This issue was originally filed by @tatumizer

Currently, to add annotation to function, we have to use a named function.
The issue comes into play especially while passing a function as parameter, or defining array of functions, or including a function as a value in a map literal.
Probably not a big deal, but supporting annotations for function literals directly will make things more uniform; the feature doesn't seem to interfere with anything else, so adding it won't cause collateral damage.