# Richard Stallman

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*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

- ↑ Stallman, Richard M. "RMS Berättar".
- ↑ Stallman, Richard M. "Doggerel"