Go and Elixir progrmas

Author: rtoal

elixir/old_school_primes.exs

@@ -1,6 +1,6 @@
 # A line by line translation of the Erlang version
 defmodule Primes do
-  def main(_args) do
+  def main() do
     max = 1000
 
     2..max
@@ -37,4 +37,4 @@ defmodule Primes do
   end
 end
 
-Primes.main(System.argv())
+Primes.main()

elixir/primes.exs

@@ -1,13 +1,5 @@
 defmodule Primes do
-  def main(_args) do
-    2..1000
-    |> Task.async_stream(
-        &print_if_prime/1,
-        max_concurrency: System.schedulers_online())
-    |> Stream.run()
-  end
-
-  defp print_if_prime(n) do
+  def print_if_prime(n) do
     if is_prime?(n), do: IO.write("#{n} ")
   end
 
@@ -20,4 +12,9 @@ defmodule Primes do
   end
 end
 
-Primes.main(System.argv())
+2..1000
+|> Task.async_stream(
+    &Primes.print_if_prime/1,
+    max_concurrency: System.schedulers_online(),
+    ordered: false)
+|> Stream.run()

go/simple_primes.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+)
+
+func main() {
+	max := 1000
+	var wg sync.WaitGroup
+	for n := 2; n <= max; n++ {
+		wg.Add(1)
+		go func(n int) {
+			defer wg.Done()
+			if isPrime(n) {
+				fmt.Printf("%d ", n)
+			}
+		}(n)
+	}
+	wg.Wait()
+}
+
+func isPrime(n int) bool {
+	if n == 2 || n == 3 {
+		return true
+	}
+	if n <= 1 || n%2 == 0 || n%3 == 0 {
+		return false
+	}
+	for i := 5; i*i <= n; i += 6 {
+		if n%i == 0 || n%(i+2) == 0 {
+			return false
+		}
+	}
+	return true
+}