Function Rf_lang1 

pub unsafe fn Rf_lang1(s: SEXP) -> SEXP

Build a language object (call) with 1 element (the function).

Rust equivalent of R’s inline Rf_lang1(s). Creates a call like f() where s is the function.

Safety

• s must be a valid SEXP (typically a symbol or closure)
• Must be called from R’s main thread
• Result must be protected from GC