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From: neff@Shasta.STANFORD.EDU (Randy Neff)
Newsgroups: comp.lang.ada
Subject: Re: Typing Ada
Keywords: graphical design
Message-ID: <2831@Shasta.STANFORD.EDU>
Date: 25 May 88 16:57:52 GMT
References: <12400764147.13.RCONN@SIMTEL20> <25135.580491166@mbunix> <1017@cresswell.quintus.UUCP>
Reply-To: neff@Shasta.UUCP (Randall Neff)
Distribution: na
Organization: Stanford University
List-Id: <comp.lang.ada>

I would like to point out that very complex functional objects are designed
primarily with graphics, namely integrated circuits.   This is done through
a series of different abstractions and hierarchy.   
Abstractions:	Functional blocks
		Logic gates
		Transistors
		Mask rectangles
Hierarchy:	Cells of cells of cells of mask rectangles

In Ada, there is only a single hierarchy mechanism, the package; and only
a single abstraction, the programming language code.

Our research at Stanford with the language Anna (ANNotataged Ada) is 
adding an additional abstraction layer, an implementation independent
functional specification of a package specification.   This is equivalent
to a logic diagram of an IC;  the logic diagram explains how the chip
behaves, but not exactly how it is implemented in transistors or mask 
rectangles.