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Declarations and Ignorance
- To: common-lisp at SU-AI
- Subject: Declarations and Ignorance
- From: Dick Gabriel <RPG at SU-AI>
- Date: Mon, 20 Sep 1982 14:39:00 -0000
There should NOT be a way to ask the type of a variable!
CL is not a typed-variable language. Implementations
are EXPLCITLY ALLOWED to ignore all type declarations.
This statement seems hastily spoken: if CL has as a goal guaranteeing that
compiled-code semantics are the same as interpretted-code semantics, and
if stock hardware is allowed declarations for the compiler, then it seems
that the interpreter has to be able to obtain the type of a variable.
That is, unless CL is one of those languages whose machine is allowed to
consult an oracle on certain questions.
If you want to EXPLICITLY ALLOW an implementation to IGNORE *ALL* type
declarations, then the way that asks of a variable, what type are you?, can
simply be the constant function #'(LAMBDA (X) 'POINTER).