Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!decwrl!pa.dec.com!src.dec.com!hudson@yough.ucc.umass.edu
From: hudson@yough.ucc.umass.edu (Rick Hudson)
Newsgroups: comp.lang.modula3
Subject: Typefinger printing in SRC M3
Message-ID: <9102111538.AA24105@yough.ucc.umass.edu>
Date: 11 Feb 91 15:38:39 GMT
Reply-To: Hudson@cs.umass.edu
Lines: 17
In-Reply-To: saber.com!wyant@saber.COM's message of Mon, 4 Feb 91 09:36:37 EST <9102041436.AA28682@riposte>
To: saber.com!wyant@saber.com
Cc: m3


  My surface impression from scanning the sources is that works as
  follows. Each type (scalar or constructed) has an operation to return
  a textual type name. When fingerprinting a constructed type (esp. an
  object/record) a string is constructed containing the recursive
  enumeration of all scalar type names used in that constructed type.
  This string is then treated as input to the "poly" function to compute
  a 64-bit fingerprint.  
  Is this reasonably accurate or am I way out in left field >>


This was my impression of how SRC M3 works also. It is a reasonable
probabilistic approach to the problem. A non-probabilistic approach
would be to use the fingerprint only for determining if types were
*not* equivalent and actually compare structures before deciding
if they were equivalent.
- Rick