R version 4.5.0 RC (2025-04-03 r88103 ucrt) -- "How About a Twenty-Six"
Copyright (C) 2025 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> # issue spotted by Alexandre Sieira
> # and his example code.
> library(RJSONIO)
> 
> fromJSON("[ 1, null, 4 ]", asText = TRUE, simplify = TRUE)
[1]  1 NA  4
> fromJSON('[ "a", null, "d" ]', asText = TRUE, simplify = TRUE)
[1] "a" NA  "d"
> 
> fromJSON("[ 1, null, 4 ]", asText = TRUE, simplify = TRUE, nullValue = -999L)
[1]    1 -999    4
> fromJSON('[ "a", null, "d" ]', asText = TRUE, simplify = TRUE, nullValue = "999")
[1] "a"   "999" "d"  
> 
> proc.time()
   user  system elapsed 
   0.14    0.03    0.15