Vim as a Haskell IDE
There is a wide range of tools and corresponding VIM plugins that provide IDE-like features for Haskell development: haskell-ide-engine (implements the Language Server Protocol, thus needs a VIM LSP client), Intero, Dante, Codex, hdevtools and more. A less feature-rich but stable solution is to have ghcid running next to the editor window as described in 
- coc.nvim Intellisense engine for Vim8 & Neovim, full language server protocol support as VSCode. Follow haskell-ide-engine instructions to add support for completion, linting, formatting, go to definition, etc.
- Hindent Haskell pretty printer
- stylish-haskell Haskell code prettifier
- Ale (Asynchronous Linting Engine)
ALE (Asynchronous Lint Engine) is a plugin for providing linting (checking syntax and semantics) in NeoVim 0.2.0+ and Vim 8 while you edit your text files, and acts as a Vim Language Server Protocol client.
Comes with linters cabal_ghc, ghc, ghc_mod, hdevtools, hie, hlint, stack_build, stack_ghc
- Hdevtools taken from the github page:
hdevtools is a command line program powered by the GHC API, that provides services for Haskell development. hdevtools works by running a persistent process in the background, so that your Haskell modules remain in memory, instead of having to reload everything each time you change only one file. This is just like :reload in GHCi - with hdevtools you get the speed of GHCi as well as tight integration with your editor.
This is the Vim plugin that integrates Vim with hdevtools.