-> an implementation of polymorphism in Clojure
What Clojure doc says:
A Clojure multimethod is a combination of a dispatching function, and one or more methods. When a multimethod is defined, using defmulti, a dispatching function must be supplied. This function will be applied to the arguments to the multimethod in order to produce a dispatching value.
It's easier to understand when looking at an example. Here's an example from Clojure for the brave and true:
That's how a multimethod is defined:
(ns were-creatures)
(defmulti full-moon-behavior
(fn [were-creature]
(:were-type were-creature)))
(defmethod full-moon-behavior :wolf
[were-creature]
(str (:name were-creature) " will howl and murder"))
(defmethod full-moon-behavior :simmons
[were-creature]
(str (:name were-creature) " will encourage people and sweat to the oldies"))And now that's how the multimethod is used:
(full-moon-behavior {:were-type :wolf
:name "Rachel from next door"})
; => "Rachel from next door will howl and murder"
(full-moon-behavior {:name "Andy the baker"
:were-type :simmons})
; => "Andy the baker will encourage people and sweat to the oldies"