Is dispatch! an OK alternative to alt + cut_err?

[adamchalmers]

Winnow tutorial chapter 6 suggests using cut_err in an alt if you know that each branch has a unique prefix and therefore shouldn't backtrack.

But isn't this also the use-case for dispatch! -- so you should consider using dispatch! in this specific case?

If so, maybe the chapter 6 tutorial should suggest this.

[epage]

In that exact case, yes, dispatch will get the job done and this is covered in an earlier chapter. The point here is more to illustrate the concept of cut_err. There are times when you can't convert a alt + cut_err into a dispatch.

I would be interested in better understanding your thought process that led to this to better understand how much of a problem it is. I'm liking keeping the examples building on each other and I dislike having a lot of side notes for exception cases, so I'd lean towards keeping it as-is but someting led you to creating this.

[adamchalmers]

It's definitely not a problem, and once I properly understood cut_err it became clear to me that these two should be equivalent. I was mostly filing this to get your feedback on whether I should add a little note in that doc saying "in this specific case, you could use dispatch! to achieve the same effect, because dispatch will not try other branches".

(I guess I like when docs link back to other related concepts but maybe you'd like to avoid little notes like that in order to keep the page tightly-focused on just cut_err)