Hi I need some guidance on how to employ `Either` while comp

Question

Hi I need some guidance on how to employ `Either` while completing related operations for example i am calling `retrofit` api calls then persisting the data into my local `sqlite` database i am employing `io arrow kt arrow core retrofit` for my `retrofit` calls as follows ` ` ` <https api discogs com artists 45467>` ` ` ` ` ` GET artists artist id ` `suspend fun artist Header HEADER AUTHORISATION accessToken String = ACCESS TOKEN Path artist id artistId Long Either lt CallError ArtistResponse gt ` then in my worker `override suspend fun doActualWork Result ` `return repository` ` artist artistId = 45467 ` ` fold ` `ifLeft = callError gt consumeCallError callError ` `ifRight = ` `val artist = ARTIST MAPPER map it ` `println artist ` `repository database artistDao insertAsync artist ` `Result success ` ` ` ` ` how can wrap or employ Either for the code i execute in my ifRight block above e g the database insert As I am using Room and it does not accept Either type

simon.vergauwen · Answer

Hey < Tower Guidev2> Can you share a complete example in a `text snippet` It shard to follow the code here since I am not sure about the other signatures There are some good docs on Either and Effect here Hope that helps If not I d be happy to help you if you could provide a more complete example I m not sure I understood the problem correctly

Tower Guidev2 · Answer

< simon vergauwen> thanks for taking the time to look at my issue its tricky to share my code what i am trying to achieve is to be able to call a sequence of functions and have them fail fast for example ```fun manageMultipleCalls val stage1 Either lt Bad1 Good1 gt = service call val stage2 Either lt Bad2 Good2 gt = database call stage1 good1 val stage3 Either lt Bad3 Good3 gt = somethingElse call stage2 good2 ``` when any stage throws an exception i need to log the exception details and stop processing further calls do i have to add if when statements after each stage to check isLeft isRight is there a better approach

Tower Guidev2 · Answer

I have refactored my code to the following ```override suspend fun doActualWork Result = repository artist artistId = 45467L fold ifLeft = callError gt consumeCallError callError ifRight = artistResponse gt when val result = Either catch repository database artistDao insertAsync ARTIST MAPPER map artistResponse is Either Left gt consumeDatabaseError result value is Either Right gt Result success ``` which is fine in this case as i only have two calls to contend with e g the `repository artist` retrofit call and the database `repository database artistDao insertAsync ` call however if i had three calls to process in sequence its going to start to get messy

simon.vergauwen · Answer

gt what i am trying to achieve is to be able to call a sequence of functions and have them fail fast gt when any stage throws an exception i need to log the exception details and stop processing further calls Okay that is a very common use case which is normally handled like this ```either lt Throwable Result gt val x Int = Either catch throwing code returning Int tapLeft throwable gt log bind exits either if Left ```

Tower Guidev2 · Answer

thanks can you achieve similar with `effect ` is one approach better than the other

simon.vergauwen · Answer

This uses `effect` under the hood if you re using latest Arrow version since `either ` is `effect toEither ` Where `toEither ` is `fold Either Left it Either Right it ` So one approach is not better as the other it depends on your use case slightly smiling face

Tower Guidev2 · Answer

Im using ```api platform io arrow kt arrow stack 1 1 3 alpha 41 api io arrow kt arrow core api io arrow kt arrow core retrofit ```

Tower Guidev2 · Answer

i ended up with this code

Tower Guidev2 · Answer

```override suspend fun doActualWork Result = when actualWork 45467L is Either Left gt Result failure is Either Right gt Result success private suspend fun actualWork artistId Long = either val artistResponse = repository artist artistId = artistId tapLeft networkError gt consumeNetworkError networkError bind Either catch repository database artistDao insertAsync ARTIST MAPPER map artistResponse tapLeft databaseError gt consumeDatabaseError databaseError bind ```