farolero VS anomalies

You can use this library to get CL-style conditions and restarts in Clojure: https://github.com/IGJoshua/farolero

True, the CL REPL is more useful than the Clojure REPL, but CL has a 20-30 year head start in development. Plus, Clojure was developed as a hosted language, and runs on .NET, Javascript, JVM, and even Dart (in-progress).

Since exceptions are quite deeply integrated into those platforms (as opposed to conditions), it has "bled through" to the Clojure APIs, and, in turn, REPL.

Folks have written a CL-style condition/restart library for Clojure (https://github.com/IGJoshua/farolero) too.

conditions/restarts are also a possibility https://github.com/IGJoshua/farolero

Someone added conditions/restarts to Clojure: https://github.com/IGJoshua/farolero

It does allow errors to be caught by the Repl and just.hkw to handle them.

farolero

This is interesting tool[1] that allows much the same with Clojure

[1]: https://github.com/IGJoshua/farolero

https://github.com/IGJoshua/farolero This uses derive hierarchies to enable general error handling.

I'll do my best but there might be better explanations around the web.

I think an illustrative example would be this repo:

https://github.com/cognitect-labs/anomalies

These are basically re-usable, namespaced keywords. You might decide to use them or something similar in your program/system and some people do. Pretty neat: Their semantics are documented in the readme and the little bit of code in the repo defines a spec here https://github.com/cognitect-labs/anomalies/blob/master/src/....

You can read it as: any map that has these keywords as defined in the spec is an "anomaly".

Specs are open, non-exclusive so you can add more stuff to your structure and they still conform. (Note that the double colon before the keywords just mean "the current namespace defined at the top".)

Note that you don't need to define a spec for namespaced keywords. It's just a utility that leverages them. By themselves they already say "I can be used in a global context".

---

These keywords can be used from anywhere and by themselves. You don't need to carry around their context for them to work or have meaning. To contrast: for example a JSON field in a nested context might only make sense in that specific nesting context. Clojure namespaces are by convention globally unique.

Some examples:

- `:my.domain.accounting/refnumber`

- `:my.domain.ui/color` defined as `(or :my.domain.ui/rgb :my.domain.ui/hsl)` etc.

- `:my.domain.person/name` defined as a string if at all

- `:my.domain.event/type`

In this case i would typically use an exception which is caught at the layer that is calling into my handler, whether that's a standard ring handler or interceptor. I'd use exceptions similar to those describe in the cognitect anomalies library and map those to an error response at the level interacting with the request and calling my handler.