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Redefinition of CL Functions
- To: Jim Kempf <kempf%hplabsc@HPLABS.HP.COM>
- Subject: Redefinition of CL Functions
- From: Rob MacLachlan <RAM@C.CS.CMU.EDU>
- Date: Tue, 14 Apr 1987 16:13:00 -0000
- Cc: common-lisp@SAIL.STANFORD.EDU, ROSENKING@A.ISI.EDU
- In-reply-to: Msg of 14 Apr 1987 11:44-EDT from Jim Kempf <kempf%hplabsc at hplabs.HP.COM>
One point that should be introduced into this discussion is the
distinction between "legal" and "reasonable". It is not feasible for
Common Lisp to mandate reasonableness; users will have to decide for
themselves whether a given implementation is reasonable. With any
standard it is possible to create a system that complies with the
letter of the standard, but is still totally unusable.
In the case of redefinitions of standard functions and macros I would
say that reasonable implementations should both:
-- Warn when the user redefines a standard function or macro and
-- Do its best to make the user redefinition work.
I don't think either property can be brought within the formal
language definition, so an implementation that flames out and dies
when you redefine a standard function would be legal.