Lambda-line is a custom status-line (or “mode-line) for Emacs. It is configurable for use either as a header-line or as a footer-line.

The status-line has the structure:

[ status name (primary) tertiary secondary ]

Information displayed depends on major mode. Not all segments display in every mode.

To achieve the above coloration of the status-line see lambda-themes.

Installation

Lambda-line is not yet on MELPA. In the meantime to use this package you’ll have to clone or otherwise download the repo and put it into your load path. Here’s a basic way of setting it up using use-package and straight.

(use-package lambda-line
  :straight (:type git :host github :repo "lambda-emacs/lambda-line") 
  :custom
  (lambda-line-icon-time t) ;; requires all-the-icons
  (lambda-line-position 'top) ;; Set position of status-line 
  (lambda-line-abbrev t) ;; abbreviate major modes
  (lambda-line-hspace "  ")  ;; add some cushion
  (lambda-line-prefix t) ;; use a prefix symbol
  (lambda-line-prefix-padding nil) ;; no extra space for prefix 
  (lambda-line-status-invert nil)  ;; no invert colors
  (lambda-line-gui-ro-symbol  " ⨂") ;; symbols
  (lambda-line-gui-mod-symbol " ⬤") 
  (lambda-line-gui-rw-symbol  " ◯") 
  (lambda-line-space-top +.50)  ;; padding on top and bottom of line
  (lambda-line-space-bottom -.50)
  (lambda-line-symbol-position 0.1) ;; adjust the vertical placement of symbol
  :config
  ;; activate lambda-line 
  (lambda-line-mode) 
  ;; set divider line in footer
  (when (eq lambda-line-position 'top)
    (setq-default mode-line-format (list "%_"))
    (setq mode-line-format (list "%_"))))

Options

Lambda-line has a lot of different options for customization. Please see M-x customize-group lambda-line for full details.

• Set lambda-line-position to header (top) or footer (bottom).
• Use a prefix status icon in the status-line with lambda-line-prefix t.
• Customize the various prefix status symbols in both GUI and TTY with lambda-line-GUI/TTY-RO/RW/MD-symbol.
  • NOTE: If you use symbols you should make sure you are using a font that will display them properly. Here is one reliable way, using Symbola font:

    (use-package fontset
      :straight (:type built-in) ;; only include this if you use straight
      :config
      ;; Use symbola for proper unicode
      (when (member "Symbola" (font-family-list))
        (set-fontset-font
         t 'symbol "Symbola" nil)))
            

• Abbreviate major modes with lambda-line-abbrev.
• Show current time (via dynamic svg icon); note that time info is only shown `display-time-mode’ is non-nil.
• Show both vc project and branch in the modeline
• Show the diff in the status-line with lambda-line-git-diff-mode-line.
• Set the symbol for vc project buffers with lambda-line-vc-symbol.
• Set a visual bell with lambda-line-visual-bell.
• Set char length for truncating information using lambda-line-truncate-value.
• Control the right margin padding with lambda-line-hspace.
• Set the top and bottom padding of the status-line with lambda-line-space-top. and lambda-line-space-bottom.
• Set the position of the prefix status symbol with lambda-line-symbol-position.
• Show flycheck/flymake report in status-line with lambda-line-syntax.
  • If you use flymake, you might want to configure the status-line display with the following, which provides a minimalist display:

(customize-set-variable 'flymake-mode-line-counter-format '("" flymake-mode-line-error-counter flymake-mode-line-warning-counter flymake-mode-line-note-counter ""))
(customize-set-variable 'flymake-mode-line-format '(" " flymake-mode-line-exception flymake-mode-line-counters))

• Set the modes in which the status-line is formatted with lambda-line-mode-formats.
• Set the default display function for the status-line with lambda-line-default-mode-format. This is set to lambda-line-default-mode but can be customized to any function the user wishes.

Lambda-line also sets a variety of faces that can be individually customized.

Acknowledgments

• The basic structure of the status line is heavily indebted to Rougier’s work on nano-modeline.
• My bespoke-modeline was my first attempt to create a custom mode-line and the original basis for much of the current code.
• The idea for the flycheck/flymake segment function is originally from mood-line.