Error Signalling

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

    Date: Thu, 26 Jun 1986  23:14 EDT
    From: "Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>

    The question we should address is what we should say about such errors
    in the standard for Common Lisp.  There are three options:

    1. The status quo: each of these things "is an error", but it is
    entirely up to the implementor whether and under what circumstances to
    detect and signal these errors.

    2. The rigorous solution: For errors of the types described above, it is
    REQUIRED that implementations signal an error in interpreted code.  It
    is also required that these errors be signalled in compiled code unless
    (optimize (safety 0)) is in effect at compile time.

    3. Sitting on the fence: The conditions stated in option 2 are not
    required in the spec, but they are "recommended".

#2 has always been the policy in Symbolics' implementation.  That's
an implementation design decision.  I don't feel qualified to judge
whether #2 should be the language specification, or whether it's
better for the language to permit laxer implementations.