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dash.el Build Status

A modern list api for Emacs. No 'cl required.


It's available on marmalade and Melpa:

M-x package-install dash

Or you can just dump dash.el in your load path somewhere.

If you want the function combinators, then also:

M-x package-install dash-functional

Using in a package

Add this to the big comment block at the top:

;; Package-Requires: ((dash "2.13.0"))

To get function combinators:

;; Package-Requires: ((dash "2.13.0") (dash-functional "1.2.0") (emacs "24"))

Upcoming breaking change!

  • For backward compatibility reasons -zip return a cons-cell instead of a list with two elements when called on two lists. This is a clunky API, and in an upcoming 3.0 release of Dash it will always return a list. If you rely on the cons-cell return value, use -zip-pair instead.

Syntax highlighting of dash functions

Font lock of dash functions in emacs lisp buffers is now optional. Include this in your emacs settings to get syntax highlighting:

(eval-after-load 'dash '(dash-enable-font-lock))


All functions and constructs in the library are prefixed with a dash (-).

There are also anaphoric versions of functions where that makes sense, prefixed with two dashes instead of one.

While -map takes a function to map over the list, you can also use the anaphoric form with double dashes - which will then be executed with it exposed as the list item. Here's an example:

(-map (lambda (n) (* n n)) '(1 2 3 4)) ;; normal version

(--map (* it it) '(1 2 3 4)) ;; anaphoric version

of course the original can also be written like

(defun square (n) (* n n))

(-map 'square '(1 2 3 4))

which demonstrates the usefulness of both versions.

[[ function-list ]]

[[ function-docs ]]


Yes, please do. Pure functions in the list manipulation realm only, please. There's a suite of tests in dev/examples.el, so remember to add tests for your function, or I might break it later.

You'll find the repo at:

Run the tests with


Create the docs with


I highly recommend that you install these as a pre-commit hook, so that the tests are always running and the docs are always in sync:

cp .git/hooks/pre-commit

Oh, and don't edit directly, it is auto-generated. Change or examples-to-docs.el instead.


From 2.12 to 2.13

  • -let now supports &alist in destructuring.
  • Various performance improvements.
  • -zip will change in future so it always returns lists. Added -zip-pair for users who explicitly want the old behavior.
  • Added lexical binding pragma to dash.el, fixes #130 in Emacs 24+.
  • Added -select-column and -select-columns.
  • Fixed an issue with -map-last and --remove-last where they modified their inputs (#158).
  • Added -each-indexed and --each-indexed.
  • Added -take-last and -drop-last.
  • Added -doto macro.
  • -cut <> is now treated as a function, consistent with SRFI 26 (#185)

From 2.11 to 2.12

  • Add GNU ELPA support. (Phillip Lord)
  • Add -some->, -some->>, and -some--> macros. (Cam Saul)
  • -is-suffix? no longer destroys input list.
  • Faster hashtable implementation for -union.
  • Improvements to docstrings and examples

From 2.10 to 2.11

  • Lots of clean up wrt byte compilation, debug macros and tests

From 2.9 to 2.10

  • Add -let destructuring to -if-let and -when-let (Fredrik Bergroth)

From 2.8 to 2.9

  • Add -let, -let* and -lambda with destructuring
  • Add -tree-seq and -tree-map-nodes
  • Add -non-nil
  • Add -fix
  • Add -fixfn (dash-functional 1.2)
  • Add -copy (Wilfred Hughes)

From 2.7 to 2.8

  • Add -butlast

From 2.6 to 2.7

  • -zip now supports more than two lists (Steve Lamb)
  • Add -cycle , -pad , -annotate , -zip-fill (Steve Lamb)
  • Add -table, -table-flat (finite cartesian product)
  • Add -flatten-n
  • -slice now supports "step" argument
  • Add functional combinators -iteratefn, -prodfn
  • Add -replace, -splice, -splice-list which generalize -replace-at and -insert-at
  • Add -compose, -iteratefn and -prodfn (dash-functional 1.1)

From 2.5 to 2.6

  • Add -is-prefix-p, -is-suffix-p, -is-infix-p (Matus Goljer)
  • Add -iterate, -unfold (Matus Goljer)
  • Add -split-on, -split-when (Matus Goljer)
  • Add -find-last-index (Matus Goljer)
  • Add -list (Johan Andersson)

From 2.4 to 2.5

  • Add -same-items? (Johan Andersson)
  • A few bugfixes

From 2.3 to 2.4

  • Add -snoc (Matus Goljer)
  • Add -replace-at, -update-at, -remove-at, and -remove-at-indices (Matus Goljer)

From 2.2 to 2.3

  • Add tree operations (Matus Goljer)
  • Make font-lock optional

From 2.1 to 2.2

  • Add -compose (Christina Whyte)

From 2.0 to 2.1

  • Add indexing operations (Matus Goljer)

From 1.8 to 2.0

  • Split out dash-functional.el (Matus Goljer)
  • Add -andfn, -orfn, -not, -cut, -const, -flip and -on. (Matus Goljer)
  • Fix -min, -max, -min-by and -max-by (Matus Goljer)

From 1.7 to 1.8

  • Add -first-item and -last-item (Wilfred Hughes)

From 1.6 to 1.7

  • Add -rotate (Matus Goljer)

From 1.5 to 1.6

  • Add -min, -max, -min-by and -max-by (Johan Andersson)

From 1.4 to 1.5

  • Add -sum and -product (Johan Andersson)

From 1.3 to 1.4

  • Add -sort
  • Add -reduce-r (Matus Goljer)
  • Add -reduce-r-from (Matus Goljer)

From 1.2 to 1.3

  • Add -partition-in-steps
  • Add -partition-all-in-steps

From 1.1 to 1.2

  • Add -last (Matus Goljer)
  • Add -insert-at (Emanuel Evans)
  • Add -when-let and -if-let (Emanuel Evans)
  • Add -when-let* and -if-let* (Emanuel Evans)
  • Some bugfixes



New contributors are welcome. To ensure that dash.el can be distributed with ELPA or Emacs, we would request that all contributors assign copyright to the Free Software Foundation.


Copyright (C) 2012-2016 Free Software Foundation, Inc.

Authors: Magnar Sveen Keywords: lists

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see