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<font face="Helvetica, Arial, sans-serif">Hi Louis,<br>
<br>
I believe the problem is not finding useful applications for the
not yet exploited valence variants of APL primitives.<br>
Every such extension of the APL syntax creates a new
incompatibility and should be avoided in the first place.<br>
<br>
If I remember correctly then there was only one case so far where
a primitive in GNU APL was extended beyond what<br>
IBM APL2 provides: monadic ⍳ for higher ranks (taken from Dyalog
APL). That extension was actually simplifying APL because<br>
it was removing a historical limitation of monadic ⍳ and made it
more general. Using <b>↓</b> for <font face="Courier New,
Courier, monospace"><b>¯1↑</b></font> is, IMHO, not entirely
convincing<br>
and could confuse people more than it helps.<br>
<br>
Best Regards,<br>
/// Jürgen<br>
<br>
</font><br>
<div class="moz-cite-prefix">On 10/10/2017 08:06 PM, Louis de
Forcrand wrote:<br>
</div>
<blockquote type="cite"
cite="mid:7AA368E3-80EB-416F-BC27-***@bluewin.ch">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
Since the subject has been brought up, how about using it as the
analog of first (monadic take), but instead unboxing the last
element of an array in ravel order?
<div><br>
</div>
<div>I don’t think this can generally be done on an array X in a
more concise way than </div>
<div>first reverse ravel X</div>
<div>or</div>
<div>(shape X) pick X</div>
<div>which I suppose are both slower than a primitive could be.</div>
<div>This might be considered trivial as well though.</div>
<div><br>
</div>
<div>Just a suggestion!</div>
<div>Louis</div>
<div>
<div><br>
On 10 Oct 2017, at 18:46, Juergen Sauermann <<a
href="mailto:***@t-online.de"
moz-do-not-send="true">***@t-online.de</a>>
wrote:<br>
<br>
</div>
<blockquote type="cite">
<div>
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charset=utf-8">
<font face="Helvetica, Arial, sans-serif">Hi Elias,<br>
<br>
I believe ↓ for 1↓ is too trivial to be useful.<br>
<br>
Unoccupied variants of APL primitives (like monadic ↓ or
monadic =) are<br>
a very scarce resource that we should not use for trivial
things.<br>
</font><br>
/// Jürgen<br>
<br>
<br>
<div class="moz-cite-prefix">On 10/09/2017 11:06 AM, Elias
Mårtenson wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CADtN0W+E1UoE+vbPQCB4-***@mail.gmail.com">
<div dir="ltr">I was thinking about the usefulness of a
monadic ↓ in terms of the new regexp feature. In the
current version, when using subexpressions, the return
value is always 1+the number of subexpressions, where
the first one is always the full matched string.
Monadic ↓ would be a neat way of dropping that part.
<div><br>
</div>
<div>In any case, my point is that monadic ↓ should do
something useful. I guess split is one such useful
thing.</div>
<div><br>
</div>
<div>In GNU APL, I'd use ⊂⍤1 to achieve Split. Is that
the most efficient way?</div>
<div><br>
</div>
<div>Regards,</div>
<div>Elias</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On 9 October 2017 at 16:58, Jay
Foad <span dir="ltr"><<a
href="mailto:***@gmail.com" target="_blank"
moz-do-not-send="true">***@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote"><span class="">On 9
October 2017 at 04:56, Elias Mårtenson <span
dir="ltr"><<a
href="mailto:***@gmail.com"
target="_blank" moz-do-not-send="true">***@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Currently, monadic ↑ acts
as if it was called dyadically with 1 as
its left argument,</div>
</blockquote>
<div><br>
</div>
</span>
<div>That's not quite true:</div>
<div>
<div><br>
</div>
<div> ⍴⍴1↑'ABC'</div>
<div>1</div>
<div> ⍴⍴↑'ABC'</div>
<div>0</div>
</div>
<span class="">
<div><br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr"> while monadic ↓ raises a
VALENCE ERROR. In almost every single
case where I have used ↓, it has been in
the form 1↓X. Is there a reason why the
monadic form is not allowed?</div>
</blockquote>
<div><br>
</div>
</span>
<div>FYI in Dyalog APL monadic ↓ is Split:</div>
<div>
<div><br>
</div>
<div> ↓3 3⍴⎕A</div>
<div>┌───┬───┬───┐</div>
<div>│ABC│DEF│GHI│</div>
<div>└───┴───┴───┘</div>
</div>
<div><br>
</div>
<div>I believe this came from STSC's NARS.<span
class="HOEnZb"><font color="#888888"><br>
</font></span></div>
<span class="HOEnZb"><font color="#888888">
<div><br>
</div>
<div>Jay.</div>
</font></span></div>
</div>
</div>
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