isObject(thing)) {
  if (Predicate.isNumber(thing.a)) {
    console.log("number", thing.a)
  }
}