Richard Stallman: Difference between revisions

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'''Richard Matthew Stallman''', founder of the GNU Project, was an early adopter of APL, and used it to write a text editor as a high school student in the summer of 1969<ref>Stallman, Richard M. [http://www.lysator.liu.se/history/garb/txt/87-2-rms.txt "RMS Berättar"].</ref>. The same year, he also wrote a now famous rhyme:
'''Richard Matthew Stallman''', founder of the GNU Project, was an early adopter of APL, and used it to write a text editor as a high school student in the summer of 1969<ref>Stallman, Richard M. [http://www.lysator.liu.se/history/garb/txt/87-2-rms.txt "RMS Berättar"].</ref>. The same year, he also wrote a now famous rhyme:
<blockquote>Rho, rho, rho of X<br>Always equals 1<br>Rho is dimension, rho rho rank.<br>APL is fun!<ref>Stallman, Richard M. [https://stallman.org/doggerel.html#APL "Doggerel"]</ref></blockquote>
<blockquote>Rho, rho, rho of X<br>Always equals 1<br>Rho is dimension, rho rho rank.<br>APL is fun!<ref>Stallman, Richard M. [https://stallman.org/doggerel.html#APL "Doggerel"]</ref></blockquote>
This plays on the fact that <syntaxhighlight lang=apl inline>⍴X</source> gives the [[shape]] (length of each [[axis]]; "dimension") of <syntaxhighlight lang=apl inline>X</source> while <syntaxhighlight lang=apl inline>⍴⍴X</source> gives the [[rank]] (number of axes/dimensions) and since the number of axes is always a count, it is a single number, which has the shape <syntaxhighlight lang=apl inline>1</source> if a [[vector]], and <syntaxhighlight lang=apl inline>⍴</source> always returns a vector:
This plays on the fact that <syntaxhighlight lang=apl inline>⍴X</syntaxhighlight> gives the [[shape]] (length of each [[axis]]; "dimension") of <syntaxhighlight lang=apl inline>X</syntaxhighlight> while <syntaxhighlight lang=apl inline>⍴⍴X</syntaxhighlight> gives the [[rank]] (number of axes/dimensions) and since the number of axes is always a count, it is a single number, which has the shape <syntaxhighlight lang=apl inline>1</syntaxhighlight> if a [[vector]], and <syntaxhighlight lang=apl inline>⍴</syntaxhighlight> always returns a vector:


<syntaxhighlight lang=apl>
<syntaxhighlight lang=apl>
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       ⍴⍴⍴X
       ⍴⍴⍴X
1
1
</source>
</syntaxhighlight>


== References ==
== References ==

Latest revision as of 21:54, 10 September 2022

This article is about Stallman's relationship with APL. For more complete information about Stallman, see Wikipedia.

Richard Matthew Stallman, founder of the GNU Project, was an early adopter of APL, and used it to write a text editor as a high school student in the summer of 1969[1]. The same year, he also wrote a now famous rhyme:

Rho, rho, rho of X
Always equals 1
Rho is dimension, rho rho rank.
APL is fun![2]

This plays on the fact that ⍴X gives the shape (length of each axis; "dimension") of X while ⍴⍴X gives the rank (number of axes/dimensions) and since the number of axes is always a count, it is a single number, which has the shape 1 if a vector, and always returns a vector:

      ⎕←X←3 1 4∘.+2 7 1 8
5 10 4 11
3  8 2  9
6 11 5 12
      ⍴X
3 4
      ⍴⍴X
2
      ⍴⍴⍴X
1

References

  1. Stallman, Richard M. "RMS Berättar".
  2. Stallman, Richard M. "Doggerel"
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