spec: negative value for slice index

[mattn]

hope equivalent to python's arr[1:-1]. for example:

arr := GetItems()
fmt.Println(arr[1:len(arr)-1])

we need to take arr as variable. but i want

part_of_arr := GetItems()[1:-1]

[adg]

The omission of this feature (present in Python, for example) is deliberate

When performing arithmetic on slice indices it would be unfortunate if an erroneous negative result "just worked" as a reverse index. This leads to subtle bugs.

There are readability benefits to the status quo, also. It is clear that the Go expression s[:i] is creating a slice of s that is i bytes long. If i could be negative then the reader would need more context to understand the slice expression.

This is in keeping with Go's general philosophy of avoiding subtle syntactic tricks.