Semantic Highlighting & Pretty Printing

Since v0.9.18 Idris comes with support for semantic highlighting. When using the REPL or IDE support, Idris will highlight your code accordingly to its meaning within the Idris structure. A precursor to semantic highlighting support is the pretty printing of definitions to console, LaTeX, or HTML.

The default styling scheme used was inspired by Conor McBride’s own set of stylings, informally known as Conor Colours.


The concepts and their default stylings are as follows:

Bound Variable Purple Magenta  
Keyword Bold Underlined  
Function Green Green  
Type Blue Blue  
Data Red Red  
Implicit Italic Purple Italic Magenta  

Pretty Printing

Idris also supports the pretty printing of code to HTML and LaTeX using the commands:

  • :pp <latex|html> <width> <function name>
  • :pprint <latex|html> <width> <function name>


If you are not happy with the colours used, the VIM and Emacs editor support allows for customisation of the colours. When pretty printing Idris code as LaTeX and HTML, commands and a CSS style are provided. The colours used by the REPL can be customised through the initialisation script.

Further Information

Please also see the Idris Extras project for links to editor support, and pre-made style files for LaTeX and HTML.