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(declare (type fixnum ---)) considered etc.
- To: DLW@QUABBIN.SCRC.Symbolics.COM, gls@Think.COM, common-lisp@SU-AI.ARPA
- Subject: (declare (type fixnum ---)) considered etc.
- From: Guy Steele <gls@Think.COM>
- Date: Thu, 24 Jul 86 09:53 EDT
- Cc: gls@AQUINAS
- In-reply-to: <860723145835.7.DLW@CHICOPEE.SCRC.Symbolics.COM>
Date: Wed, 23 Jul 86 14:58 EDT
From: Daniel L. Weinreb <DLW@QUABBIN.SCRC.Symbolics.COM>
Date: Wed, 23 Jul 86 12:32 EDT
From: Guy Steele <gls@Think.COM>
One thing one can say is (OR FIXNUM (SIGNED-BYTE 20)), say, which a
sufficiently clever compiler (heh, heh, heh) would understand to mean
"use a fixnum, unless fixnums are less than 20 bits, in which case use
at least 20 bits (whatever that takes)".
What is the advantage of using this instead of (SIGNED-BYTE 20)?
It feels more efficient.
Seriously, for declaring variables this probably buys you nothing.
I am guilty of somewhat fuzzy thinking. However, in the case of an
implementation that packs structs, using this type for a component
would make some sense. But I am reaching.