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Re: FIXNUM considered useful
- To: common-lisp@su-ai.ARPA
- Subject: Re: FIXNUM considered useful
- From: Masinter.pa@Xerox.COM
- Date: Fri, 25 Jul 1986 16:51:00 -0000
- In-reply-to: "Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>'s message of Fri, 25 Jul 86 11:36 EDT
Its possible to be more explicit about the implementation dependent
range of fixnums without resorting to red ink.
In explicit terms of CLtL, I'd propose the following changes in wording:
On pp 14-15, move the paragraph "In every Common Lisp implementation
to the end of the section on "Integer" (rather than the middle) and
put it in an Implementation Note rather than in the running text.
Change "In every Common Lisp implementation..." to "In most Common Lisp
implementations ..." and change "... is visible to the user in only a
few places where the efficiency of representation is important." to "...
is usually only visible to the user in cases where fixnum operations are
substantially more efficient than those that admit bignums." The
"efficiency of representation" is bogus: (signed-byte 8) is more
efficient in representation than fixnum. Fixnum declarations are not for
efficiency of representation but rather for efficiency of operations
such as + and *.
Add, after the sentence "Exactly which integers are fixnum is
implementation-dependent ..." a sentence: "For this reason, references
to the distinction between fixnum and bignum should be avoided in
portable code when more explicit integer ranges can be supplied." Add,
to the list of tokens to "See" the names "integer", "signed-byte".