When creating mixed-language .Rmd documents with knitr, I sometimes use a prompt to make it clear which language is being used in a particular chunk. I recently tried this with a julia language chunk using the JuliaCall package and noticed some strange behavior when I used a semicolon ; to suppress output.
Here's a minimal example:
---
output: html_document
---
```{r setup, echo = FALSE}
knitr::opts_chunk$set(echo = TRUE)
knitr::opts_chunk$set(prompt = TRUE)
```
```{r, echo = FALSE}
options(prompt = "julia> ")
```
```{julia}
x = 3;
3x
```
```{julia, prompt = FALSE}
x = 3;
3x
```
```{r, echo = FALSE}
options(prompt = "R> ")
```
```{r}
x <- 3
3 * x
```
The resulting output was as follows:
In the first julia chunk, knitr seems to be interpreting the semicolon as R syntax: it adds a + to break the input line. In the second, when I remove the prompt, this is no longer the case. I'd like to obtain the same output as I get from the second chunk except with a julia> preceding each line of code. In other words, I'd like the same output as in my final R chunk except with julia replacing R. I'd very much appreciate any suggestions you may have.
Here's my session info for reference:
## ─ Session info ───────────────────────────────────────────────────────────────
## setting value
## version R version 4.0.5 (2021-03-31)
## os Ubuntu 20.04.2 LTS
## system x86_64, linux-gnu
## ui X11
## language en_US:en
## collate en_US.UTF-8
## ctype en_US.UTF-8
## tz ---
## date 2021-04-20
##
## ─ Packages ───────────────────────────────────────────────────────────────────
## package * version date lib source
## bslib 0.2.4 2021-01-25 [1] CRAN (R 4.0.3)
## cachem 1.0.4 2021-02-13 [1] CRAN (R 4.0.5)
## callr 3.6.0 2021-03-28 [1] CRAN (R 4.0.5)
## cli 2.4.0 2021-04-05 [1] CRAN (R 4.0.5)
## crayon 1.4.1 2021-02-08 [1] CRAN (R 4.0.5)
## desc 1.3.0 2021-03-05 [1] CRAN (R 4.0.5)
## devtools 2.4.0 2021-04-07 [1] CRAN (R 4.0.5)
## digest 0.6.27 2020-10-24 [1] CRAN (R 4.0.3)
## ellipsis 0.3.1 2020-05-15 [1] CRAN (R 4.0.3)
## evaluate 0.14 2019-05-28 [1] CRAN (R 4.0.3)
## fastmap 1.1.0 2021-01-25 [1] CRAN (R 4.0.3)
## fs 1.5.0 2020-07-31 [1] CRAN (R 4.0.3)
## glue 1.4.2 2020-08-27 [1] CRAN (R 4.0.3)
## htmltools 0.5.1.1 2021-01-22 [1] CRAN (R 4.0.3)
## jquerylib 0.1.3 2020-12-17 [1] CRAN (R 4.0.3)
## jsonlite 1.7.2 2020-12-09 [1] CRAN (R 4.0.3)
## JuliaCall 0.17.2 2021-01-04 [1] CRAN (R 4.0.5)
## knitr 1.32 2021-04-14 [1] CRAN (R 4.0.5)
## lifecycle 1.0.0 2021-02-15 [1] CRAN (R 4.0.5)
## magrittr 2.0.1 2020-11-17 [1] CRAN (R 4.0.3)
## memoise 2.0.0 2021-01-26 [1] CRAN (R 4.0.5)
## pkgbuild 1.2.0 2020-12-15 [1] CRAN (R 4.0.3)
## pkgload 1.2.1 2021-04-06 [1] CRAN (R 4.0.5)
## prettyunits 1.1.1 2020-01-24 [1] CRAN (R 4.0.3)
## processx 3.5.1 2021-04-04 [1] CRAN (R 4.0.5)
## ps 1.6.0 2021-02-28 [1] CRAN (R 4.0.5)
## purrr 0.3.4 2020-04-17 [1] CRAN (R 4.0.3)
## R6 2.5.0 2020-10-28 [1] CRAN (R 4.0.3)
## Rcpp 1.0.6 2021-01-15 [1] CRAN (R 4.0.5)
## remotes 2.3.0 2021-04-01 [1] CRAN (R 4.0.5)
## rlang 0.4.10 2020-12-30 [1] CRAN (R 4.0.5)
## rmarkdown 2.7 2021-02-19 [1] CRAN (R 4.0.5)
## rprojroot 2.0.2 2020-11-15 [1] CRAN (R 4.0.3)
## sass 0.3.1 2021-01-24 [1] CRAN (R 4.0.3)
## sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 4.0.3)
## stringi 1.5.3 2020-09-09 [1] CRAN (R 4.0.3)
## stringr 1.4.0 2019-02-10 [1] CRAN (R 4.0.3)
## testthat 3.0.2 2021-02-14 [1] CRAN (R 4.0.5)
## usethis 2.0.1 2021-02-10 [1] CRAN (R 4.0.5)
## withr 2.4.2 2021-04-18 [1] CRAN (R 4.0.5)
## xfun 0.22 2021-03-11 [1] CRAN (R 4.0.5)
## yaml 2.2.1 2020-02-01 [1] CRAN (R 4.0.3)
##
## [1] /home/inhuretnakht/R/x86_64-pc-linux-gnu-library/4.0
## [2] /usr/local/lib/R/site-library
## [3] /usr/lib/R/site-library
## [4] /usr/lib/R/library