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From: gvcormack@watdaisy.UUCP (Gordon V. Cormack)
Newsgroups: net.micro,net.lang
Subject: Re: PL/I unspec (re: Ada unchecked conversion)
Message-ID: <7325@watdaisy.UUCP>
Date: Fri, 21-Jun-85 17:54:26 EDT
Article-I.D.: watdaisy.7325
Posted: Fri Jun 21 17:54:26 1985
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References: <1649@reed.UUCP> <186@harvard.ARPA> <453@calmasd.UUCP> <192@harvard.ARPA> <266@sdcc13.UUCP> <197@harvard.ARPA> <2323@sun.uucp>
Organization: U of Waterloo, Ontario
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> "unspec" (which, like PL/I's pointers, was typeless); Mesa has a bit-for-bit
> type conversion operator "loophole" similar in concept to Ada's.
> 	Guy Harris

PL/I's "unspec" is not typeless; it is a unary function that returns
a bit string that is the internal representation of its operand.
Unspec can also be used as the target of an assignment statement.
In this situation, the value assigned must, again, be a bit string.
The bit string replaces the internal representation of the operand.
-- 
Gordon V. Cormack      CS Department, University of Waterloo
   gvcormack@watdaisy.uucp     gvcormack%watdaisy@waterloo.csnet