Solved: thanks /u/dilap I was comparing the reflect.Value's, not the actual interfaces in reflect.DeepEqual().
I just see no reason it won't work:
It checks to make sure that the interface{} is a slice or array.
It ranges over the slice/array and if any element of the slice and the supplied value are deeply equal it returns true.
Otherwise, return false. (Array/Slice does not contain value).
This reflection stuff is hard 
评论：
dilap:
bkeroack:Here you go:
https://play.golang.org/p/kgAywwVMym
The problem is that DeepEqual wants the interface{}, not a reflect.Value. The reflect.Value themselves are not equal, but the values they represent are equal.
(As an aside, I would advocate not using reflection for something this. It will be slow, and defeats the type safety the language gives you. I would just write separate versions of contains for each type that you need. E.g., in this case, right conatins for []int. If you also need it for strings, then write containsInt and containsString. Sure, it's some copy-paste code duplication, but so what -- it's simple, fast, easy to understand code.)
Franke123:"[Reflection] is not for you" -- Rob Pike https://www.youtube.com/watch?v=PAAkCSZUG1c&t=15m29s
dilap:Ah, that makes sense! It was comparing the reflect.Value's, not the underlying interfaces. Thank you for the explanation!
As the response to the aside: I was just doing this for fun to learn about reflection, I usually just do a containsInt type thing for something like this. Thank you so much!
Happy to help!
