Add some words about Compose

[serras]

This section makes it more visible that Arrow is a great companion for Compose, and helps combat the impression that Arrow may be "backend-oriented".

[raulraja]

Looks great!, thanks @serras , Are there any patterns where Raise is useful with compose for error / success display? Perhaps we can include something there too.

[serras]

Looks great!, thanks @serras , Are there any patterns where Raise is useful with compose for error / success display? Perhaps we can include something there too.

I've tried to think about an example, but I couldn't find a good one for this case, as opposed to something like a circuit breaker or optics. Do you have any in mind?

[raulraja]

Looks great!, thanks @serras , Are there any patterns where Raise is useful with compose for error / success display? Perhaps we can include something there too.

I've tried to think about an example, but I couldn't find a good one for this case, as opposed to something like a circuit breaker or optics. Do you have any in mind?

I was thinking about something like:

import androidx.compose.desktop.ui.tooling.preview.Preview
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Text
import androidx.compose.runtime.*
import androidx.compose.ui.window.Window
import androidx.compose.ui.window.application
import arrow.core.raise.Raise
import arrow.core.raise.either
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch

// Error types
sealed class ErrorType
object UserNotFound : ErrorType()
object NetworkError : ErrorType()

// Data class for User Profile
data class UserProfile(val id: String, val name: String)

// Sample function to fetch user profile
suspend fun Raise<ErrorType>.fetchUserProfile(userId: String): UserProfile {
  delay(3000)
  // Here, you would implement actual logic to fetch the user profile
  // For demonstration, let's assume the user is not found
  raise(UserNotFound)
}

// Main Composable Function
@Composable
fun UserProfileScreen() {
  val coroutineScope = rememberCoroutineScope()
  var userProfile by remember { mutableStateOf<UserProfile?>(null) }
  var error by remember { mutableStateOf<ErrorType?>(null) }

  // Simulate fetch user profile
  coroutineScope.launch {
    either {
      fetchUserProfile("123")
    }.fold(
      ifLeft = { errorType ->
        error = errorType
      },
      ifRight = { profile ->
        userProfile = profile
      }
    )
  }

  when {
    userProfile != null -> Text("User: ${userProfile!!.name}")
    error is UserNotFound -> Text("User not found")
    error is NetworkError -> Text("Network error. Please try again.")
    else -> Text("Loading...")
  }
}


@Composable
@Preview
fun App() {
  MaterialTheme {
    UserProfileScreen()
  }
}

fun main() = application {
  Window(onCloseRequest = ::exitApplication) {
    App()
  }
}

But I don't know if this is considered a good pattern in Compose.

[serras]

@raulraja I've added a few words about Either and Ior, which I think it's the part most developer can immediately understand. I think the Raise DSL requires some additional investment, so I've added it at the end of the section. WDYT?

[serras]

I've added some additional documentation in relation to arrow-kt/arrow#3299