Parallel IO🔗

One of the most powerful uses of tasks is running multiple IO operations at the same time.

def runParallel : IO Unit := do
  let t1 ← IO.asTask do
    IO.sleep 1000
    return "A"
  let t2 ← IO.asTask do
    IO.sleep 1000
    return "B"
  
  IO.println "Waiting for both tasks..."
  let r1 ← IO.wait t1
  let r2 ← IO.wait t2
  
  IO.println s!"Results: T₁ = {r1.toOption.getD ""}, 
    T₂ = {r2.toOption.getD ""}"

In this example, the total wait time is approximately 1 second, even though we performed two 1-second sleeps, because they ran in parallel.