Created
April 5, 2012 11:33
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use state + traverse
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scala> import scalaz._ | |
import scalaz._ | |
scala> import Scalaz._ | |
import Scalaz._ | |
scala> case class FooState(partialResult: List[Int], result: List[List[Int]]) { | |
| def newPartial(n:Int) = FooState(n::partialResult, result) | |
| def newResult = FooState(List(), partialResult.reverse :: result) | |
| } | |
defined class FooState | |
scala> def nextFooState(n: Option[Int]) = modify( (s:FooState) => n match { | |
| case None => s.newResult | |
| case Some(nn) => s.newPartial(nn) | |
| }) | |
nextFooState: (n: Option[Int])scalaz.package.State[FooState,FooState] | |
scala> def chunks(l: List[Option[Int]]) : List[List[Int]] = { | |
| val initialState = FooState(List(),List()) | |
| val finalState = l.traverseS(nextFooState).exec(initialState).newResult | |
| finalState.result.reverse | |
| } | |
chunks: (l: List[Option[Int]])List[List[Int]] | |
scala> chunks(List(Some(1), Some(2), None, Some(3), Some(4), Some(5), None, Some(6),Some(7))) | |
res0: List[List[Int]] = List(List(1, 2), List(3, 4, 5), List(6, 7)) |
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