progress with futures

tests/parallel/tflowvar.nim

@@ -0,0 +1,17 @@
+discard """
+  output: '''foobarfoobarbazbearbazbear'''
+  cmd: "nimrod $target --threads:on $options $file"
+"""
+
+import threadpool
+
+proc computeSomething(a, b: string): string = a & b & a & b
+
+proc main =
+  let fvA = spawn computeSomething("foo", "bar")
+  let fvB = spawn computeSomething("baz", "bear")
+
+  echo(^fvA, ^fvB)
+
+main()
+sync()