No, because if the function that includes those lines is itself async, it will now block, while the equivalent go coroutine will still preserve the stackfull-asyncness. I.e. you can't close over the yield continuation in rust, while it is implicitly done in go.
For a more concrete example: let's say you have a generic function that traverses a tree. You want to compare the leaves of two trees without flattening them, by traversing them concurrently with a coroutine [1]. AFAIK in rust you currently need two versions of traverse, one sync one async as you can't neither close over nor abstract over async. In go, where you have stackful coroutines, this works fine, even when closing over Context.
So yes, in some way Context is a color, but it is a first class value, so you can copy it, close over it and abstract over it, while async-ness (i.e. stackless coroutines) are typically second class in most languages and do not easily mesh with the rest of the language.
[1] this is known as the "same fringe problem" and it is the canonical example of turning internal iterators into external ones.
For a more concrete example: let's say you have a generic function that traverses a tree. You want to compare the leaves of two trees without flattening them, by traversing them concurrently with a coroutine [1]. AFAIK in rust you currently need two versions of traverse, one sync one async as you can't neither close over nor abstract over async. In go, where you have stackful coroutines, this works fine, even when closing over Context.
So yes, in some way Context is a color, but it is a first class value, so you can copy it, close over it and abstract over it, while async-ness (i.e. stackless coroutines) are typically second class in most languages and do not easily mesh with the rest of the language.
[1] this is known as the "same fringe problem" and it is the canonical example of turning internal iterators into external ones.