Re: [Lush-users] Nested anonymous functions

[Fabian <fb...@t-...>]

Hallo Ralf,

I have taken a look at it and it can very easily be extended for
nested lambda expression. Its just one simple addition:

(consp expr) -> (and (consp expr) (<> 'lambda (car expr)))

which ensures, that he doesn't parses the arguments of nested
lambdas.
You can find the changes  below, plus one trivial fix when you have
a lambda without arguments.

with best regards,
Fabian

;;---------------------------

(defun lambda-largest-positional-arg (expr)
  (if (and (consp expr) (<> 'lambda (car expr)));;<-----
      (apply max 0 (mapcar lambda-largest-positional-arg expr))
    (or (*lambda-positional-symbol* expr) 0) ))

(defun lambda-has-ellipsis (expr)
  (if (and (consp expr) (<> 'lambda (car expr)));;<-----
      (apply or (mapcar lambda-has-ellipsis expr))
    (= expr '..) ))

(defun lambda-ellipsify (expr)
  (if (and (consp expr) (<> 'lambda (car expr)));;<-----
      (let (((head . tail) expr))
        (if (= head '..)
            (if tail
                (error 'lambdafy "syntax-error: ellipsis must terminate s-expression")
              '..)
          (cons (lambda-ellipsify head) (lambda-ellipsify tail)) ))
    expr))

(defun lambdafy (expr)
  (let ((n (lambda-largest-positional-arg expr)))
    (if (lambda-has-ellipsis expr)
        (if (> n 0)
            (let ((args (domapcar ((i (range n)))
                          (symbol-concat '$ (named (str i))))))
              (rplacd (last args) '..)
              `(lambda ,args ,(lambda-ellipsify expr)) )
          `(lambda .. ,(lambda-ellipsify expr)) )
      `(lambda (,@(domapcar ((i (if (= n 0) () (range n))));;<-----
                    (symbol-concat '$ (named (str i)))) )
         ,expr)
      )))
On Thu, May 20, 2010 at 07:28:24AM -0700, Ralf Juengling wrote:
>
> Hm, I never thought about nested lambdas when I wrote the compact
> lambda macro. While I think it's probably better to define a function
> when lambdas become more complicated, this is clearly a bug in the
> macro.
>
> It might take me a while before I have time to look at it. If you
> want to take a shot at fixing it, the definition is in sys/sysenv.lsh.
>
> Thanks for reporting,
> Ralf
>