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Re: Pushing the `gnus-range-*' functions down into the C layer

From: Stephen J. Turnbull
Subject: Re: Pushing the `gnus-range-*' functions down into the C layer
Date: Sun, 12 Sep 2010 00:36:16 +0900

Lars Magne Ingebrigtsen writes:
 > Stefan Monnier <address@hidden> writes:
 > >> Well, that's the case in Common Lisp, but it needn't be in Emacs
 > >> Lisp.  `eq' could just use `=' as the comparison function for
 > >> bignums.  Even though that would be a non-traditional way of
 > >> doing it.
 > >
 > > You're basically suggesting to replace `eq' with `eql', which has
 > > non-trivial performance implications.
 > Well, only for the new bignum type.

No, for all types.  First you have to check whether something is a
bignum, then if not you do a bit-pattern comparison.  Worst case this
could double the cost of doing EQ(x,y) in C, and in Lisp `eq' will
cost a perceptible amount more.

FWIW nobody has complained that for bignums (= x y) doesn't imply (eq
x y) in XEmacs.  You might want to ask the SXEmacs people what their
experience is.

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