[API]Why are there so many APIs which have a WithPatches suffix

[lightsprint09]

Why are there so many APIs which have a WithPatches suffix. Would it for example not enough to have one merge which returns [Patche] by default. Has this some performance reasons?

Example:

@discardableResult
 public func merge(other: Document) throws -> [Patch] {

[alexjg]

Generating patches changes the way that automerge processes operations, for example if we're generating patches then when a key is deleted we need to figure out if the deletion of the operation in question exposes any concurrent values which were hidden by the deleted key and then we have to generate patches which represent the creation of the exposed value. The performance impact can be large enough on large document histories that I don't think we should deny the user the option to choose whether to generate patches.