Re: question about Quasiquote

[William Clinger <will@skinner.cs.uoregon.edu>]

Matthias Blume writes concerning QUASIQUOTE:

    I don't like the current definition of quasiquote's semantics.  I
    think it is not general enough and I cannot see any use of the (very
    complicated) nesting level business.

Below is an example of nested QUASIQUOTE from a system for hygienic
macro expansion.  The need for nested QUASIQUOTE does not arise from
EVAL, but rather from UNQUOTE and UNQUOTE-SPLICING.

(define (expand-letrec bindings body)
  `((,new-lambda ,(map car bindings)
                 ,@(map (lambda (binding)
                          `(,new-set! ,(car binding)
                                      ,(cadr binding)))
                        bindings)
                   ,@body)
    ,@(map (lambda (binding) `(,new-quote unspecified)) bindings)))

William Clinger