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Re: Backquote idioms
- To: common-lisp@su-ai.ARPA
- Subject: Re: Backquote idioms
- From: Steven M. Haflich <smh@mit-eddie.ARPA>
- Date: Wed, 22 May 85 14:33:01 edt
From @SU-AI.ARPA:DCP@SCRC-STONY-BROOK.ARPA Wed May 22 12:01:25 1985
Subject: Backquote idioms
Do you all believe these?
Does it matter? RWK said he has never used a triple backquote.
Neither have I. There may be applications which are really good
hacks, but can they be maintained? Even some double nested backquotes
require enough though[t] that they should probably be avoided.
Conciseness and compactness does not imply clarity and robustness.
I plead that it *does* matter. It does not depend on the wisdom of
anyone (other than my good friend Bernie) writing triple nested
backquotes. Consider rather automatic code generators. Sometimes a
code generator needs output source code to a file, instead of
generating forms in memory. Backquotes exist not to provide any
additional expressiveness in printed representations, but (roughly) to
make clearer constructions which embed the results of form evaluation
inside a template. It is conceivable that a good automatic code
generator could use backquotes to aid human readablility of its
output, if only to aid debugging. But an automatic code generator
might, like Bernie, lack sufficient discretion not to nest backquotes
in cases where readability is indeed *not* enhanced.
I apologise to BSG for pulling his leg a little, but the point is
serious: CLTL must either document firmly that more than two levels
of backquotes are undefined, or else the reader grammar must be clear
and obeyed by all implementations.