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From: art@maui.Berkeley.EDU (Arthur Goldberg)
Newsgroups: comp.lang.misc,comp.lang.pascal
Subject: Re: Threatening Pascal Loops
Message-ID: <11503@shemp.CS.UCLA.EDU>
Date: 21 Apr 88 23:17:20 GMT
References: <793@virginia.acc.virginia.edu> <2827@enea.se> <1557@pasteur.Berkeley.Edu> <2773@mmintl.UUCP> <294@tmsoft.UUCP> <11047@shemp.CS.UCLA.EDU> <3364@omepd> <11369@shemp.CS.UCLA.EDU>
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A language developed i  at IBM research called Hermes (formerly NIL)
addresses these issues with the concept of "typestate".   The basic
idea is that at COMPILE-TIME the current state of each variable is
known at each line in the p  code.  For example,a pointer may be NIL,
pointing to an uninitialized data item, or pointing to an initialized item.
The operations allowed on a variable depend on its type state. Only
initizlized variables can be found on the right hand side of assignments,
or sendt in messages, for example.  See Strom et . al . publications
from IBM research.

Pardon the appearance.   Im using an unidentified editor.

Arthur Goldberg
UCLA computer Science Department
art@cs.ucla.edu