cond-plus

An adaption of the Racket cond macro for Clojure.

Usage

The below takes inspiration from the Racket docs:

(cond+ & cond-clause)

cond-clause = [test-expr & body]
            | [test-expr :> fn-expr]
            | [test-expr]
            | [:else & body]

Each test-expr is evaluated one at a time. If the test-expr returns logical true (or is :else), the form is evaluated as described below and no further cond-clauses are evaluated. (cond+) returns nil.

[test-expr & body]

Evaluates body in an implicit do.

[test-expr :> fn-expr]

fn-expr must be a function that accepts one argument. The result of the test-expr is passed to the fn-expr and that result is returned.

=> is also accepted.

[test-expr]

The result of the test-expr is returned.

[:else & body]

If an [:else & body] is present, it must be the last cond-clause and it must be the only :else clause. Evaluates body in an implicit do.

else is also accepted.

> (cond+)
nil
> (cond+
   [:else 5])
5
> (cond+
   [(pos? -5) "doesn't get here"]
   [(zero? -5) "doesn't get here, either"]
   [(neg? 5) :here])
:here
> (cond+
   [(next [1 2 3]) :> (fn [x] (map - x))])
[-2 -3]
> (cond+
   [(next [1 2 3])])
[2 3]

License

Copyright © 2020 Noah Bogart

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.