Subject: Re: Q: 101 Buzzwords in Scheme
From: Erik Naggum <>
Date: 1998/01/02
Newsgroups: comp.lang.scheme,comp.lang.lisp
Message-ID: <>

* Brian Harvey <bh@anarres.CS.Berkeley.EDU>
| First of all, it's unfortunate that there are notations '# and #' whose
| meanings are unrelated.

is '# a notation?  for what?

# is a dispatching macro character in Common Lisp -- it takes another
character to become a reader macro function.  Scheme has this implicitly,
too, in the vector syntax: #(...).

but this is like saying that since #(:foo) is a vector of one keyword and
(#:foo) is a list of an uninterned symbol, something is "unfortunate" in
the syntax.  I don't buy this (rather silly) argument at all.

| And in the case of #' the meaning has nothing to do with quotation.

#(...) has nothing to do with lists, either.  #:... has nothing to do with
keywords, #+... has nothing to do with the plus operator, etc, for all #x
and x.  what's the big problem?

on other hand, (mapcar #'foo ...) replaced (mapcar 'foo ...) and in many
cases, #'(lambda ...) replaced '(lambda ...), so it is not as unrelated as
you seem to want it to be,

| More deeply, I find it confusing that the meaning of (function foo)
| has very little to do with the meaning of (function (lambda ...)).
| The first is a selector, extracting an existing piece of information
| from a data structure; the second is a constructor, creating a closure.

it's amusing to see how mistaken you are when you criticize Common Lisp,
almost to the point of being ridiculous.  I wanted to comment on this
previously, too, but it's not very constructive, however, when it goes on
and on unchecked, you do need correction.

the accessor you allude to is `symbol-function'.  it only works on symbols,
but `function' works on function names, which also exist in the lexical
environment, where they aren't symbols any more than lexical variables are.

| But then, I don't like the way SETF blurs the distinction between list
| mutation and variable rebinding, either.  My students have enough trouble
| keeping it straight when they are restricted to distinct SET!  and
| SET-CAR! notations.  This is the same sort of issue, I think.

"list mutation"!?  `setf' is a lot more than that.  indeed, from the
history of the name that I obtained this newsgroup (I believe that, too,
was Kent Pitman giving a lecture :), it's from "set field", and referred
initially to fields in structures, but grew into a more general mechanism.

I don't see the problem with this, either.  (setf variable value) is very
obviously very different from (setf (car variable) value) and it would take
a serious amount of _misunderstanding_ to confuse the two.

however, (setf symbol value) is like (setf (symbol-value 'symbol) value),
which is also a mutator of a slot in a data structure, this time a symbol.
(this is also the old (set 'symbol value) in a new wrapping.)

personally, I think Scheme's lack setf and its insistence of a pre-setf
mode of writing mutators is really _ugly_.

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