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| -rw-r--r-- | README.org | 18 |
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@@ -221,6 +221,24 @@ However, if target table is not empty, its type can be deduced: Note that when converting associative table into sequential table order is determined by the =pairs= function. Also note that if variable stores the table has both integer key 1, and other associative keys, the type will be the same as of sequential table. +** =defmulti= and =defmethod= +A bit more simple implementations of Clojure's =defmulti= and =defmethod=. +=defmulti= macros returns an empty table with =__call= metamethod, that calls dispatching function on its arguments. +Methods are defined inside =multimethods= table, which is also stored in the metatable. + +=defmethod= adds a new method to the metatable of given =multifn=. +It accepts the multi-fn table as its first argument, the dispatch value as second, and Fennel's arglist followed by the body: + +#+begin_src fennel + (defmulti fac (fn [x] x)) + + (defmethod fac 0 [_] 1) + (defmethod fac :default [x] (* x (fac (- x 1)))) + + (fac 4) ;; => 24 +#+end_src + +=:default= is a special method which gets called when no other methods were found for given dispatch value. * Functions Here are some important functions from the library. |