Negative numbers are not syntactic literals

[moodymudskipper]

Since they use -.

We dismiss complex numbers with a real part, presumably because of the +, so it would make sense to return FALSE for negative integer, double, and imaginary numbers.

x <- quote((-1))
y <- substitute((X), list(X = -1))
x
#> (-1)
y
#> (-1)
typeof(x[[2]])
#> [1] "language"
typeof(y[[2]])
#> [1] "double"
rlang::is_expression(x) # correct
#> [1] TRUE
rlang::is_expression(y) # incorrect
#> [1] TRUE

Related: rlang::is_syntactic_literal(NA + 1i) is currently TRUE, to be a syntactic literal a complex number must have a real part of 0.

[lionel-]

I'm tempted to deprecate this functionality as we don't use it for anything important and it sounds like a pain to keep maintaining it.

Would you have any interest in taking over these functions and maintaining them in another package?

[moodymudskipper]

In constructive I have already is_expression2() and is_syntactic_litteral2(), both unexported, which are mostly similar, though I don't think I based the former on yours directly. I need those so i can generate the code to construct language objects faithfully. I can remove the "2", make sure they pass rlang's own tests and export them there, but don't you need those in rlang for expr_deparse() and friends ?