lsp: show function signature, use conform.nvim for formatting code.

config/lsp/conform.nix

@@ -0,0 +1,37 @@
+{ helpers, pkgs, ... }: {
+  plugins.conform-nvim = {
+    enable = true;
+    formatAfterSave = ''
+      {
+        format_after_save = {
+          lsp_format = "fallback",
+        },
+      }
+    '';
+    formattersByFt = {
+      python = [ "black" ];
+      c = [ "clang-format" ];
+      cpp = [ "clang-format" ];
+      cmake = [ "cmake_format" ];
+      nix = [ "nixfmt" ];
+      # Standalone scalafmt is too slow, so we use it as a fallback
+      scala = helpers.mkRaw ''
+        { scalafmt, lsp_format = "prefer" }
+      '';
+      toml = [ "taplo" ];
+      yaml = [ "yq" ];
+      json = [ "jq" ];
+    };
+  };
+
+  extraPackages = with pkgs; [
+    black
+    clang-tools
+    cmake-format
+    jq
+    nixfmt-rfc-style
+    scalafmt
+    taplo
+    yq
+  ];
+}

config/lsp/default.nix

@@ -1,5 +1,6 @@
 {
   imports = [
+    ./conform.nix
     ./lsp.nix
     ./lsp-format.nix
     ./lspkind.nix

config/lsp/lsp.nix

@@ -1,4 +1,4 @@
-{ helpers, ... }:
+{ pkgs, helpers, ... }:
 
 {
   plugins.lsp = {
@@ -69,6 +69,14 @@
         };
       };
     };
+    onAttach = ''
+      require("lsp_signature").on_attach({
+        bind = true,
+        handler_opts = {
+          border = "rounded"
+        };
+      }, bufnr)    
+    '';
   };
 
   keymaps = [
@@ -85,4 +93,20 @@
       };
     }
   ];
+
+  extraConfigLua = ''
+    require("lspconfig").asm_lsp.setup {
+      filetypes = { "asm", "s", "S" }
+    }
+    require("lspconfig").verible.setup { }
+  '';
+
+  extraPlugins = with pkgs.vimPlugins; [
+    lsp_signature-nvim
+  ];
+
+  extraPackages = with pkgs; [
+    asm-lsp
+    verible
+  ];
 }

config/lsp/nvim-metals.nix

@@ -8,12 +8,28 @@
 
   extraPackages = [
     pkgs.metals
+    pkgs.scalafmt
   ];
 
   autoGroups.nvim_metals_group = {
     clear = true;
   };
 
+  extraConfigLua = ''
+    metals_config = require("metals").bare_config()
+    metals_config.init_options.statusBarProvider = "off"
+    metals_config.settings = {
+      showInferredType = true,
+      showImplicitArguments = false,
+      showImplicitConversionsAndClasses = false,
+      metalsBinaryPath = "${pkgs.lib.getExe pkgs.metals}",
+      excludedPackages = { "akka.actor.typed.javadsl", "com.github.swagger.akka.javadsl" },
+      useGlobalExecutable = true,
+      verboseCompilation = true
+    }
+    metals_config.capabilities = require("cmp_nvim_lsp").default_capabilities()
+  '';
+
   autoCmd = [
     {
       event = "FileType";
@@ -21,18 +37,10 @@
       desc = "Initialize nvim-metals";
       callback = helpers.mkRaw ''
         function()
-          metals_config = require("metals").bare_config()
-          metals_config.init_options.statusBarProvider = "off"
-          metals_config.settings = {
-            showInferredType = true,
-            showImplicitArguments = false,
-            showImplicitConversionsAndClasses = false,
-            metalsBinaryPath = "${pkgs.lib.getExe pkgs.metals}",
-            useGlobalExecutable = true
-          }
           require("metals").initialize_or_attach(metals_config)
         end
       '';
+      pattern = [ "scala" "sbt" ];
     }
   ];