Re: Issue: ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS (Version 9)

[Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>]

Also, for any given application, you usually know what types you care
about, so you can write a special-purpose, non-consing version for
that purpose by pre-caching the results at load time. For trivial
extra cost, you can have a table incrementally updated only on the
first call to the portable function with a particular argument, so the
end effect is negligible consing even in the general case.