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by kragen 1718 days ago
Whether a Lisp is a Lisp-1 or a Lisp-2 is orthogonal to whether its scoping is lexical or dynamic. There are lexically-scoped Lisp-1s (like Scheme), lexically-scoped Lisp-2s (like Common Lisp), and dynamically-scoped Lisp-2s (like Emacs Lisp). Someone's probably written a dynamically-scoped Lisp-1 at some point, but I can't think of one.
1 comments
_0ffh 1718 days ago
Does Russell's original Lisp count as a Lisp-1? I guess it probably had a common namespace for functions and values.
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kragen 1718 days ago
It's an interesting question; maybe he remembers. If it was a Lisp-1 when originally implemented, it became a Lisp-2 within the first year or two, using different properties of atoms (symbols, as we say now) to evaluate them in "function position" than when they weren't. I suspect he might have made that change before he got it working at all because of properties like FSUBR and FEXPR.

It was definitely dynamically scoped, though.

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