Path: utzoo!mnetor!uunet!ncc!alberta!att-ih!pacbell!ames!pasteur!cory.Berkeley.EDU!seitz
From: seitz@cory.Berkeley.EDU (Matthew Eric Seitz)
Newsgroups: comp.lang.modula2
Subject: Re: Structured Types
Message-ID: <2453@pasteur.Berkeley.Edu>
Date: 17 Apr 88 03:19:21 GMT
References: <5572@uwmcsd1.UUCP>
Sender: news@pasteur.Berkeley.Edu
Reply-To: seitz@cory.Berkeley.EDU.UUCP (Matthew Eric Seitz)
Organization: University of California, Berkeley
Lines: 31

In article <5572@uwmcsd1.UUCP> markh@csd4.milw.wisc.edu (Mark William Hopkins) writes:
>
"     Consider the following two segments:
"
"     A := 3;                A[1] := 3;
"     B := A;                B := A;
"     WriteCard(B)           WriteCard(B[1])
"
"They both do the same thing.  In the first, we can see that 3 will be
"written out by performing the successive transformations (beta reductions):
"
"A := 3; B := A; WriteCard(B) --> B := 3; WriteCard(B) --> WriteCard(3)
"
"However, were we to try this with the latter segment, we would be blocked.
"There is nothing that explicitly says that B[1] is assigned the value of
"A[1].
"[...]
"     There are two ways to go with this.  Either one could eliminate
"assignments to structured types -- essentially B := A is just a syntatic
"sugaring of the corresponding for loop -- or one could include structured
"EXPRESSIONS and CONSTANTS.
"[...]

	I don't see why you are blocked.  Modula-2 does implement your first
suggestion:  it is a sugaring of the corresponding for loop.  See _Programming_
In_Modula-2_ (3rd ed.) pp. 37, 1O5.  This does explicitly say that B[1] is 
assigned the value of A[1].  Also, this does not eliminate assignments to 
structured types.

						Matthew Seitz
						seitz@cory.berkeley.edu