Add support for await inside pipe()

[koraa]

It would be nice if await could be used within a pipe.

const doAwait = Symbol();

const pipe = (val, ...fns) => {
  while (fns.length > 0) {
    const fn = fns.shift()
    if (fn === doAwait) {
      return Promise.resolve(val).then((val_) => pipe(val_, ...fns));
    } else {
      val = fn(val);
    }
  }
  return val;
};

This could even be generalized and use a special trait and made to work in compose…

Using a new new function doAwait instead of the normal await is not terribly pretty, but can be done.

[koraa]

Superseeded by #138