Vim hotkey to run current file depending on the filetype

So, here’s the thing, you’re editing a file and you need to run it. And, since you are in vim, you might want to be clever and do something like :map <F5> :!ruby %<cr> on the fly. But, you can’t ever be clever enough in vim.

Autocmd is a feature of vim which allows to execute a command when an event occurs. In our context, we need vim to map a key to execute the current file in ruby if it is a ruby script. All we need is to add the following statement to .vimrc:

autocmd FileType ruby nmap <F5> :!ruby %<cr>

This means that when the “FileType” variable in vim will be set to ruby, the key F5 will be mapped to run current file with ruby. This is very convenient because usually that variable is set by syntax detectors.

Then, we can extend this and add new file types:

autocmd FileType ruby nmap <F5> :!ruby %<cr>
autocmd FileType coffee nmap <F5> :!coffee %<cr>

Neat, huh? Based on the file type, vim will execute the current file in the corresponding interpreter.

Taking it a bit further

Also, it would be nice to save the file each time you want to run it, and also measure the time it took to run. For that, you will need a function:

function RunWith (command)
  execute "w"
  execute "!clear;time " . a:command . " " . expand("%")
endfunction

autocmd FileType coffee nmap <F5> :call RunWith("coffee")<cr>
autocmd FileType ruby   nmap <F5> :call RunWith("ruby")<cr>

RunWith is a function which accepts the executable name which will be used to execute the current file. It will save the file before executing it, and will clear the console screen.

Pro tip: auto map a rspec run hotkey.

autocmd BufRead *_spec.rb nmap <F6> :w\|!clear && rspec % --format documentation --color<cr>

(each time a file with _spec.rb is loaded, the editor will map the F6 key to execute the rspec on the current file)

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