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Quickstart

Get KAP running in 5 minutes.

1. Add the dependency

dependencies {
    implementation("io.github.damian-rafael-lattenero:kap-core:2.3.0")
}

dependencies {
    implementation 'io.github.damian-rafael-lattenero:kap-core:2.3.0'
}

<dependency>
    <groupId>io.github.damian-rafael-lattenero</groupId>
    <artifactId>kap-core-jvm</artifactId>
    <version>2.3.0</version>
</dependency>

2. Write your first parallel call

import kap.*

data class Dashboard(val user: String, val cart: String, val promos: String)

suspend fun main() {
    val result = Async {
        kap(::Dashboard)
            .with { fetchUser() }     // ┐ all three in parallel
            .with { fetchCart() }      // │ total time = max(individual)
            .with { fetchPromos() }    // ┘ not sum
    }
    println(result) // Dashboard(user=Alice, cart=3 items, promos=SAVE20)
}

suspend fun fetchUser(): String { /* ... */ return "Alice" }
suspend fun fetchCart(): String { /* ... */ return "3 items" }
suspend fun fetchPromos(): String { /* ... */ return "SAVE20" }

That's it. Three calls run in parallel, results are type-checked into your data class.

3. Add phases

Real-world flows have dependencies. Use .then for barriers:

val checkout = Async {
    kap(::CheckoutResult)
        .with { fetchUser() }           // ┐ phase 1: parallel
        .with { fetchCart() }            // ┘
        .then { validateStock() }        // ── phase 2: waits for phase 1
        .with { calcShipping() }         // ┐ phase 3: parallel
        .with { calcTax() }              // ┘
}

.with = parallel. .then = barrier. The code shape is the execution plan.

4. Use value-dependent phases

When phase 2 needs phase 1's result, use .andThen:

val dashboard = Async {
    kap(::UserContext)
        .with { fetchProfile(userId) }      // ┐ phase 1
        .with { fetchPreferences(userId) }   // ┘
        .andThen { ctx ->                    // ── barrier: ctx available
            kap(::EnrichedDashboard)
                .with { fetchRecommendations(ctx.profile) }  // ┐ phase 2
                .with { fetchPromotions(ctx.tier) }           // ┘
        }
}

5. Run an example

git clone https://github.com/damian-rafael-lattenero/kap.git
cd kap
./gradlew :examples:ecommerce-checkout:run

What's next?