Essays/Self

"Write a program that prints its own source code".

See the catalog at Puzzles/Quine

In J that would be "write an expression that results in a string composed of the same characters in the same sequence as the original expression".

Another way to say it is to define a string s such that (-: ".)s

It can be debated whether the empty string counts as a J expression and therefore is an allowable entry, so to reduce trivial discussion let's assume non-empty s.

Here is a solution:

(,~,{:,{:)'(,~,{:,{:)'''

And another one:

(,{:)^:2,~'(,{:)^:2,~'''

And this one has the same length (24 characters) now but may be reduced to 22 in (future) J6

(,2:#{:),~'(,2:#{:),~'''

Can there be shorter expressions with this property?

Is it possible to construct expression with this property that has odd number of characters?