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- To: masinter at PARC-MAXC
- From: Kent M. Pitman <KMP at MIT-MC>
- Date: Mon, 13 Sep 1982 23:31:00 -0000
- Cc: Common-Lisp at SU-AI
It makes a difference whether coercion is to upper or lower case.
Programs have to know which to expect. Changing the direction will break
programs. eg, all FASL files would have to be recompiled because READ
would not get called to hack the case of the symbols dumped out in them, etc.
I think the right answer is that the bulk of the existing systems
already coerce to upper case and have programs relying on that fact.
That being the case, I think it contrary to the principles of Common
Lisp to ask that this be changed. It is an arbitrary decision and will
not affect program transportability, expressive power, or whatever.
The switch proposed to allow downcasing on output should satisfy the
needs of those who like lowercase output, but its essential to the
correctness of such a switch that all implementations coerce in the same
direction and i think that uppercase is the right direction to minimize
the greatest amount of hassle.
If this were a new Lisp being designed from scratch, one might argue
legitimately that lowercase should be the case of choice internally. I
certainly wouldn't, but people might.... but since it's a language spec
designed to make existing code more runnable, not less so, I think maintaining
the status quo as much as possible on such issues is the right thing.