wanted: dx (LET ((F (LAMBDA ...))) ...)

[Nikodemus Siivola]

Currently

  (LET ((F (LAMBDA ...)))
    (DECLARE (DYNAMIC-EXTENT F))
    ...)

will not stack allocate the closure, which not only stands in the way of idiomatic and efficient code, but makes it harder to ensure that a source transform/macro-expansion will produce efficient code. If the above worked, non-captured functional arguments could be just bound as above by quantifier/iterator transforms -- if we had ones that cared about DX.