Backend languages

Ruby, Java, Go & C#

Four heavyweight backend languages, side by side. Each has its own philosophy — elegant, enterprise, concurrent, or all-Microsoft — and its own idiomatic style.

Demo 01

One task, four languages

The same little program — greet the world and sum some numbers — written idiomatically in each. Switch tabs, read the real code, then press Run to see the simulated output (these compile on a server, not in your browser).

# hello.rb — run with: ruby hello.rb
nums = [1, 2, 3, 4, 5]
puts "Hello from Ruby!"
nums.each { |n| puts "  n = #{n}" }
puts "sum = #{nums.sum}"

// Hello.java — javac Hello.java && java Hello
public class Hello {
  public static void main(String[] args) {
    int[] nums = {1, 2, 3, 4, 5};
    System.out.println("Hello from Java!");
    int sum = 0;
    for (int n : nums) { System.out.println("  n = " + n); sum += n; }
    System.out.println("sum = " + sum);
  }
}

// main.go — run with: go run main.go
package main

import "fmt"

func main() {
    nums := []int{1, 2, 3, 4, 5}
    fmt.Println("Hello from Go!")
    sum := 0
    for _, n := range nums {
        fmt.Printf("  n = %d\n", n)
        sum += n
    }
    fmt.Printf("sum = %d\n", sum)
}

// Program.cs — run with: dotnet run
var nums = new[] { 1, 2, 3, 4, 5 };
Console.WriteLine("Hello from C#!");
int sum = 0;
foreach (var n in nums) {
    Console.WriteLine($"  n = {n}");
    sum += n;
}
Console.WriteLine($"sum = {sum}");

// output appears here

Demo 02

Go goroutines: 1,000 tasks at once

Go's superpower is cheap concurrency. A goroutine is a lightweight thread — you can launch thousands. Press Launch and watch 1,000 tasks light up (cyan = running) and finish (green). The grid is a simulation of Go's scheduler.

var wg sync.WaitGroup
for i := 0; i < 1000; i++ {
    wg.Add(1)
    go func(id int) {       // ← launch a goroutine
        defer wg.Done()
        process(id)
    }(i)
}
wg.Wait()                       // block until all 1000 finish

running now

completed

~2 KB

stack per goroutine (vs ~1 MB per OS thread)

Demo 03

Each language, in one line

Why pick one over another? A quick orientation.

Ruby

Developer happiness & elegance — powers Rails.

Java

Rock-solid, JVM, enterprise & Android backends.

Fast, simple, built for concurrency & the cloud.

Microsoft's flagship — .NET, games (Unity), web.

The code in every tab is real, idiomatic Ruby, Java, Go and C#. But these are compiled / server-side languages that can't run in a browser — so the program output and the 1,000-goroutine concurrency grid are an interactive simulation written in vanilla JavaScript. The shared CSS shell provides the page styling.

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