test +RTS -stest1ps.stat 
552,632,612 bytes allocated in the heap
 96,049,260 bytes copied during GC (scavenged)
 82,350,516 bytes copied during GC (not scavenged)
 38,016,248 bytes maximum residency (7 sample(s))

       1061 collections in generation 0 (  0.66s)
          7 collections in generation 1 (  0.92s)

         74 Mb total memory in use

  INIT  time    0.02s  (  0.00s elapsed)
  MUT   time    2.21s  (  2.20s elapsed)
  GC    time    1.58s  (  1.47s elapsed)
  EXIT  time    0.00s  (  0.00s elapsed)
  Total time    3.81s  (  3.67s elapsed)

  %GC time      41.5%  (40.1% elapsed)

  Alloc rate    247,484,376 bytes per MUT second

  Productivity  58.0% of total user, 60.2% of total elapsed