@typed/io/source/guard/Guard.ts

Runtime IO type system

import { curry, Is } from '@typed/lambda'

export interface Guard<A = any> {
  readonly is: Is<A>
}

export namespace Guard {
  export const is = <A>(is: Is<A>): Guard<A> => ({ is })
}

export type TypeOf<A> = A extends Guard<infer R> ? R : never

export const guard = curry(__guard) as {
  <A>(guard: Guard<A>, value: unknown): value is A
  <A>(guard: Guard<A>): Is<A>
}

function __guard<A>(guard: Guard<A>, value: unknown) {
  return guard.is(value)
}