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From: jlg@lanl.ARPA
Newsgroups: net.lang
Subject: Re: Pascal typing
Message-ID: <20081@lanl.ARPA>
Date: Wed, 23-Jan-85 13:13:49 EST
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Posted: Wed Jan 23 13:13:49 1985
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> Can you give examples of things Pascal prevents you from doing, type-wise
> (leave out decent i/o, casts and type conversions, stuff like that - we all
> know that these are silly omissions from the language, and they ARE in
> Modula-2)?


Seperate compilation is restricted by Pascal since all proceedures used
must be declared (and therefore present in their entirity) within the
compilation unit that uses them.  This restriction was explicitly for the
purposes of strong typing (I believe they even discuss this in the Pascal
'User Manual and Report').  Ada corrects this problem by requiring only the
specification of a proceedure to be present in the proceedure that uses it.

In Pascal all actual array parameters must have the same size as the formal
array parameter was declared in the proceedure.  This means that general
purpose matrix handlers, FFT's, etc. can't be written in pascal (or you
must have a seperate copy for each size of array you wish to use in the
present code).  ISO Pascal and Ada both have ways around this problem.

Pascal doesn't allow overloading of function names (not necessarily a
disadvantage).  Ada allows this to an unfortunate extreme (redefining
operators such as '+' and '*' is a capability which causes no end to
maintenance problems).

There are other problems with Pascal typing, but this will already be
enough to start lots of net arguments.

J. Giles