(It seems that I sent this to wrong address, so this is a retry)

However, existing implementations must already have internal type 

handling mechanisms, and if an implementation already supports some

record type, it's likely that it wants to directly integrate it to the internal

type system.  Such internal type system doesn't need to fit smoothly

with srfi-137 protocol, in which case srfi-137 just adds complexity as

opposed to simplifying it.