REPL history browser

You can browse your REPL input history with the command M-x cider-repl-history. This command is bound to C-c M-p in cider-repl-mode buffers and is also available via the history shortcut.

The history is displayed in reverse order, with the most recent input at the top of the buffer, and the oldest input at the bottom. You can scroll through the history, and when you find the history item you were looking for, you can insert it from the history buffer into your REPL buffer.

History Browser

Mode

The history buffer has its own major mode, cider-repl-history-mode. This is derived from clojure-mode, so you get fontification in the history buffer. This mode supports the expected defcustom hook variable, cider-repl-history-hook.

Insertion

Where you use the history buffer to insert text into the REPL buffer, the exact behavior depends on the location of the cursor in the buffer prior to the insertion.

Typically, when you’re actively using the REPL, your cursor will be at the end of the REPL buffer (point-max). In this case, the text is inserted at the end of the buffer and the point advances to the end of the inserted text (as if point was pushed by along by the text as it was inserted).

In the unusual case where you invoke the history browser when your cursor is not at the end of the REPL buffer, the inserted text will still be inserted at the end of the buffer (point-max), but the point is not modified.

CIDER inserts the text without a final newline, allowing you to edit it. When you are ready, hit Return to have it evaluated by the REPL.

Quitting

If you select an input, the text will be inserted into the REPL buffer and the history buffer will automatically quit. If you decide you want to quit without inserting any text at all, you can explicitly quit by running cider-repl-history-quit (see keyboard shortcuts). Because of the initialization and cleanup that is done when using the history buffer, it is better to quit properly rather than just switch away from the history buffer.

When you quit the history buffer, CIDER can restore the buffer and window configuration in a few different ways. The behavior is controlled by cider-repl-history-quit-action, which can be assigned one of several values:

  • quit-window restores the window configuration to what it was before. This is the default.

  • delete-and-restore restores the window configuration to what it was before, and kills the cider-repl-history buffer.

  • kill-and-delete-window kills the cider-repl-history buffer, and deletes the window.

  • bury-buffer simply buries the cider-repl-history buffer, but keeps the window.

  • bury-and-delete-window buries the buffer, and deletes the window if there is more than one window.

  • any other value is interpreted as the name of a function to call

Filtering

By invoking cider-repl-history-occur from the history buffer, you will be prompted for a regular expression. The history buffer will be filtered to only those inputs that match the regexp.

Preview and Highlight

When cider-repl-history-show-preview is non-nil, CIDER displays an [overlay] (https://www.gnu.org/software/emacs/manual/html_node/elisp/Overlays.html) of the currently selected history entry, in the REPL buffer.

If you do not properly quit from browsing the history (i.e., if you just C-x b away from the buffer), you may be left with an unwanted overlay in your REPL buffer. If this happens, you can clean it up with M-x cider-repl-history-clear-preview.

By default, cider-repl-history-show-preview is nil (disabled).

There is a related feature to highlight the entry once it is actually inserted into the REPL buffer, controlled by the variable cider-repl-history-highlight-inserted-item, which can be set to the following values:

  • solid highlights the inserted text for a fixed period of time.

  • pulse causes the highlighting to fade out gradually.

  • t selects the default highlighting style, which is currently pulse.

  • nil disables highlighting. This is the default value for cider-repl-history-highlight-inserted-item.

When cider-repl-history-highlight-inserted-item is non-nil, you can customize the face used for the inserted text with the variable cider-repl-history-inserted-item-face.

Additional Customization

There are quite a few customizations available, in addition to the ones already mentioned.

  • cider-repl-history-display-duplicates - when set to nil, will not display any duplicate entries in the history buffer. Default is t.

  • cider-repl-history-display-duplicate-highest - when not displaying duplicates, this controls where in the history the one instance of the duplicated text is displayed. When t, it displays the entry in the highest position applicable; when nil, it displays it in the lowest position.

  • cider-repl-history-display-style - the history entries will often be more than one line. The package gives you two options for displaying the entries:

    • separated - a separator string is inserted between entries; entries may span multiple lines. This is the default.

    • one-line - any newlines are replaced with literal \n strings, and therefore no separator is necessary. Each \n becomes a proper newline when the text is inserted into the REPL.

  • cider-repl-history-separator - when cider-repl-history-display-style is separated, this gives the text to use as the separator. The default is a series of ten semicolons, which is, of course, a comment in Clojure. The separator could be anything, but it may screw up the fontification if you make it something weird.

  • cider-repl-history-separator-face - specifies the face for the separator.

  • cider-repl-history-maximum-display-length - when nil (the default), all history items are displayed in full. If you prefer to have long items abbreviated, you can set this variable to an integer, and each item will be limited to that many characters. (This variable does not affect the number of items displayed, only the maximum length of each item.)

  • cider-repl-history-recenter - when non-nil, always keep the current entry at the top of the history window. Default is nil.

  • cider-repl-history-resize-window - whether to resize the history window to fit its contents. Value is either t, meaning yes, or a cons pair of integers, (MAXIMUM . MINIMUM) for the size of the window. MAXIMUM defaults to the window size chosen by pop-to-buffer; MINIMUM defaults to window-min-height.

  • cider-repl-history-highlight-current-entry - if non-nil, highlight the currently selected entry in the history buffer. Default is nil.

  • cider-repl-history-current-entry-face - specifies the face for the history-entry highlight.

  • cider-repl-history-text-properties - when set to t, maintains Emacs text properties on the entry. Default is nil.

Key Bindings

There are a number of important keybindings in history buffers.

Keyboard shortcut Description

n

Go to next (lower, older) item in the history.

p

Go to previous (higher, more recent) item in the history.

RET or SPC

Insert history item (at point) at the end of the REPL buffer, and quit.

l (lower-case L)

Filter the command history (see Filtering, above).

s

Regexp search forward.

r

Regexp search backward.

q

Quit (and take quit action).

U

Undo in the REPL buffer.