Re: Implementation of DELETE-FROM-PLIST

Apologies to Robert for stealing his thunder.

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Re: Implementation of DELETE-FROM-PLIST

Looks good! Much cleaner/better.

-Robert

On Sun, Feb 24, 2013 at 6:30 AM, James M. Lawrence <llmjjmll <at> gmail.com> wrote:
> On Sat, Feb 23, 2013 at 4:09 AM, Robert Smith <quad <at> symbo1ics.com> wrote:
>>
>> (defun delete-from-plist (plist &rest keys)
>>   "Delete all keys and pairs indicated by KEYS from the plist PLIST."
>>   (labels ((assert-proper-plist (x)
>>              (assert x () "Expected a proper plist, got ~S" plist))
>>            (bad-key-p (key)
>>              (member key keys :test #'eq))
>>            (find-first ()
>>              "Find the first cons in PLIST to keep."
>>              (loop :for the-cons :on plist :by #'cddr
>>                    :unless (prog1 (bad-key-p (car the-cons))
>>                              (assert-proper-plist (cdr the-cons)))
>>                      :do (return the-cons)
>>                    :finally (return nil))))
>>     (declare (inline assert-proper-plist
>>                      bad-key-p
>>                      find-first))
>>     ;; Find the first good key and delete any bad key-value pairs
>>     ;; between it and the start.
>>     (let ((first (find-first)))
>>       (unless (eq first plist)
>>         (setf (cddr plist)
>>               first))
>>

Re: Implementation of DELETE-FROM-PLIST

"James M. Lawrence" <llmjjmll <at> gmail.com> writes:

> Using two loops seems awkward to me. How about one?
>
> (defun delete-from-plist (plist &rest keys)
>   (loop with head = plist
>         with tail = nil
>         for (key . rest) on plist by #'cddr
>         do (assert rest () "Expected a proper plist, got ~S" plist)
>            (if (member key keys :test #'eq)
>                (let ((next (cdr rest)))
>                  (if tail
>                      (setf (cdr tail) next)
>                      (setf head next)))
>                (setf tail rest))
>         finally (return head)))

I mention this for completeness and novelty, not for suitability:

  (defun sans (plist &rest keys)
    (let ((sans ()))
      (loop
        (let ((tail (nth-value 2 (get-properties plist keys))))
          ;; this is how it ends
          (unless tail
            (return (nreconc sans plist)))
          ;; copy all the unmatched keys
          (loop until (eq plist tail) do
                (push (pop plist) sans)
                (push (pop plist) sans))

Implementation of DELETE-FROM-PLIST

Hey:

Here's a destructive/non-consing version of DELETE-FROM-PLIST. I've
tested with (I think) all corner cases from the REPL, but I ought to
write tests proper.

The function is here http://tinyurl.com/adqkssu ;or the following huge
link, in case the last one is invalidated
https://bitbucket.org/tarballs_are_good/lisp-random/src/3db634111d35e788c6ea2f4a1b3ab38334e24cde/miscellaneous_exercises/delete-from-plist.lisp?at=default#cl-30
.

For simplicity or ease of review from an email client, I've pasted the
function at the end of this email.

Additionally, this function would make it pretty easy to write
DELETE-FROM-PLIST-IF{-NOT}, since the function to determine if a key
is bad is factored out. If one did write this function, then it would
be easy to define DELETE-FROM-PLIST in terms of it.

Let me know if there are any changes that should be made.

Cheers,

Robert Smith

;;;; from delete-from-plist.lisp

(defun delete-from-plist (plist &rest keys)
  "Delete all keys and pairs indicated by KEYS from the plist PLIST."
  (labels ((assert-proper-plist (x)

Bug in gaussian-random

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More open development

On Sat, Jan 26, 2013 at 9:14 AM, Nikodemus Siivola
<nikodemus <at> random-state.net> wrote:
> On 6 November 2012 07:26, Faré <fahree <at> gmail.com> wrote:
>
>> And/or I want another library in which utilities can be speedily updated.
>
> Speed of evolution is an explicit non-goal for Alexandria. Also,
> please don't hijack threads.
>
Maybe alexandria needs more people with commit rights?

Or else, maybe we need a different reference library that will have
a more open development style.

—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org
Government's view of the economy could be summed up in a few short phrases :
If it moves, tax it. If it keeps moving, regulate it. And if it stops
moving, subsidize it. — Ronald Reagan (1986)

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flatten depth param

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if-let*

(i think i've already sent this, but it hasn't shown up on the list,
sorry if you get it twice)

hi,

  i recently needed (or just decided that i wanted it) a version of
  if-let with sequential binding. The bindings form is as with if-let,
  however to ensure that only the 'true' bindings are seen in the else
  form (and i'm not convinced this is worth it) the else form is
  repeated multiple times (once per binding) in the macro's expansion.

  the docstring should explain how it works (and if not i'll fix the
  docstring).

  and, since it made sense to me at the time, when-let and when-let* are
  implemented in terms of if-let and if-let* (instead of repeating the
  binding expansion and and code).

--
-marco

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multiple values in switch clauses

hi,

  i'd like switch to, just like case and typecase do, allow multiple
  values in the 'value' position of the condition:

  (switch (foo)
    ((bar baz) ...))

  So the attached patch checks for the key form being a cons and, if so,
  expands into a (member value :test test) instead of (test value)
  form. Of course, this means that your key values can no longer be
  forms, so this may break existing code. I don't have any code which
  actually uses a function call in the value form of the clause (and a
  quick grep over my locally installed lisp libs shows nobody else does
  either), so i'm ok with the change, but i can understand if others
  don't agree.

--
-marco

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Add SUBDIVIDE to alexandria

Hello all,

What are the odds of adding this[1] implementation of SUBDIVIDE to
alexandria?

I understand that alexandria only accepts public domain code, but I
think that Robert Smith also follows this mailist so maybe he would
let the code be added to alexandria.

SUBDIVIDE is a function that divides a sequence into parts with a
certain size, and returns a list with those parts.

Best Regards,
Rolando Pereira

---
Links:

[1] - https://bitbucket.org/tarballs_are_good/qtility/src/423519bbe130/sequence.lisp#cl-29

http://common-lisp.net/project/alexandria/

Hi.

http://common-lisp.net/project/alexandria/ 

has a reference to "draft documantion exists" when it probably means
"draft documentation" exists?

Michael