Awesome

vim-ungrammar

Vim-ungrammar is a plugin for Neovim and Vim for the Ungrammar filetype which provides:

Filetype detection.
ftplugin setting adjustments.
- Use let g:ungrammar_formatting = v:false to turn it off.
Syntax files.

Here is a preview of the syntax highlighting, using nvim-highlite as a theme:

preview

This plugin defines the following syntax groups:

Group Name	Description	Example
`ungramAlternation`	An alternation on a rule.	`\|`
`ungramConditionalGroup`	A group which is a conditional.	`(Foo\|Bar)?`
`ungramConditionalString`	A conditional `ungramString`.	`'for'?`
`ungramConditional`	A conditional (1-or-0).	`?`
`ungramLabel`	A label for a token or string.	`scope:'local'`
`ungramOperator`	An operator.	`=`
`ungramOr`	Alternative for a given position.	`Foo\|Bar`
`ungramQuote`	A quote for a string or token.	`'`
`ungramRepeatGroup`	A group which is repeated.	`(Foo\|Bar)*`
`ungramRepeatString`	A repeated `ungramString`.	`'for'*`
`ungramRepeat`	0 or more repetitions.	`*`
`ungramRule`	A rule for a grammar.	`Foo`
`ungramString`	A specific string of characters.	`'for'`
`ungramToken`	A token.	`'identifier_var'`

You can use this plugin seamlessly with plasticboy/vim-markdown provided that the following is part of your init.vim configuration:

let g:vim_markdown_fenced_languages = ['ungram=ungrammar']

Then, you can create codeblocks in markdown and it will use the syntax file from this plugin:

	```ungram
	 Foo = 'A' | 'B'

Learn Vimscript The Hard Way got me started.
plasticboy wrote a fantastic markdown plugin with syntax highlighting for fenced code blocks.
rust-analyzer/ungrammar created the syntax and initial implementation.
tbastos/vim-lua open sourced a clear example of syntax files.