yLockedTo specification

This is the engineering specification for the MotionObservable operator: yLockedTo.

Overview

yLockedTo sets the upstream point’s y value to the provided value and emits the result.

Example usage

stream.yLocked(to: 50)

upstream  yValue  |  downstream
20, 50    50      |  20, 50
40, 80    50      |  40, 50
60, 90    50      |  60, 50

MVP

Expose an yLockedTo operator API

Use _map to implement the operator. Accept an yValue number. Emit {upstream.x, yValue}.

class MotionObservable<number> {
  public func yLocked(to yValue: number) -> MotionObservable<Point>
}