Open, single dispatch polymorphism.
Leiningen dependency information:
[name.stadig/polyfn "2.0.0"]
Maven dependency information:
<dependency> <groupId>name.stadig</groupId> <artifactId>polyfn</artifactId> <version>2.0.0</version> </dependency>
Define a polyfn.
(require '[name.stadig.polyfn :refer [defpolyfn extend-polyfn]]) (defpolyfn foo [exp])
Define some implementations for specific types.
(extend-polyfn foo Long [exp] (inc exp)) (extend-polyfn foo String [exp] "Hello, World!")
Use it.
(foo 1) => 2 (foo "string") => "Hello, World!" (foo 1.0) => #<IllegalArgumentException java.lang.IllegalArgumentException: No implementation of polyfn: #'user/foo found for class: java.lang.Double>
Oops, there is no implementation for Double, let’s define one for java.lang.Number.
(extend-polyfn foo Number [exp] Number) (foo 1.0) => java.lang.Number
The rest of the implementations remain the same
(foo 1) => 2 (foo "string") => "Hello, World!"
Open, single dispatch polymorphism. Enjoy!
Copyright (c) Paul Stadig. All rights reserved. Portions Copyright (c) Paul Stadig and Rich Hickey. All rights reserved.
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