Arrow fx coroutine play on Chuck Norris facts

build.gradle

plugins {
    id 'org.jetbrains.kotlin.jvm' version '1.4.10'
}

apply plugin: 'kotlin-kapt'

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
    jcenter()
    maven { url "https://dl.bintray.com/arrow-kt/arrow-kt/" }
    maven { url 'https://oss.jfrog.org/artifactory/oss-snapshot-local/' } // for SNAPSHOT builds
}

def arrow_version = "0.11.0"
def fuel_version = "2.3.0"
dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib"
    implementation "io.arrow-kt:arrow-core:$arrow_version"
    implementation "io.arrow-kt:arrow-fx:$arrow_version"
    implementation "io.arrow-kt:arrow-fx-coroutines:$arrow_version"
    implementation "io.arrow-kt:arrow-optics:$arrow_version"
    implementation "io.arrow-kt:arrow-syntax:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"

    implementation "com.github.kittinunf.fuel:fuel:$fuel_version"
    implementation "com.github.kittinunf.fuel:fuel-jackson:$fuel_version"
    implementation "com.github.kittinunf.fuel:fuel-coroutines:$fuel_version"

    implementation "com.fasterxml.jackson.module:jackson-module-kotlin:2.11.+"
}

tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
    kotlinOptions {
        jvmTarget = "1.8"
    }
}

main.kt

import arrow.core.*
import arrow.core.extensions.either.applicative.applicative
import arrow.core.extensions.either.applicative.map
import arrow.core.extensions.list.traverse.sequence
import arrow.core.extensions.listk.functor.functor
import arrow.fx.IODispatchers.IOPool
import arrow.fx.coroutines.ComputationPool
import arrow.fx.coroutines.evalOn
import arrow.fx.coroutines.parTraverse
import arrow.typeclasses.Show
import com.github.kittinunf.fuel.core.awaitResponseResult
import com.github.kittinunf.fuel.httpGet
import com.github.kittinunf.fuel.jackson.jacksonDeserializerOf

suspend fun printThreadName(): Unit =
    println(Thread.currentThread().name)

data class HttpError(val message: String, val cause: Throwable?)

typealias Category = String

suspend fun loadCategories(): Either<HttpError, List<Category>> =
    evalOn(IOPool) {
        val (value, error) = "https://api.chucknorris.io/jokes/categories"
            .httpGet()
            .awaitResponseResult(jacksonDeserializerOf<List<String>>()).third
        printThreadName()
        error
            ?.let { Either.left(HttpError("Error loading categories", it)) }
            ?: Either.right(value!!)
    }

data class Quote(
    val value: String
)

suspend fun loadRandom(category: String): Either<HttpError, Quote> =
    evalOn(IOPool) {
        val (value, error) = "https://api.chucknorris.io/jokes/random?category=$category"
            .httpGet()
            .awaitResponseResult(jacksonDeserializerOf<Quote>()).third
        printThreadName()
        error
            ?.let { Either.left(HttpError("Error loading quote for $category", it)) }
            ?: Either.right(value!!)
    }

suspend fun loadQuotesForCategories(categories: List<Category>): Either<HttpError, List<Pair<Category, Quote>>> =
    run {
        printThreadName()
        categories.parTraverse { category -> loadRandom(category).map { category to it } }
            .sequence(Either.applicative()).map { it.fix() }.fix()
    }

val categoryQuoteShow = object : Show<Pair<Category, Quote>> {
    override fun Pair<Category, Quote>.show(): String =
        "$first -  ${second.value}"
}

val showList = with(categoryQuoteShow) {
    ListK.functor().lift<Pair<Category, Quote>, String> { it.show() }
}

suspend fun main() {
    evalOn(ComputationPool) {
        printThreadName()
        loadCategories()
            .flatMap { loadQuotesForCategories(it) }
            .map { showList.invoke(it.k()).fix() }
            .map {
                printThreadName()
                it.forEach(::println)
            }
    }
}

Output sample

ForkJoinPool-1-worker-19
io-arrow-kt-worker-0
ForkJoinPool-1-worker-19
io-arrow-kt-worker-10
io-arrow-kt-worker-15
io-arrow-kt-worker-13
io-arrow-kt-worker-7
io-arrow-kt-worker-5
io-arrow-kt-worker-1
io-arrow-kt-worker-4
io-arrow-kt-worker-9
io-arrow-kt-worker-12
io-arrow-kt-worker-6
io-arrow-kt-worker-2
io-arrow-kt-worker-11
io-arrow-kt-worker-14
io-arrow-kt-worker-3
io-arrow-kt-worker-8
io-arrow-kt-worker-0
ForkJoinPool-1-worker-23
animal -  Chuck Norris once rode a nine foot grizzly bear through an automatic car wash, instead of taking a shower.
career -  Chuck Norris is actually the front man for Apple. He let's Steve Jobs run the show when he's on a mission. Chuck Norris is always on a mission.
celebrity -  Chuck Norris smells what the Rock is cooking... because the Rock is Chuck Norris' personal chef.
dev -  Chuck Norris does not code in cycles, he codes in strikes.
explicit -  Chuck Norris' penis can bench over 250.
fashion -  Chuck Norris does not follow fashion trends, they follow him. But then he turns around and kicks their ass. Nobody follows Chuck Norris.
food -  For Chuck Norris, there are only two food groups. Steak and beer.
history -  Chuck Norris once shot down a German fighter plane with his finger. By yelling "Bang!"
money -  Well it's-a one for the money, two for the show, three to get ready and BAM!! Chuck Norris.
movie -  Jean-Claude Van Damme once kicked Chuck Norris' ass. He was then awakened from his dream by a roundhouse kick to the face.
music -  Most boots are made for walkin'. Chuck Norris' boots ain't that merciful.
political -  Chuck Norris is widely predicted to be first black president. If you're thinking to yourself, "But Chuck Norris isn't black", then you are dead wrong. And stop being a racist.
religion -  It's widely believed that Jesus was Chuck Norris' stunt double for crucifixion due to the fact that it is impossible for nails to pierce Chuck Norris' skin.
science -  Chuck Norris describes human beings as "a sociable holder for blood and guts".
sport -  Chuck Norris was banned from competitive bullriding after a 1992 exhibition in San Antonio, when he rode the bull 1,346 miles from Texas to Milwaukee Wisconsin to pick up his dry cleaning.
travel -  Chuck Norris did in fact, build Rome in a day.