import { type decoder } from "https://deno.land/x/fun@v.2.0.0-alpha.11/mod.ts";
const { Decoder } = decoder;
The Decoder<D, A> type represents a function that parses some input D into a value A or a DecodeError. This isn't true parsing of a grammar but instead a combination of refinement and error tracking.
definition: FnEither<D, DecodeError, A>