nvim: after/ftplugin/haskell: Lint on save

Now that we use static-ls as Haskell LSP which does not
have hlint support for diagnostics yet, lint on save to
get hlint diagnostics.

nvim/.config/nvim/after/ftplugin/haskell.lua

@@ -4,3 +4,10 @@ local hls_config = lsp_utils.hls_config()
 vim.lsp.start(hls_config)
 
 vim.bo.makeprg = 'cabal build --write-ghc-environment-files=always all'
+
+vim.api.nvim_create_autocmd({ "BufWritePost" }, {
+  buffer   = 0,
+  callback = function()
+    require("lint").try_lint()
+  end,
+})