Is there a brief syntax for executing a block n times in Scala?

Question

I find myself writing code like this when I want to repeat some execution n times:

for (i <- 1 to n) { doSomething() }

I\'m looking for

Answer 1

With scalaz 5:

doSomething.replicateM[List](n)

With scalaz 6:

n times doSomething

And that works as you would expect with most types (more precisely, for every monoid):

scala> import scalaz._; import Scalaz._; import effects._;
import scalaz._
import Scalaz._
import effects._

scala> 5 times "foo"
res0: java.lang.String = foofoofoofoofoo

scala> 5 times List(1,2)
res1: List[Int] = List(1, 2, 1, 2, 1, 2, 1, 2, 1, 2)

scala> 5 times 10
res2: Int = 50

scala> 5 times ((x: Int) => x + 1).endo
res3: scalaz.Endo[Int] = 

scala> res3(10)
res4: Int = 15

scala> 5 times putStrLn("Hello, World!")
res5: scalaz.effects.IO[Unit] = scalaz.effects.IO$$anon$2@36659c23

scala> res5.unsafePerformIO
Hello, World!
Hello, World!
Hello, World!
Hello, World!
Hello, World!

You could also say doSomething replicateM_ 5 which only works if your doSomething is an idiomatic value (see Applicative). It has better type-safety, since you can do this:

scala> putStrLn("Foo") replicateM_ 5
res6: scalaz.effects.IO[Unit] = scalaz.effects.IO$$anon$2@8fe8ee7

but not this:

scala> { System.exit(0) } replicateM_ 5
:15: error: value replicateM_ is not a member of Unit

Let me see you pull that off in Ruby.