[iterate-devel] defclause-driver with &sequence

[Venkatesan S]

Sorry, I meant defmacro-driver everywhere I mentioned defclause-driver in
the last mail :(

On Sun, Jan 23, 2011 at 7:14 PM, Venkatesan S <svtesan at gmail.com> wrote:

> Hi,
>
> I was trying to roll an iterate driver for iterating over dates and I am
> stuck with a problem. When using defmacro-driver, I am unable to get the
> value passed in from to and other sequence classes. I tried with the example
> given in the manual (chapter "Rolling your own"), but hit the same problem.
> The manual says:
> "We can now refer to parameters from, to, by, etc. which contain either the
> values for
> the corresponding keyword, or nil if the keyword was not supplied.
> Implementing the right
> code for these keywords is cumbersome but not difficult; it is left as an
> exercise."
>
> But I guess I am one of the dumb few who failed the exercise :)) The
> following is my attempt with the example given in the manual:
>
> (defmacro-driver (FOR var IN-WHOLE-VECTOR v &sequence)
>       "All the elements of a vector (disregards fill-pointer)"
>       (let ((vect (gensym))
>               (end (gensym))
>               (index (gensym))
>               (myfrm (gensym "myfrm"))
>               (kwd (if generate 'generate 'for)))
>               `(progn
>                             (with ,vect = ,v)
>                             (with ,myfrm = ,from)
>                             (with ,end = (array-dimension ,vect 0))
>                             (with ,index = -1)
>                             (,kwd ,var next (progn (incf ,index)
>                             (if (>= ,index ,end) (terminate))
>                                           (format t "myfrm: ~a~%" ,myfrm)
>                                           (aref ,vect ,index))))))
>
>  I tried using the driver with: (a is an array of 10 elements)
> (iter (for v in-whole-vector a from 5 below 8)
>                  (print v))
>
> I get the following error:
>  The variable FROM is unbound.
>    [Condition of type UNBOUND-VARIABLE]
>
> Restarts:
>  0: [RETRY] Retry SLIME REPL evaluation request.
>  1: [*ABORT] Return to SLIME's top level.
>  2: [ABORT] Exit debugger, returning to top level.
>
> Backtrace:
>   0: ((DEFMACRO CLAUSE-FOR-IN-WHOLE-VECTOR-18)
> (CLAUSE-FOR-IN-WHOLE-VECTOR-18 :FOR V :IN-WHOLE-VECTOR A :FROM ...) #<unused
> argument>)
>   1: (MACROEXPAND-1 (CLAUSE-FOR-IN-WHOLE-VECTOR-18 :FOR V :IN-WHOLE-VECTOR
> A :FROM ...) #<NULL-LEXENV>)
>   2: (ITERATE::PROCESS-CLAUSE (FOR V IN-WHOLE-VECTOR A FROM 5 ...))
>   3: (ITERATE::WALK (FOR V IN-WHOLE-VECTOR A FROM 5 ...))
>   4: (ITERATE::WALK-LIST-NCONCING ((FOR V IN-WHOLE-VECTOR A FROM 5 ...)
> (PRINT V)) #<FUNCTION ITERATE::WALK> #<FUNCTION (LAMBDA #) {100407D489}>)
>   5: (ITERATE::WALK-LIST ((FOR V IN-WHOLE-VECTOR A FROM 5 ...) (PRINT V)))
>   6: ((DEFMACRO ITER) ..)
>
> I am using ubuntu maverick, 10.10, SBCL 1.0.45 64 bit.
>
> I tried the following:
> (with ,myfrm = from)
>
>  I get an error:
> The variable FROM is unbound.
>    [Condition of type UNBOUND-VARIABLE]
>
> Restarts:
>  0: [RETRY] Retry SLIME REPL evaluation request.
>  1: [*ABORT] Return to SLIME's top level.
>  2: [ABORT] Exit debugger, returning to top level.
>
> Backtrace:
>   0: ((LAMBDA ()))
>   1: (SB-INT:SIMPLE-EVAL-IN-LEXENV ..)
>   2: (SWANK::EVAL-REGION "(iter (for v in-whole-vector a from 5 below
> 8)\n                 (print v))\n")
>   3: ((LAMBDA ()))
>
>
> 2) (with ,myfrm = :from)
> This does not throw any error, but just prints
> myfrm: FROM
> instead of the value given
>
> I want to use defclause-driver with the sequence keywords, I could not
> figure out how to get the values passed in from, to and other such clauses.
> Can anyone please provide some pointers?
>
>
>
> --
> Audentis fortuna juvat
>



-- 
Audentis fortuna juvat
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