got millet working!

nvim/.config/nvim/lua/plugins/languages/sml.lua

@@ -0,0 +1,30 @@
+return {
+    {
+        'jez/vim-better-sml',
+        config = function()
+            vim.g.sml_smlnj_executable = 'smlnj'
+        end,
+        keys = {
+            {
+                '<leader>rs',
+                [[:SMLReplStart<CR>]],
+                desc = 'SML start repl'
+            },
+            {
+                '<leader>rc',
+                [[:SMLReplClear<CR>]],
+                desc = 'SML clear repl'
+            },
+            {
+                '<leader>rb',
+                [[:SMLReplBuild<CR>]],
+                desc = 'SML load current file/CM project in repl'
+            },
+            {
+                '<leader>ro',
+                [[:SMLReplOpen<CR>]],
+                desc = 'SML open current structure in repl'
+            },
+        }
+    }
+}

nvim/.config/nvim/lua/plugins/lsp.lua

@@ -18,6 +18,14 @@ return {
                 }
             })
 
+            lspconfig.millet.setup({
+                root_dir = function(fname)
+                    local util = require("lspconfig.util")
+                    return util.root_pattern(".cm", ".mlb")(fname)
+                        or util.path.dirname(fname)
+                end
+            })
+
             vim.api.nvim_create_autocmd('LspAttach', {
                 group = vim.api.nvim_create_augroup('UserLspConfig', {}),
                 callback = function(ev)

nvim/.config/nvim/lua/plugins/utils.lua

@@ -82,5 +82,18 @@ return {
             --     end
             -- }
         }
+    },
+    {
+        'stevearc/conform.nvim',
+        opts = {
+            formatters_by_ft = {
+                rust = { 'rustfmt', lsp_format = 'fallback' },
+                sml = { 'smlfmt' },
+            },
+            format_on_save = {
+                timeout_ms = 500,
+                lsp_format = 'fallback',
+            }
+        }
     }
 }