Comparing the use of foreach loop without lambdas and the use of a pipeline
(such as ....map(..->...).reduce(..->...)) with lambdas and the resulting
sequential versus concurrent behavior in different programming languages
Java, Js, C# and Kotlin.
Full article here: Stretching Async/Await With Lambdas
async function fetchAndSum(...urls) {
let sum = 0
for (const url of urls) {
console.log(`FETCHING from ${url}`)
const res = await fetch(url)
const body = await res.text()
console.log(`=======> from ${url}`)
sum += body.length
}
return sum
} |
async function fetchAndSumλ(...urls) {
return urls
.map(async (url, i) => {
console.log(`FETCHING from ${url}`)
const resp = await fetch(url)
const body = await resp.text()
const length = body.length
console.log(`=======> from ${urls[i]}`)
return length
})
.reduce(async (prev, curr) => await prev + await curr)
} |
|
|
static async Task<int> FetchAndSum(string[] urls) {
int sum = 0;
using(HttpClient httpClient = new HttpClient()) {
foreach(var url in urls) {
Console.WriteLine($"FETCHING from {url}");
var body = await httpClient.GetStringAsync(url);
Console.WriteLine($"=======> from {url}");
sum += body.Length;
}
}
return sum;
} |
static async Task<int> FetchAndSumλ(string[] urls) {
using(HttpClient httpClient = new HttpClient()) {
return await urls
.Select(async url => {
Console.WriteLine($"FETCHING from {url}");
var body = await httpClient.GetStringAsync(url);
Console.WriteLine($"=======> from {url}");
return body.Length;
})
.Aggregate(async (prev, curr) => await prev + await curr);
}
} |
|
|
suspend fun fetchAndSum(vararg urls: String): Int {
var sum = 0
for (url in urls) {
println("FETCHING from $url")
val resp = httpClient
.sendAsync(request(url), BodyHandlers.ofString())
.await()
println("=======> from $url")
sum = sum + resp.body().length
}
return sum
} |
suspend fun CoroutineScope.fetchAndSumλ(vararg urls: String): Int {
return urls
.asSequence()
.map { url -> async {
println("FETCHING from $url")
val resp = httpClient
.sendAsync(request(url), BodyHandlers.ofString())
.await()
println("=======> from $url")
resp.body().length
}}
.reduce { prev, curr -> async {
prev.await() + curr.await()
}}
.await();
} |
|
|