Segment
Related Docs:
object Segment
| package fs2
Concatenates this segment with s2.
Concatenates this segment with s2.
scala> (Segment(1,2,3) ++ Segment(4,5,6)).force.toVector res0: Vector[Int] = Vector(1, 2, 3, 4, 5, 6)
Like ++ but allows the result type of s2 to differ from R.
Alias for mapResult( => r2).
Filters and maps simultaneously.
Filters and maps simultaneously.
scala> Segment(Some(1), None, Some(2)).collect { case Some(i) => i }.force.toVector res0: Vector[Int] = Vector(1, 2)
Equivalent to Segment.singleton(o2) ++ this.
Equivalent to Segment.singleton(o2) ++ this.
scala> Segment(1, 2, 3).cons(0).force.toVector res0: Vector[Int] = Vector(0, 1, 2, 3)
Returns a segment that suppresses all output and returns the result of this segment when run.
Returns a segment that suppresses all output and returns the result of this segment when run.
scala> Segment.from(0).take(3).drain.force.run.toOption.get.take(5).force.toVector res0: Vector[Long] = Vector(3, 4, 5, 6, 7)
Filters output elements of this segment with the supplied predicate.
Filters output elements of this segment with the supplied predicate.
scala> Segment(1,2,3,4,5).filter(_ % 2 == 0).force.toVector res0: Vector[Int] = Vector(2, 4)
List-like flatMap, which applies f to each element of the segment and concatenates
the results.
List-like flatMap, which applies f to each element of the segment and concatenates
the results.
scala> Segment(1, 2, 3).flatMap(i => Segment.seq(List.fill(i)(i))).force.toVector res0: Vector[Int] = Vector(1, 2, 2, 3, 3, 3)
Stateful version of flatMap, where the function depends on a state value initialized to
init and updated upon each output.
Stateful version of flatMap, where the function depends on a state value initialized to
init and updated upon each output.
The final state is returned in the result, paired with the result of the source stream.
scala> val src = Segment("Hello", "World", "\n", "From", "Mars").flatMapAccumulate(0)((l,s) => | if (s == "\n") Segment.empty.asResult(0) else Segment((l,s)).asResult(l + s.length)) scala> src.force.toVector res0: Vector[(Int,String)] = Vector((0,Hello), (5,World), (0,From), (4,Mars)) scala> src.drain.force.run res1: (Unit,Int) = ((),8)
Like append but allows to use result to continue the segment.
Flattens a Segment[Segment[O2,R],R] in to a Segment[O2,R].
Flattens a Segment[Segment[O2,R],R] in to a Segment[O2,R].
scala> Segment(Segment(1, 2), Segment(3, 4, 5)).flatten.force.toVector res0: Vector[Int] = Vector(1, 2, 3, 4, 5)
Flattens a Segment[Chunk[O2],R] in to a Segment[O2,R].
Flattens a Segment[Chunk[O2],R] in to a Segment[O2,R].
scala> Segment(Chunk(1, 2), Chunk(3, 4, 5)).flattenChunks.force.toVector res0: Vector[Int] = Vector(1, 2, 3, 4, 5)
Folds the output elements of this segment and returns the result as the result of the returned segment.
Folds the output elements of this segment and returns the result as the result of the returned segment.
scala> Segment(1,2,3,4,5).fold(0)(_ + _).force.run res0: (Unit, Int) = ((),15)
Provides access to operations which force evaluation of some or all elements of this segment.
Returns a segment that outputs all but the last element from the original segment, returning the last element as part of the result.
Returns a segment that outputs all but the last element from the original segment, returning the last element as part of the result.
scala> Segment(1,2,3).last.drain.force.run res0: (Unit, Option[Int]) = ((),Some(3)) scala> Segment(1,2,3).last.force.toList res1: List[Int] = List(1, 2)
Returns a segment that maps each output using the supplied function.
Returns a segment that maps each output using the supplied function.
scala> Segment(1,2,3).map(_ + 1).force.toVector res0: Vector[Int] = Vector(2, 3, 4)
Stateful version of map, where the map function depends on a state value initialized to
init and updated upon each output value.
Stateful version of map, where the map function depends on a state value initialized to
init and updated upon each output value.
The final state is returned in the result, paired with the result of the source stream.
scala> val src = Segment("Hello", "World").mapAccumulate(0)((l,s) => (l + s.length, (l, s))) scala> src.force.toVector res0: Vector[(Int,String)] = Vector((0,Hello), (5,World)) scala> src.drain.force.run res1: (Unit,Int) = ((),10)
Returns a segment that maps each output using the supplied function and concatenates all the results.
Returns a segment that maps each output using the supplied function and concatenates all the results.
scala> Segment(1,2,3).mapConcat(o => Chunk.seq(List.range(0, o))).force.toVector res0: Vector[Int] = Vector(0, 0, 1, 0, 1, 2)
Maps the supplied function over the result of this segment.
Maps the supplied function over the result of this segment.
scala> Segment('a', 'b', 'c').withSize.mapResult { case (_, size) => size }.drain.force.run res0: Long = 3
Equivalent to s2 ++ this.
Equivalent to s2 ++ this.
scala> Segment(1, 2, 3).prepend(Segment(-1, 0)).force.toVector res0: Vector[Int] = Vector(-1, 0, 1, 2, 3)
Like fold but outputs intermediate results.
Like fold but outputs intermediate results. If emitFinal is true, upon reaching the end of the stream, the accumulated
value is output. If emitFinal is false, the accumulated output is not output. Regardless, the accumulated value is
returned as the result of the segment.
scala> Segment(1, 2, 3, 4, 5).scan(0)(_+_).force.toVector res0: Vector[Int] = Vector(0, 1, 3, 6, 10, 15)
Sums the elements of this segment and returns the sum as the segment result.
Sums the elements of this segment and returns the sum as the segment result.
scala> Segment(1, 2, 3, 4, 5).sum.force.run res0: Int = 15
Lazily takes n elements from this segment.
Lazily takes n elements from this segment. The result of the returned segment is either a left
containing the result of the original segment and the number of elements remaining to take when
the end of the source segment was reached, or a right containing the remainder of the source
segment after n elements are taken.
scala> Segment.from(0).take(3).force.toVector res0: Vector[Long] = Vector(0, 1, 2) scala> Segment.from(0).take(3).drain.force.run.toOption.get.take(5).force.toVector res1: Vector[Long] = Vector(3, 4, 5, 6, 7) scala> Segment(1, 2, 3).take(5).drain.force.run res2: Either[(Unit, Long),Segment[Int,Unit]] = Left(((),2))
Returns a segment that outputs elements while p is true.
Returns a segment that outputs elements while p is true.
The result of the returned segment is either the result of the original stream, if the end
was reached and the predicate was still passing, or the remaining stream, if the predicate failed.
If takeFailure is true, the last element output is the first element which failed the predicate.
If takeFailure is false, the first element of the remainder is the first element which failed
the predicate.
scala> Segment.from(0).takeWhile(_ < 3).force.toVector res0: Vector[Long] = Vector(0, 1, 2) scala> Segment.from(0).takeWhile(_ < 3, takeFailure = true).force.toVector res1: Vector[Long] = Vector(0, 1, 2, 3) scala> Segment.from(0).takeWhile(_ < 3).drain.force.run.toOption.get.take(5).force.toVector res2: Vector[Long] = Vector(3, 4, 5, 6, 7)
Alias for map(_ => ()).
Alias for map(_ => ()).
scala> Segment(1, 2, 3).void.force.toList res0: List[Unit] = List((), (), ())
Returns a new segment which discards the result and replaces it with unit.
Returns a new segment which discards the result and replaces it with unit.
scala> Segment(1, 2, 3).take(2).voidResult res0: Segment[Int,Unit] = ((Chunk(1, 2, 3)).take(2)).mapResult(<f1>)
Returns a new segment which includes the number of elements output in the result.
Returns a new segment which includes the number of elements output in the result.
scala> Segment(1, 2, 3).withSize.drain.force.run res0: (Unit,Long) = ((),3)
Zips this segment with another segment using the supplied function to combine elements from this and that.
Zips this segment with another segment using the supplied function to combine elements from this and that. Terminates when either segment terminates.
scala> Segment(1,2,3).zipWith(Segment(4,5,6,7))(_+_).force.toList res0: List[Int] = List(5, 7, 9)
Potentially infinite, pure sequence of values of type
Oand a result of typeR.All methods on
Segmentsupport fusion with other arbitrary methods that returnSegments. This is similar to the staging approach described in Stream Fusion, to Completeness, but without code generation in staging.To force evaluation of one or more values of a segment, call
.forcefollowed by one of the operations on the returnedSegment.Forcetype. For example, to convert a segment to a vector, calls.force.toVector.Stack safety of fused operations is ensured by tracking a fusion depth. If the depth reaches the limit, the computation is trampolined using
cats.Eval.The
equalsandhashCodemethods are not defined forSegment.Implementation notes:
emits). As such, segments should update state before invoking callbacks so that remainders can be computed accurately.