highlight is a syntax highlighter for R code.

You can install highlight from github with:

# install.packages("devtools")
devtools::install_github("romainfrancois/highlight")

Typical syntax highlighting is only interested in whether a token is a function call, a keyword, a string, ... this is what the lestrade detective does:

highlight( file = "css_file.R", detective = lestrade )

This will look like this:

This differentiates function calls, formal arguments, used arguments ... because lestrade identified these tokens as such.

Traditional highlighting only reveals the obvious, so the package also benefits from the investigation of sherlock for semantic highlighting. In semantic highlighting, every symbol gets a different color.

highlight( file = "css_file.R", detective = sherlock )

With this we can quickly skim through the file and see e.g. the different uses of filename.

To use in rmarkdown you can use the hl_hook_source and hl_hook_document hooks. Unfortunately this does not work for README on github so this document uses screenshots.

knitr::knit_hooks$set( 
  source = hl_hook_source, 
  document = hl_hook_css
)