Functions

This chapter contains reference documentation for the Dash API (Application Programming Interface). The names of all public functions defined in the library are prefixed with a dash character (‘-’).

The library also provides anaphoric macro versions of functions where that makes sense. The names of these macros are prefixed with two dashes (‘--’) instead of one.

For instance, while the function -map applies a function to each element of a list, its anaphoric counterpart --map evaluates a form with the local variable it temporarily bound to the current list element instead.

;; Normal version.
(-map (lambda (n) (* n n)) '(1 2 3 4))
    ⇒ (1 4 9 16)

;; Anaphoric version.
(--map (* it it) '(1 2 3 4))
    ⇒ (1 4 9 16)

The normal version can, of course, also be written as in the following example, which demonstrates the utility of both versions.

(defun my-square (n)
  "Return N multiplied by itself."
  (* n n))

(-map #'my-square '(1 2 3 4))
    ⇒ (1 4 9 16)

• Maps
• Sublist selection
• List to list
• Reductions
• Unfolding
• Predicates
• Partitioning
• Indexing
• Set operations
• Other list operations
• Tree operations
• Threading macros
• Binding
• Side effects
• Destructive operations
• Function combinators