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Re: sweet-expressions are not homoiconic

This page is part of the web mail archives of SRFI 110 from before July 7th, 2015. The new archives for SRFI 110 contain all messages, not just those from before July 7th, 2015.

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        John Cowan writes:

 > John David Stone scripsit:
 > > From the beginning, there was an obvious impediment to the use of
 > > sweet-expressions:  Readers who are accustomed to alphabetic writing
 > > systems in which whitespace is almost invariably used as a word
 > > separator, a paragraph separator, a decorative typographical element,
 > > or for page layout simply don't respond psychologically to whitespace
 > > characters as they do to visible characters such as parentheses.
 > Ifthatwerereallytruewedstillallbewritinginscriptiocontin
 > ualikethiswherelinesarebrokenanywhereatall.

        Well, it did take a considerable time (measured in generations) for
the use of whitespace as a word separator to become standard.  But there
was an obvious motivating advantage in that case: separated-word texts are
significantly less ambiguous.  No such advantage accrues to

 > > Whitespace characters don't look like grouping symbols, as
 > > parentheses, brackets, braces, or oriented quotation marks do, because
 > > they don't have appropriate shapes and don't come in pairs.  Moreover,
 > > they don't visibly nest, so it is unnatural to use them to represent
 > > recursively defined syntactic structures.
 > Au contraire.  It is so natural than even suits use nested indentation
 > to show hierarchy in their PowerPoints.

        Yes, and we see how well that works out when the hierarchies are as
deeply nested as those in LISP-like languages are.

        The other common case of the use of indentation to indicate
grouping is legislative bills, which I would hesitate to cite as exemplars
of readability and homoiconicity.

        It's not a persuasive argument to say that Scheme programs could be
made just as readable as Congressional legislation and the wordier kinds of
PowerPoint slides.

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