sets in typed vs fields

gistfile1.scala

scala> TypedPipe.from((0 until 10).toList).groupAll.size.dump
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell] starting
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell]  source: MemoryTap["NullScheme"]["0.6803924901219981"]
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell]  sink: MemoryTap["NullScheme"]["0.3895948780547176"]
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell]  parallel execution is enabled: true
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell]  starting jobs: 1
14/07/26 21:58:42 INFO flow.Flow: [ScaldingShell]  allocating threads: 1
14/07/26 21:58:42 INFO flow.FlowStep: [ScaldingShell] starting step: local
((),10)

scala> TypedPipe.from((0 until 10).toSet).groupAll.size.dump
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell] starting
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell]  source: MemoryTap["NullScheme"]["0.2681900590184605"]
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell]  sink: MemoryTap["NullScheme"]["0.6702092691249959"]
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell]  parallel execution is enabled: true
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell]  starting jobs: 1
14/07/26 21:58:48 INFO flow.Flow: [ScaldingShell]  allocating threads: 1
14/07/26 21:58:48 INFO flow.FlowStep: [ScaldingShell] starting step: local
((),1)

scala> IterableSource((0 until 10).toSet, 'a).read.toTypedPipe[Int]('a).groupAll.size.dump
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell] starting
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell]  source: MemoryTap["NullScheme"]["0.4200594268446092"]
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell]  sink: MemoryTap["NullScheme"]["0.8554432259895711"]
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell]  parallel execution is enabled: true
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell]  starting jobs: 1
14/07/26 22:03:58 INFO flow.Flow: [ScaldingShell]  allocating threads: 1
14/07/26 22:03:58 INFO flow.FlowStep: [ScaldingShell] starting step: local
((),10)