[plt-scheme] match-lambda and source location

match-lambda creates a lambda without overriding syntax information. 
This greatly reduces the information content in stack traces.

OTOH overriding the source information for the lambda keyword greatly 
reduces the clarity of the macro code...

An idea: (WARNING: may be stupid ;)
Maybe the stack trace should not trace the real stack at all? It could 
get new marks every time the source location barier is crossed (so the 
lambda is reported as a part of match-lambda macro definition source but 
the expression in its body is also mentioned). It could also track tail 
calls in a length limited list (forgetting older "stack" frames).

-- 
regards,
Jakub Piotr Cłapa