Extends Monet js functionality

monet_ex.ts

// https://monet.github.io/monet.js/

import { Observable } from 'rxjs';
import { Maybe } from 'monet';
import { filter, map } from 'rxjs/operators';

export function filterIsSome<T extends NonNullable<{}>>() {
  return function (source: Observable<Maybe<T>>): Observable<Maybe<T>> {
    return source.pipe(filter((maybe) => maybe.isSome()));
  };
}

export function filterUnwrapSome<T extends NonNullable<{}>>() {
  return function (source: Observable<Maybe<T>>): Observable<T> {
    return source.pipe(
      filter((maybe) => maybe.isSome()),
      map((maybe) => maybe.some())
    );
  };
}