Re: local syntax-rules

[Lars J. Aas]

On Mon, Nov 06, 2000 at 05:14:08PM +0100, Lars J. Aas wrote:
:   (define-syntax argtypes
:     (let-syntax ((argtype (syntax-rules ()
:                             ((argtype (name type)) type)
:                             ((argtype name) <top>))))
:       (syntax-rules ()
:         ((argtypes arg) (cons (argtype arg) '()))
:         ((argtypes arg arg1 ...) (cons (argtype arg) (argtypes arg1 ...))))))
: 
: Should I use let-syntax in another way (e.g. *inside* the argtypes 
syntax-rules)?

I found putting them inside the rules to work:

  (define-syntax argtypes
    (syntax-rules ()
      ((argtypes arg)
        (let-syntax ((argtype (syntax-rules ()
                                ((argtype (name type)) type)
                                ((argtype name) <top>))))
          (cons (argtype arg) '())))
      ((argtypes arg arg1 ...)
        (let-syntax ((argtype (syntax-rules ()
                                ((argtype (name type)) type)
                                ((argtype name) <top>))))
          (cons (argtype arg) (argtypes arg1 ...))))))

However, this makes me have to repeat the submacros for each public syntax-rule,
making the whole thing an unreadable mess.  Isn't a shared approach (like the
invalid example on top) possible?  I tried to enclose the syntax rules through
let-variables, but that didn't work either:

  (define-syntax argtypes
    (let ((argtype-rules (syntax-rules ()
                           ((argtype (name type)) type)
                           ((argtype name) <top>))))
      (syntax-rules ()
        ((argtypes arg)
          (let-syntax (argtype argtype-rules)
            (cons (argtype arg) '())))
        ((argtypes arg arg1 ...)
          (let-syntax (argtype argtype-rules)
            (cons (argtype arg) (argtypes arg1 ...)))))))

Any suggestions?  I'll rather use public sub-macros than the let-syntax approach
I found to work...

  Lars J