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From: chip@soi.UUCP (Chip Morris)
Newsgroups: comp.lang.scheme
Subject: Re: Why memq vs memv vs member, etc.?
Message-ID: <chip.674143084@soi>
Date: 13 May 91 13:58:04 GMT
References: <1991May10.230057.15591@Think.COM>
Organization: Software Options Inc.,  Cambridge,  Mass.
Lines: 22

barmar@think.com (Barry Margolin) writes:

>....  This seems to be an area where Common Lisp does what
>I'd expect Scheme to do; CL has a single MEMBER function with a :TEST
>option, while Scheme has MEMQ, MEMV, and MEMBER.  Why not (member <obj>
><list> eq?) instead of (memq <obj> <list>)?  

I agree with Mr. Margolin on the style and generality of his proposal.
However, I just finished speeding up a large Common Lisp application
in which using MEMQ was much faster than using MEMBER
(with a :TEST of #'EQ) was quite significant.  The overhead of the
additional parameters, especially keyword parameters, was alone enough
to make a difference.  

Interestingly, the MEMQ provided as an extension by the implementation
(Lucid) ran at about the same speed as a naively programmed MEMQ.  So
the presence of a good compiler suggests keeping language constructs
to a minimum, more a Scheme idea than a Common Lisp idea.
-- 
Chip Morris, Senior Engineer
Software Options, Inc., 22 Hilliard St., Cambridge MA 02138  (617) 497-5054
chip@soi.com