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- To: Common-Lisp@SU-AI.ARPA
- Subject: Void
- From: Rob MacLachlan <RAM@C.CS.CMU.EDU>
- Date: Tue, 13 May 1986 00:00:00 -0000
- In-reply-to: Msg of 12 May 1986 06:28-EDT from Kent M Pitman <KMP at SCRC-STONY-BROOK.ARPA>
Let be rephrase the VOID proposal in terms of continuations,
hopefully making the semantics seem less arbitrary:
1] THE and the result type for a function type are statements about
the type of continuations with which it is legal to call a
function or evaluate an expression.
2] VALUES and the proposed VOID are only meaningful in this context
because they can only apply to continuations, not the values of
3] Stating that a continuation must be VOID is stating that the
continuation cannot reference its arguments *in any way*.
Excepting the funny cases of MULTIPLE-VALUE-PROG1 and UNWIND-PROTECT,
these statements are comparable to the previous definition, but a bit
stronger. The cases where I said that VOID should be erroneous are
those cases where it is obvious that the continuation for the
expression is not VOID.