Vim: How to manipulate appearance of signs in .vimrc?

Question

I have seen a guy on YouTube who has some sort of Markdown rendering in Vim.

The * sign from a list is displayed as a •.
When the cursor travels over it, the actual sign shows up.
I have checked his .vimrc on GitLab, but couldn't find anything matching.
He loads a lot of plugins there, so I think it comes from one of those.

• Can something like this be scripted directly in the .vimrc?
• Or where and how would I script something like this?

Here is the mentioned vimrc

Answer 1

This is probably concealing.

The first thing you'll have to do is to identify the syntax group of the character you want to transform.

As an example, let's take this typescript code:

/**
 * This function makes the sum of its arguments.
 *
 * @param nums The list of numbers to add together
 *
 * @return The sum of the given numbers
 */
function add(...nums: number[]) {
    return nums.reduce((acc, num) => acc + num, 0);
}

And let's say I want to transform the @param and @return to ⦿ and ↩.

First, I can Identify the syntax group using this vimscript function:

function! GetGroupName()
    if !exists("*synstack") | return | endif
    echo map(synstack(line('.'), col('.')), 'synIDattr(v:val, "name" )')
endfunction

You can use it by typing :echo GetGroupName() when your cursor is on the word/character to transform.

---

Once you have the group , in my case typescriptDocComment, I simply need to enter:

syntax match typeScriptDocTags "@param" conceal cchar=⦿
syntax match typeScriptDocTags "@return" conceal cchar=↩

And the end result: