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rquine

Constructing quines (self-reproducing functions)

Has anyone constructed a quine ("A program that generates a copy of its own source text as its complete output": http://www.nyx.net/~gthompso/quine.htm) in R? (The [quine] tag pulls up lots of examples in Python, Java, ... but apparently none in R.)

f <- function() { body() }

comes close:

> f()
{
    body()
}

but lacks the name of the function.

How about the shortest possibility? Most obfuscated?

edit: from the variety of answers below, it seems that there are a variety of ways to define self-referentiality and the environment in which it must occur:

  • within the R environment: function -> function (@bill_080)
  • within the OS/shell environment: program -> program [more or less equivalent to program -> text]: (@kohske)
  • other: function -> text (@JoshUlrich, @James, problem as defined above)

Notes:

  • The thread from R-help pointed out by @Spacedman (which seems to emphasize obfuscation over brevity) suggests that identical(quine,quine()) is a good test case, although it's tricky because environments get carried along: identical(quine,quine(),ignore.environment=TRUE) might be easier.
  • A recent (Oct 2015) blog post provides another answer ...
Solution

  • This is the shortest I can come up with:

    > "f" <- function() call("<-", "f", f)
> f()
"f" <- function () 
call("<-", "f", f)