[Types-sig] the very last thing

[Samuele Pedroni]

Here's a concrete example why it makes sense to distinguish
the various kinds of checking: once you have interfaces
it is typical (so it is in java  AFAIK) to use very inexpressive names
for the methods, something along the way of:

interface ObjectDocReader:
  def read()
  
  
a typechecking that in this case is just happy about finding a 'read'
method will be easely defeated and your program will deliver you
the old weird errors. Better to ask people to put an implements 
assertion in their new code, in this case.

regards.