Have DAPs work in way that allows being shadowed by nix-shell/direnv.

jrpotter/default.nix

@@ -1,11 +1,23 @@
-{ pkgs, ... }:
+{ config, pkgs, lib, ... }:
 {
+  options.home.extraPythonPackages = lib.mkOption {
+    type = lib.types.listOf lib.types.string;
+    example = ''
+      [ debugpy mccabe ]
+    '';
+    description = lib.mdDoc ''
+      Extra Python packages that should be linked to the topmost Python
+      interpreter.
+    '';
+  };
+
   imports = [
     ./git.nix
     ./neovim
     ./wezterm
   ];
 
+  config = {
     home = {
       username = "jrpotter";
       homeDirectory = "/home/jrpotter";
@@ -13,11 +25,13 @@
       packages = with pkgs; [
         anki-bin
         bitwarden
+        clang
         elan
         firefox
         gnumake
         mullvad-vpn
-      python3
+        (python3.withPackages
+          (ps: builtins.map (s: ps.${s}) config.home.extraPythonPackages))
         unzip
         wezterm
         zotero
@@ -41,4 +55,5 @@
     # See the Home Manager release notes for a list of state
     # version changes in each release.
     home.stateVersion = "23.05";
+  };
 }

jrpotter/neovim/default.nix

@@ -32,6 +32,7 @@ let
     plugin = (pkgs.vimPlugins.nvim-treesitter.withPlugins (
       ps: with ps; [
         bash
+        c
         elixir
         lua
         nix
@@ -67,8 +68,19 @@ in
     };
   };
 
+  # Notice that within our imports we use `home.packages` instead of
+  # `extraPackages`. The latter is preferable but comes with `$PATH`-related
+  # problems.
+  #
+  # Specifically, Home Manager appends paths specifed in `extraPackages` to the
+  # end of `$PATH` meaning any already defined instance of some package will be
+  # used instead. Prepending is not an option either since that would break
+  # environments like those produced by `direnv` or `nix-shell`.
+  #
+  # https://github.com/nix-community/home-manager/pull/1756
   imports = [
     ./lang/bash.nix
+    ./lang/c.nix
     ./lang/elixir.nix
     ./lang/lean.nix
     ./lang/lua.nix

jrpotter/neovim/lang/bash.nix

@@ -1,13 +1,13 @@
 { pkgs, ... }:
 {
+  home.packages = with pkgs; [
+    nodePackages.bash-language-server
+    shellcheck
+  ];
+
   programs.neovim = {
     nvim-lspconfig = ''
       require('init.lsp').setup(require('lspconfig').bashls) {}
     '';
-
-    extraPackages = with pkgs; [
-      nodePackages.bash-language-server
-      shellcheck
-    ];
   };
 }

jrpotter/neovim/lang/c.nix

@@ -0,0 +1,23 @@
+{ pkgs, ... }:
+{
+  home.packages = with pkgs; [
+    clang-tools
+    vscode-extensions.vadimcn.vscode-lldb
+  ];
+
+  programs.neovim = {
+    nvim-dap = ''
+      require('init.c').nvim_dap({
+        command = '${pkgs.vscode-extensions.vadimcn.vscode-lldb}/share/vscode/extensions/vadimcn.vscode-lldb/adapter/codelldb'
+      })
+    '';
+
+    nvim-lspconfig = ''
+      require('init.c').nvim_lspconfig()
+    '';
+  };
+
+  xdg.configFile."nvim/after/ftplugin/c.lua".text = ''
+    require('init.dap').buffer_map()
+  '';
+}

jrpotter/neovim/lang/elixir.nix

@@ -1,14 +1,14 @@
 { pkgs, ... }:
 {
+  home.packages = with pkgs; [
+    elixir-ls
+  ];
+
   programs.neovim = {
     nvim-lspconfig = ''
       require('init.lsp').setup(require('lspconfig').elixirls) {
         cmd = { 'elixir-ls' },
       }
     '';
-
-    extraPackages = with pkgs; [
-      elixir-ls
-    ];
   };
 }

jrpotter/neovim/lang/lua.nix

@@ -1,10 +1,12 @@
 { pkgs, ... }:
 {
+  home.packages = with pkgs;[
+    lua-language-server
+  ];
+
   programs.neovim = {
     nvim-lspconfig = ''
       require('init.lua').nvim_lspconfig()
     '';
-
-    extraPackages = [ pkgs.lua-language-server ];
   };
 }

jrpotter/neovim/lang/nix.nix

@@ -1,10 +1,12 @@
 { pkgs, ... }:
 {
+  home.packages = with pkgs; [
+    nil
+  ];
+
   programs.neovim = {
     nvim-lspconfig = ''
       require('init.lsp').setup(require('lspconfig').nil_ls) {}
     '';
-
-    extraPackages = [ pkgs.nil ];
   };
 }

jrpotter/neovim/lang/python.nix

@@ -1,15 +1,14 @@
-{ pkgs, ... }:
-let
-  venv = pkgs.python3.withPackages (ps: with ps; [
-    debugpy
-    mccabe
-    pycodestyle
-    pyflakes
-    python-lsp-server
-    python-lsp-black
-  ]);
-in
+{ ... }:
 {
+  home.extraPythonPackages = [
+    "debugpy"
+    "mccabe"
+    "pycodestyle"
+    "pyflakes"
+    "python-lsp-server"
+    "python-lsp-black"
+  ];
+
   programs.neovim = {
     nvim-dap = ''
       require('init.python').nvim_dap()
@@ -18,8 +17,6 @@ in
     nvim-lspconfig = ''
       require('init.python').nvim_lspconfig()
     '';
-
-    extraPackages = [ venv ];
   };
 
   xdg.configFile."nvim/after/ftplugin/python.lua".text = ''

jrpotter/neovim/lang/typescript.nix

@@ -1,13 +1,13 @@
 { pkgs, ... }:
 {
+  home.packages = with pkgs; [
+    nodePackages.typescript-language-server
+  ];
+
   programs.neovim = {
     nvim-lspconfig = ''
       require('init.lsp').setup(require('lspconfig').tsserver) {}
     '';
-
-    extraPackages = with pkgs; [
-      nodePackages.typescript-language-server
-    ];
   };
 }
 

jrpotter/neovim/lua/init/c.lua

@@ -0,0 +1,32 @@
+local M = {}
+
+function M.nvim_dap(options)
+  local dap = require('dap')
+  local key = 'codelldb'
+
+  dap.adapters[key] = {
+    type = 'server',
+    port = '${port}',
+    executable = {
+      command = options.command,
+      args = {'--port', '${port}'},
+    },
+  }
+
+  dap.configurations.c = dap.configurations.c or {}
+  table.insert(dap.configurations.c, {
+    name = 'Launch Executable',
+    type = key,
+    request = 'launch',
+    program = function()
+      return vim.fn.input('Path to executable: ', vim.fn.getcwd() .. '/', 'file')
+    end,
+    cwd = '${workspaceFolder}',
+  })
+end
+
+function M.nvim_lspconfig()
+  require('init.lsp').setup(require('lspconfig').clangd) {}
+end
+
+return M

jrpotter/neovim/lua/init/python.lua

@@ -2,23 +2,21 @@ local M = {}
 
 function M.nvim_dap()
   local dap = require('dap')
+  local key = 'debugpy'
 
-  dap.adapters.python = function(callback, config)
-    callback({
-      name = 'debugpy',
+  dap.adapters[key] = {
     type = 'executable',
     command = 'python3',
     args = { '-m', 'debugpy.adapter' },
     options = {
       source_filetype = 'python',
     },
-    })
-  end
+  }
 
   dap.configurations.python = dap.configurations.python or {}
   table.insert(dap.configurations.python, {
-    name = 'Launch',
-    type = 'python',
+    name = 'Launch File',
+    type = key,
     request = 'launch',
     program = '${file}',
     cwd = '${workspaceFolder}',