Re: [cmucl-imp] Lexical environment and compiler macro functions.

15 Mar 2015

      On 15/03/2015, at 4:16 PM, Mark Cox wrote:
...
G'day,
CMUCL does not shadow the compiler macro function present in the
global environment when introducing a function with the same name in
the current lexical environment. This is demonstrated with the
following example:
(defun square (x)
    (expt x 2))
(define-compiler-macro square (&whole form arg)
    (declare (ignore arg))
    form)
(defun test ()
    (flet ((square (arg)
             (declare (ignore arg))
             (write "SQUARE!")))
      (macrolet ((my-square (arg &environment env)
                   (if (compiler-macro-function 'square env)
                       `(function square)
                       nil)))
        (my-square 1))))
(test)
  => #<Function (FLET SQUARE TEST) {48704B89}>
Forget this. I have miscomprehended the definition of MACROLET in the
Hyperspec.

  The macro-expansion functions defined by macrolet are defined in the
  lexical environment in which the macrolet form appears. Declarations
  and macrolet and symbol-macrolet definitions affect the local macro
  definitions in a macrolet, but the consequences are undefined if the
  local macro definitions reference any local variable or function
  bindings that are visible in that lexical environment.

Sorry.
Mark