go in terms of spawn

go.ts

import type { Operation, Task, Result, Port } from "https://deno.land/x/effection/mod.ts";
import { action, spawn, createContext  } from "https://deno.land/x/effection/mod.ts";

const ErrorContext = createContext<Port<Error, never>>("error");

export function* go<T>(op: () => Operation<T>): Operation<Task<Result<T>>> {
  return yield* spawn(function*() {
    try {
      return Ok(yield* call(op));
    } catch (error) {
      let { send } = yield* ErrorContext;
      yield* send(error);
      return Err(error);
    }
  });
}

function call<T>(op: () => Operation<T>): Operation<T> {
  return action(function*(resolve) {
    resolve(yield* op());
  })
}

function Ok<T>(value: T): Result<T> {
  return { type: "resolved", value };
}

function Err<T>(error: Error): Result<T> {
  return { type: "rejected", error };
}