From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Thorsten Jolitz <tjolitz@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: Adding assoc-delete-all / rassoc-delete-all
Date: Thu, 17 Apr 2014 09:15:03 -0400 [thread overview]
Message-ID: <jwvzjjkumwe.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <8738hcjfqo.fsf@gnu.org> (Tassilo Horn's message of "Thu, 17 Apr 2014 14:35:27 +0200")
> Strange that it compares with `eql'. Doesn't `eql' only allow comparing
> floating point values in addition to what's allowed by `eq'?
Common-Lisp simply uses `eql' by default "everywhere". That's because
the semantics of `eq' is pretty weird, really: if it weren't for `eq'
you could never tell the difference between two identical floats. So in
many ways, `eq' is a mistake which lets details of implementation
seep through.
Oh, and IIUC `eql' is also different from `eq' on all other immutable
objects (e.g. bignums).
> And floats don't seem to be reasonable candidates for a `case'
> distinction...
Indeed, but comparing their addresses is even less desirable.
Stefan
next prev parent reply other threads:[~2014-04-17 13:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-17 11:39 Adding assoc-delete-all / rassoc-delete-all Tassilo Horn
2014-04-17 11:55 ` Thorsten Jolitz
2014-04-17 12:29 ` Stefan Monnier
2014-04-17 13:36 ` Thorsten Jolitz
2014-04-17 12:35 ` Tassilo Horn
2014-04-17 13:15 ` Stefan Monnier [this message]
2014-04-17 13:40 ` Thorsten Jolitz
2014-04-17 15:17 ` Teemu Likonen
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