Export is_promise2

[blmoore]

I found is_promise2 via this SO answer and it seems to be the only way to check that delayedAssign is working as expected outside of the GlobalEnv. Is there a reason it's not exported?

My use case:

e <- new.env(parent = emptyenv())
delayedAssign("var", 1:1e10, assign.env = e)

pryr::is_promise(e$var)
# Error: cannot convert to symbol (SYMSXP)

pryr:::is_promise2("var", e)
# [1] TRUE