``Update functions'' in Scheme.

[Stephen Robbins <Stever@WAIKATO.S4CC.Symbolics.COM>]

    Date: Mon, 9 May 88 23:02:20 ast
    From: Bard Bloom <bard@THEORY.LCS.MIT.EDU>

    I'm not exactly sure what a language extension is.  I am pretty sure that
    SETF in Lisp is a macro.

Yep [see my previous message].

       (SETF (UNKNOWN-SETTER v) y) expands to something like Lyn's or T's method,
    where the setter is looked up dynamically.

This will give a compiletime error that no SETF method is known for
UNKNOWN-SETTER.

- Stephen