xLockedTo specification

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

Overview

xLockedTo sets the upstream point’s x value to the provided value and emits the result.

Example usage

stream.xLocked(to: 50)

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

MVP

Expose an xLockedTo operator API

Use _map to implement the operator. Accept an xValue number. Emit {xValue, upstream.y}.

class MotionObservable<number> {
  public func xLocked(to xValue: number) -> MotionObservable<Point>
}