[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

questions about IF

    Date: Fri, 10 Jun 88 14:03:06 EST
    From: bouma@purdue.edu

    I just noticed something strange about the Symbolic's IF:
    So the else-clause to an IF is an implicit PROGN.
    This is NOT in the Common-Lisp language specification?

This is a documented feature of Symbolics' CL implementation.
Personally I think they should keep scl extensions (like LOOP keywords,
IF, and defun with a non-symbol as its name) out of CL, but I can
understand why that's hard to do.

    Personally I believe it is an error since the code looks so funny :^)

Personally I prefer it, but if you don't like it write your own if macro
(but be sure to shadow lisp:if when you build your package).

	 Someone said recently in this group that IF is now a more primitive than
    the COND. Can I get more details on this? How could they have done this? Does
    my code run faster now if I use Ifs than if I use Conds?

I was surprised to hear Moon say this, because it seems like a red
herring.  What does "more primitive" imply in an environment with
macros?  Who cares whether a expands into B or vice versa?