hlterm: Send code to Neovim's terminal and highlight the output

Notes:

• hlterm is the vimcmdline plugin converted from VimScript to Lua.

• hlterm only works in Neovim, but Vim users can use the branch "vim".

This plugin sends lines from Neovim to a command line interpreter (REPL application). There is support for Clojure, Golang, Haskell, JavaScript, Julia, Jupyter, Kotlin, Lisp, Lua, Macaulay2, Matlab, Prolog, Python, R, Racket, Ruby, Sage, Scala, Shell script, Swift, Kdb/q and TypeScript (see R.nvim for a more compreehsive support for R in Neovim). If the file type is quarto, hlterm will try to infer what interpreter should be started.

The interpreter runs in Neovim's built-in terminal. If Tmux or Zellij is installed, the interpreter can also run in an external terminal emulator (tmux-only) or in a tmux/zellij pane. The main advantage of running the interpreter in a Neovim terminal is that the output is colorized, as in the screenshot below, where we have different colors for general output, positive and negative numbers, and the prompt line:

If running in either a Neovim built-in terminal or an external terminal, the plugin runs one instance of the REPL application for each file type. If running in a tmux or zellij pane, it runs one REPL application for Neovim instance.

How to install

Use a plugin manager to install hlterm.

You need to install either Tmux or Zellij if you want to run the interpreter in a split pane. Note that external terminal emulator support requires Tmux specifically.

Usage and options

In Normal mode, type <LocalLeader>s to start the interpreter.

Please, read the plugin's documentation for further instructions.

How to add support for a new language

1. Look at the Lua scripts in the ftplugin directory and make a copy of the one closer to the language that you want to support.

2. Save the new script with the name "filetype_hlterm.lua" where "filetype" is the output of :echo &filetype when you are editing a script of the language that you want to support.

3. Edit the new script and change the values of its variables as necessary.

4. Test your new file-type script by running your application in Neovim.

5. Test your new output highlighting by running your application in a Neovim built-in terminal.

When editing your new file-type script, keep in mind that the goal is to highlight the output, not the language. The code is properly highlighted in the editor. In the terminal, we want to focus in the output and not be distracted by a colorful input. Change the patterns used to recognize the input line, errors, warnings, and the keywords that identify boolean values and constants (such as None in Python, nil in Lua, and NULL and NA in R).

String delimiters are not what the language accepts as input, but what it outputs. For example, in Python

txt = "abc"
txt

outputs 'abc' while in R

txt <- 'abc'
txt

outputs [1] "abc". Hence, the string delimiter is ' in Python and " in R.

See also

Similar plugins are toggleterm.nvim, iron.nvim, vim-slime, neoterm, sniprun, conjure, and yarepl.nvim.