Re: History of lexical scope in Lisp

Paul Rubin <no.email@nospam.invalid> wrote:

Does anyone know when lexical scope started appearing in Lisp? Not
counting Scheme, did it exist in predecessors of Common Lisp? Was it
used much? Is it really true that Common Lisp had both lexical and
dynamic scope in order to support older code that was written relying
on dynamic scope and was too hard to convert?

  That question should be answered by someone from the standardizing
committee, but anyway I think that there's two questions here.

Dynamic scope is necessary for some things (e.g. mutable global
variables, the condition system, thread-local storage, etc.), and then
there is the general user-level facility for declaring special
variables. So it might very well be that the original motivations for
those are different...

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