Catch Error Experiment

catchErrorExperiment.ts

import { flow, pipe } from 'fp-ts/function';
import * as E from 'fp-ts/Either'
import * as r from 'rxjs'
import * as ro from 'rxjs/operators'
import * as OB from 'fp-ts-rxjs/lib/Observable'

export const tryCatch = <E, A>(
  onErr: (e: unknown) => E
): r.OperatorFunction<A, E.Either<E, A>> => flow(
  OB.map(E.right),
  ro.catchError(flow(onErr, E.left, OB.of))
);

const exceptionOnError = (a: unknown) => {
  throw new Error('new error')
}

const a = pipe(
  r.throwError(new Error('original error')),
  tryCatch(exceptionOnError),
)
a.subscribe((e) => {
  console.log(JSON.stringify(e))
}, (error) => {
  console.log(`caught by observable: ${(error as Error).message}`)
})
// output:
// caught by observable: new error