extra: nvim: Add haskell-tools.nvim plugins

Signed-off-by: Christoph Heiss <christoph@c8h4.io>

extra/nvim/lua/plugins.lua

@@ -286,6 +286,31 @@ require('lazy').setup({
           })
         end,
       },
+      {
+        'mrcjkb/haskell-tools.nvim',
+        dependencies = { 'nvim-lua/plenary.nvim' },
+        opts = {
+          hls = {
+            settings = {
+              haskell = {
+                formattingProvider = 'stylish-haskell',
+              },
+            },
+            on_attach = function(client, bufnr)
+              local opts = vim.tbl_extend('keep', def_opts, { buffer = bufnr })
+              -- haskell-language-server relies heavily on codeLenses,
+              -- so auto-refresh (see advanced configuration) is enabled by default
+              vim.keymap.set('n', '<leader>ll', vim.lsp.codelens.run, opts)
+              vim.keymap.set(
+                'n',
+                '<leader>lh',
+                ht.hoogle.hoogle_signature,
+                opts
+              )
+            end,
+          },
+        },
+      },
     },
     config = function()
       local cmp = require('cmp')