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RE: Eval - Pro's and Con's (was Re: Dylan rather than CL -- why?)
- To: firstname.lastname@example.org
- Subject: RE: Eval - Pro's and Con's (was Re: Dylan rather than CL -- why?)
- From: Stuart Watt <S.N.K.Watt@open.ac.uk>
- Date: 8 Dec 92 14:31:44 U
JD writes (re: READ and PRINT)
>However, their usefulness is not confined to "command-line"
Well, I would say that read probably is only useful for this. read is
positively dangerous to deliver as it will make Lisp parsing so easy that my
favourite word processor will want me to enter styles in parentheses! print I
have no real problems with, although if read is not going to be delivered
printing will change as the read-print equivalence is not so important.
eval is a totally separate issue. Personally, I can't see much justification
for it, as apply is good enough for most purposes. An interpreter is an obvious
choice for an external (and very optional) module.
What I was trying to get at is that the traditional streamy Lisp IO is a
development environment thing, like MPW and the UNIX shell. Users want
something different, like "no" instead of #f. Similarly, on input, people don't
necessarily want "1/1" to be interpreted as a rational, they may just want to
use it as a name. Doing IO yourself (say using a custom parser) is the only
safe way, although print and read may be (and are!) great for development.