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Diffstat (limited to 'core/src/mill/util/EitherOps.scala')
-rw-r--r-- | core/src/mill/util/EitherOps.scala | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/core/src/mill/util/EitherOps.scala b/core/src/mill/util/EitherOps.scala new file mode 100644 index 00000000..da2552c8 --- /dev/null +++ b/core/src/mill/util/EitherOps.scala @@ -0,0 +1,18 @@ +package mill.util + +import scala.collection.generic.CanBuildFrom +import scala.collection.mutable +import scala.language.higherKinds + +object EitherOps { + + // implementation similar to scala.concurrent.Future#sequence + def sequence[A, B, M[X] <: TraversableOnce[X]](in: M[Either[A, B]])( + implicit cbf: CanBuildFrom[M[Either[A, B]], B, M[B]]): Either[A, M[B]] = { + in.foldLeft[Either[A, mutable.Builder[B, M[B]]]](Right(cbf(in))) { + case (acc, el) => + for (a <- acc; e <- el) yield a += e + } + .map(_.result()) + } +} |