Implement showing help via lsp hover not via keywordprg (Credit: SirZenith)

README.md

@@ -20,7 +20,7 @@
 - Neovim version >= 0.5
 - A [nu](https://github.com/nushell/nushell/releases) binary in your path
 - [nvim-treesitter](https://github.com/nvim-treesitter/nvim-treesitter/blob/master/README.md#quickstart) installed
-- [null-ls.nvim](https://github.com/jose-elias-alvarez/null-ls.nvim) if nu-command names shall be suggested
+- Optionally [null-ls.nvim](https://github.com/jose-elias-alvarez/null-ls.nvim) to enable lsp features like hover (aka help) or command completion
 
 # Installation
 
@@ -50,3 +50,12 @@ require'nu'.setup{
     all_cmd_names = [[nu -c 'help commands | get name | str join "\n"']]
 }
 ```
+
+To enable hover (aka help) `vim.lsp.buf.hover` must be mapped. You can do so for example in your `ftplugin/nu.lua`
+```lua
+vim.keymap.set('n', 'K', vim.lsp.buf.hover, { buffer = true })
+```
+
+## Known issues (PR's welcome)
+
+* Calling `vim.lsp.buf.hover` on a subcommand does not show the help for the subcommand

ftplugin/nu.lua

@@ -1,4 +1,3 @@
 require 'nu'._init() -- lazy initialise
 
 vim.opt_local.commentstring = "#%s"
-vim.opt_local.keywordprg = ":ShowDocumentation"

lua/nu/lsp.lua

@@ -1,4 +1,6 @@
 local null_ls = require("null-ls")
+local null_ls_methods = require("null-ls.methods")
+local null_ls_helpers = require("null-ls.helpers")
 local log = require("nu.log")
 local vim = vim
 
@@ -114,6 +116,38 @@ local nu_lsp = {
     },
 }
 
-null_ls.register(nu_lsp)
+local nu_hover = null_ls_helpers.make_builtin {
+    name = "nu_hover",
+    factory = null_ls_helpers.generator_factory,
+    generator_opts = {
+        command = "nu",
+        format = "raw",
+        args = function(params)
+            local cword = vim.fn.expand("<cword>")
+            local nu_cmd =
+            'if (help commands | where name == "' ..
+                cword ..
+                '" | length ) > 0 {help ' ..
+                cword .. ' | str replace -a `\\u001B\\[[0-9;]*m` ``} else {man ' .. cword .. '}'
+            log.trace("Executing", nu_cmd)
+            return { "-c", nu_cmd }
+        end,
+        on_output = function(params, done)
+            if params.err ~= nil then
+                done({ params.err })
+            else
+                done({ params.output })
+            end
+        end
+    },
+    filetypes = { "nu" },
+    method = null_ls_methods.internal.HOVER,
+    meta = {
+        url = "help",
+        description = "nushell help output"
+    }
+}
+
+null_ls.register({ nu_hover, nu_lsp })
 
 return M

plugin/nu.vim

@@ -1,11 +1 @@
-function! s:ShowDocumentation(word)
-    let nu_help = system('nu -c "help '. a:word .'"')
-    if v:shell_error == 0
-        echo nu_help
-    else
-        execute '!man '. a:word
-    endif
-endfunction
-command! -nargs=1 ShowDocumentation :call s:ShowDocumentation(<f-args>)
-
 lua require('nu.tree_sitter_config')