dictionary - why slice values can sometimes go stale but never map values?

Question

I find that slice map function and channel are frequently mentioned together as reference types. However I notice that slices somethings exhibit none reference behavior like they can go stale:

   var s []int
   //must update slice value
   s = append(s, ...) 

or

   //must use pointer if we want to expose the change
   func foo(s *[]int) error  
   //or change the function signature to return it like _append_
   func foo(s []int) (r slice, err error)

Usually I understand this by keeping the inner components of the slice discriptor implementation in mind: A slice value can be seen as a struct of len, cap and data pointer.

But map values need never bother like

   m := make(map[string]int)
   ...
   // don't know how to express with insertion, but you know what i mean.
   m = delete(m, "well")  

Why? Is a map value just a pointer to the map descriptor? If so why not also make slice this way?

Answer 1

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