Vim

Flow’s editor integration is primarily via the Language Server Protocol. There are many vim LSP clients to choose from, such as ALE.

ALE

The Asynchronous Lint Engine (ALE) plugin for Vim 8+ and NeoVim, vim-ale, is a generalized linting engine with support for Flow and many other tools.

Installation

Follow the instructions in the ALE README.

Configure ALE to use the flow-language-server linter for JavaScript files:

" In ~/.vim/ftplugin/javascript.vim, or somewhere similar.

" Enables only Flow for JavaScript. See :ALEInfo for a list of other available
" linters. NOTE: the `flow` linter uses an old API; prefer `flow-language-server`.
let b:ale_linters = ['flow-language-server']

" Or in ~/.vim/vimrc:
let g:ale_linters = {
\   'javascript': ['flow-language-server'],
\}

coc.nvim-neovim

Coc is an intellisense engine for vim8 & neovim.

Setup

set nocompatible
filetype off

" install coc.nvim using Plug or preffered plugin manager
call plug#begin('~/.vim/plugged')
Plug 'neoclide/coc.nvim', {'branch': 'release'}
call plug#end()

filetype plugin indent on

" ======= coc settings
set updatetime=300
set shortmess+=c

" Use leader T to show documentation in preview window
nnoremap <leader>t :call <SID>show_documentation()<CR>


function! s:show_documentation()
  if (index(['vim','help'], &filetype) >= 0)
    execute 'h '.expand('&lt;cword&gt;')
  else
    call CocAction('doHover')
  endif
endfunction

" instead of having ~/.vim/coc-settings.json
let s:LSP_CONFIG = {
\  'flow': {
\    'command': exepath('flow'),
\    'args': ['lsp'],
\    'filetypes': ['javascript', 'javascriptreact'],
\    'initializationOptions': {},
\    'requireRootPattern': 1,
\    'settings': {},
\    'rootPatterns': ['.flowconfig']
\  }
\}

let s:languageservers = {}
for [lsp, config] in items(s:LSP_CONFIG)
  let s:not_empty_cmd = !empty(get(config, 'command'))
  if s:not_empty_cmd | let s:languageservers[lsp] = config | endif
endfor

if !empty(s:languageservers)
  call coc#config('languageserver', s:languageservers)
  endif

LanguageClient-neovim

Another way to add support for Flow in Vim is to use LanguageClient-neovim.

• Suports vim 8 and neovim
• Adds completions to omnifunc
• Checks JavaScript files for type errors on save
• Look up types under cursor

Requirements

• Requires Flow to be installed and available on your path.
• Requires projects containing JavaScript files to be initialised with flow init.
• Requires JavaScript files to be marked with /* @flow */ at the top.

Pathogen

cd ~/.vim/bundle
git clone git://github.com/autozimu/LanguageClient-neovim.git

NeoBundle

Add this to your ~/.vimrc

NeoBundleLazy 'autozimu/LanguageClient-neovim', {
    \ 'autoload': {
    \     'filetypes': 'javascript'
    \ }}

With Flow build step, using flow-bin

NeoBundleLazy 'autozimu/LanguageClient-neovim', {
    \ 'autoload': {
    \     'filetypes': 'javascript'
    \ },
    \ 'build': {
    \     'mac': 'npm install -g flow-bin',
    \     'unix': 'npm install -g flow-bin'
    \ }}

VimPlug

Plug 'autozimu/LanguageClient-neovim', {
    \ 'branch': 'next',
    \ 'do': 'bash install.sh && npm install -g flow-bin',
    \ }

Setup

let g:LanguageClient_rootMarkers = {
\   'javascript': ['.flowconfig', 'package.json']
\ }
let g:LanguageClient_serverCommands={
\   'javascript': ['flow', 'lsp'],
\   'javascript.jsx': ['flow', 'lsp']
\}

" check the type under cursor w/ leader T
nnoremap <leader>t :call LanguageClient_textDocument_hover()<CR>
nnoremap <leader>y :call LanguageClient_textDocument_definition()<CR>