effect-io-ai

Package: effect
Module: Schema

Schema.asserts

Creates an assertion function that throws an error if the input does not match the schema.

When to use

Use to validate unknown input at runtime while narrowing the value with a TypeScript assertion signature.

Details

The input is narrowed if the assertion succeeds. If schema validation fails, the assertion throws an Error whose cause is SchemaIssue.Issue.

Gotchas

Causes that contain defects, interruptions, or other non-schema reasons throw with the underlying Cause attached instead of being converted to schema validation errors.

Example (Asserting and narrowing an input)

import { Schema } from "effect"

const input: unknown = "hello"

// This will pass silently (no return value) and narrow input to string
Schema.asserts(Schema.String, input)
console.log(input.toUpperCase())

// This will throw an error
try {
  const invalid: unknown = 123
  Schema.asserts(Schema.String, invalid)
} catch (error) {
  console.log("Non-string assertion failed as expected")
}

Signature

declare const asserts: <S extends Constraint, I>(schema: S, input: I) => asserts input is I & S["Type"]

Source

Since v4.0.0