How to reduce an array of effects (TaskEither)

[florianbepunkt]

How to reduce an array of TaskEithers?

Given an array of effects I would like to reduce them to a single TaskEither, piping the result of each effect into the next one and terminating at the earliest failure

export type PreHook<Command extends AnyCommand, State extends BaseState> = ({
  command,
  state,
}: {
  command: Command;
  state: State;
}) => TE.TaskEither<Std.Error.Err, { command: Command; state: State }>;

// code below is obviously not working, trying to illustrate the goal
const applyPreHooks =
  <Command extends AnyCommand, State extends BaseState>(preHooks: PreHook<Command, State>[]) =>
  ({ command, state }: { command: Command; state: State }) => {
    preHooks.reduce(
      ({ command, state }, hook) => {
        const a = hook({ command, state });

        return { command, state };
      },
      { command, state }
    );
  };

[florianbepunkt]

Okay, the answer is rather simple..

export const applyPreHooks =
  <Command extends AnyCommand, State extends BaseState>(preHooks: PreHook<Command, State>[]) =>
  (initialValues: { command: Command; state: State }) =>
    preHooks.reduce(
      (acc, hook) => TE.chain(hook)(acc),
      TE.of(initialValues) as TE.TaskEither<Std.Error.Err, { command: Command; state: State }>
    );