分配等效类型的切片不起作用

Question

Why doesn't this work?

package main

type Word uint8
type Memory []Word

func main() {
    bytes := []uint8{}
    memory := Memory{}
    bytes = memory
}

The compiler generates this error:

9:9: cannot use memory (type Memory) as type []byte in assignment

As I understand it, []uint8 and Memory should be mutually assignable.

Answer 1

Here are the assignability rules

In this particular case none of those is held, so the types are not assignable.

Given you mentioned this answer is not detailed enough - let's run through every assignability rule: (for ease let's use A as a substitute for []uint8 and B as a substitute for []Word)

• x's type is identical to T. --- Nope, A is not identical to B
• x's type V and T have identical underlying types and at least one of V or T is not a defined type. --- Nope, both are defined types
• T is an interface type and x implements T. --- None of them is an interface
• x is a bidirectional channel value, T is a channel type, x's type V and T have identical element types, and at least one of V or T is not a defined type. --- None of them is a channel
• x is the predeclared identifier nil and T is a pointer, function, slice, map, channel, or interface type. --- None of them holds nil value
• x is an untyped constant representable by a value of type T. --- Nope, no constants involved

So, as you can see - there is no way A is assignable to B.

If you declare Memory as type Memory []uint8 it would work (as @RayfenWindspear mentioned in the comments), I'm sure though the question roots is more "why" not "how to fix".