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From: ted@nmsu.CSNET
Newsgroups: mod.ai
Subject: turbo prolog
Message-ID: <8606260655.AA27553@ucbvax.Berkeley.EDU>
Date: Sun, 22-Jun-86 14:54:16 EDT
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Posted: Sun Jun 22 14:54:16 1986
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Recent reviews have correctly pointed out that turbo prolog's
attempt to enforce type checking has both good and bad points and
that the speed is not very impressive, since much of the
unification can be done at compile time if data types are known.

The major difficulty with Borland's approach to adding strong
typing to prolog is the loss of higher-order predicates.  Since a
domain can be at most the disjunction of a small number of
_predeclared_ terms, it is impossible to write a general higher-
order procedure.

This means that you can't write findall, as described in Clocksin
and Mellish (Borland has of course, in their wisdom, provided
such a function).  The function doall also cannot be written.  It
is handy as a substitute for findall when the predicate Q is
executed for effect only.

	doall(Q) :- Q,fail.
	doall(_).

First class procedural objects are, in many senses, a much more
fundamental distinction between symbolic and conventional
languages than are heap allocated data structures.  Their loss
makes many advanced applications nearly impossible.