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defmacro within defmacro
Date: Wed, 23 May 90 18:47 PDT
From: Charest@AI-SUN.jpl.nasa.gov (Len Charest)
I want to define a macro that defines another macro with some complex template that is best
explained by example. Here goes...
The macro I am actually writing (let's call it MACRO-MAKER) should have the following syntax:
(macro-maker name arglist)
An example of its use looks like:
(macro-maker foo (bar baz ad infinitum))
=> FOO
The contract of macro-maker is to define a macro with the given name and arglist. The example above
defines a macro named FOO that takes 4 required arguments.
(foo 1 2 3 4)
=> ...some result...
If I say:
1 (defmacro macro-maker (name arglist) ;name and will become part of the inner macro's template
`(defmacro ,name ,arglist
0 ;;the function some-function takes multiple literal patterns (ie. lists) as its arguments
;;assume the lists are self-quoting
1 `(some-function ,,@(loop for arg in arglist
0 1collect `(0literal1 ,arg)))))
0 => MACRO-MAKER
I get:
(macroexpand-1 '(macro-maker foo (bar baz ad infinitum)))
=> (DEFMACRO FOO (BAR BAZ AD INFINITUM)
`(SOME-FUNCTION ,(LITERAL BAR)
,(LITERAL BAZ)
,(LITERAL AD)
,(LITERAL INFINITUM)))
T
What I want is to define MACRO-MAKER so that its expansion looks EXACTLY like:
(DEFMACRO FOO (BAR BAZ AD INFINITUM)
`(SOME-FUNCTION (LITERAL ,BAR)
(LITERAL ,BAZ)
(LITERAL ,AD)
(LITERAL ,INFINITUM)))
T
Note the sly placement of commas within the pattern denoted by LITERAL. I have tried dozens of
backquote-comma combinations but can't find the right one.
Any responses will be greatly appreciated.
Len Charest, charest@ai-sun.jpl.nasa.gov
This works for me, although I can't call it perpicuous.
1(defmacro macro-maker (name arglist) ;name and will become part of the inner macro's template
`(defmacro ,name ,arglist
0 ;;the function some-function takes multiple literal patterns (ie. lists) as its arguments
;;assume the lists are self-quoting
1 `(some-function
0,1,@(loop for arg in arglist
0 1collect0 ``1(0literal1 0,,1arg)))))