q-mode

q-mode is a major mode for editing q (the language written by Kx Systems) in Emacs.

Some of its major features include:

• syntax highlighting (font-lock-mode),
• syntax checking (flymake-mode),
• interaction with inferior q[con] instance (comint-mode),
• inline eval results next to the code that produced them (q-inline-mode),
• native Emacs qcon replacement supporting TLS (q-con),
• secure password retrieval (auth-source),
• named remote connections (q-connections),
• incremental, project-wide indexing (imenu, xref),
• completion at point (CAPF),
• signature help (eldoc),
• current function in the mode line (which-function-mode),
• code folding (hideshow).

To load q-mode on-demand, instead of at startup, add this to your initialization file

(autoload 'q-mode "q-mode")

Then add the following to your initialization file to open all .k and .q files with q-mode as major mode automatically:

(add-to-list 'auto-mode-alist '("\\.[kq]\\'" . q-mode))

If you load ess-mode, it will attempt to associate the .q extension with S-mode. To stop this, add the following lines to your initialization file.

(defun remove-ess-q-extn ()
 (when (assoc "\\.[qsS]\\'" auto-mode-alist)
  (setq auto-mode-alist
        (remassoc "\\.[qsS]\\'" auto-mode-alist))))
(add-hook 'ess-mode-hook 'remove-ess-q-extn)
(add-hook 'inferior-ess-mode-hook 'remove-ess-q-extn)

Use M-x q to start an inferior q shell. Or use M-x q-qcon to create an inferior qcon shell to communicate with an existing q process. Both can be prefixed with the universal-argument C-u to customize the arguments used to start the processes.

M-x q-con talks to an existing q process the same way q-qcon does, but without executing an external qcon binary: Emacs opens the TCP connection itself. This matters for the password - qcon receives it as a literal command-line argument, so it's visible to anyone on the machine running ps; q-con resolves it from auth-source only for the instant it takes to write it to the socket, and it never becomes a command-line argument at all. q-con also supports TLS: prefix a host with tcps:// - in q-connection-host, a q-connections entry, or typed ad-hoc at the prompt - to connect over TLS instead of plain tcp.

When prompted this way, q-qcon and q-con both offer named connections from q-connections as completion candidates, alongside the option of typing an ad-hoc "host:port[:user]" string. Each entry in q-connections is a (NAME HOST PORT USER) list, letting you refer to a remote q server by a short name instead of retyping its host/port/user every time. In every case, the password itself is never typed or stored in q-connections - it's always resolved from auth-source. .netrc/.authinfo is the common case, but auth-source is backend-agnostic: anything registered as an auth-source-backend (e.g. the system Secret Service/macOS Keychain via auth-source-pass or secrets.el, or a custom backend you write yourself) is consulted the same way, so the password need not live in a plaintext file at all.

The first q[con] session opened becomes the activated buffer. To open a new session and send code to the new buffer, it must be activated. Switch to the desired buffer and type C-c M-RET to activate it.

Displaying tables with many columns will wrap around the buffer - making the data hard to read. You can use the toggle-truncate-lines function to prevent the wrapping. You can then scroll left and right in the buffer to see all the columns.

The following commands are available to interact with an inferior q[con] process/buffer. C-c C-j (as well as C-c C-l and C-M-x) sends a single line, C-c C-f sends the surrounding function, C-c C-s sends the symbol at point, C-c C-r sends the selected region and C-c C-b sends the whole buffer. If prefixed with C-u C-u, or pressing C-c M-j C-c M-f C-c M-s C-c M-r respectively, will also switch point to the active q process buffer for direct interaction. Evaluations performed in non-root namespaces are pre/post-fixed with a command to change directory.

If the source file exists on the same machine as the q process, C-c M-l can be used to load the file associated with the active buffer.

M-x q-inline-mode toggles showing eval results as an overlay next to the code that produced them, in addition to the usual q[con] buffer output. C-c C-. pops up the full, untruncated reply for the result at point (useful for tables, which are shown truncated to their first line inline); C-c C-k clears the result at point, and C-u C-c C-k clears every result in the buffer. Editing the code a result is attached to clears that result automatically. The q-inline-duration variable controls how long a result stays visible: nil (the default) leaves it until the code is edited or explicitly cleared, a number of seconds auto-clears it after that long, and the symbol command clears it as soon as any command runs.

C-c C-g triggers a manual rescan of the project, re-scanning only files whose mtime has changed. Prefix with C-u to force all files to be re-scanned regardless of mtime, which is useful after a branch switch where file timestamps may be preserved.

Quick access to variable and function definitions can be obtained using the imenu binding M-g i. Completion is available via completion-at-point (usually M-TAB). Candidates are annotated with their kind (, , , or ). Eldoc displays signatures while you type, and xref provides M-. for definitions, M-? for references, and C-M-. for apropos search across all known identifiers in the project.

Code folding is available via hs-minor-mode. Once enabled, use the standard hideshow bindings to fold and unfold {} blocks.

which-function-mode is supported and will display the name of the enclosing function in the mode line as you move point. Enable it globally with (which-function-mode 1) in your initialization file, or per-buffer with M-x which-function-mode.

M-x customize-group can be used to customize the q group. Specifically, the q-program and q-qcon-program variables can be changed depending on your environment. The q-rescan-idle-delay variable controls how long to wait after a save before rescanning; it debounces rapid saves and defers the check for out-of-band disk changes such as those made by git pull.

Q-mode indents each level based on q-indent-step. To indent code based on {}-, ()-, and []-groups instead of equal width tabs, you can set this value to nil.

Flymake behavior is controlled by q-flymake-on-save. When non-nil, checks run only after saving. When nil (default), checks run for unsaved buffers by evaluating a temporary file containing current buffer contents.