Vectors versus Arrays

[MOON at SCRC-TENEX]

I think the point here, which perhaps you don't agree with, is that
"vector" is not a useful concept to a user (why is a vector different from
a 1-dimensional array?)  It's only a useful concept to the implementor, who
thinks "vector = load the Lisp pointer into a base register and index off
of it", but "array = go call an interpretive subroutine to chase indirect
pointers", or the code-bummer, who thinks "vector = fast", "array = slow".
Removing the vector/array distinction from the guts of the language is in
much the same spirit as making the default arithmetic operators generic
across all types of numbers.

I don't think anyone from "the Symbolics crowd convinced us that changing
things were too hard for them"; our point was always that we thought it was
silly to put into a language designed in 1980 a feature that was only there
to save a few lines of code in the compiler for the VAX (and the S1), when
the language already requires declarations to achieve efficiency on those
machines.

If you have a reasonable rebuttal to this argument, I at least will listen.
It is important not to return to "four implementations going in four different
directions."