Is it possible to use middleware `io.aviso/pretty` with Clojure CLI (deps.edn)?

[timothypratley]

“Pretty” does a great job of cleaning up stack traces as a Leiningen plugin. Is there a way I can have the behavior injected for a deps.edn project?

[alexmiller]

$ clj -Sdeps '{:deps {io.aviso/pretty {:mvn/version "0.1.37"}}}'
Clojure 1.10.0
user=> (use 'io.aviso.repl)
nil
user=> (install-pretty-exceptions)
nil
user=> (/ 1 0)
Execution error (ArithmeticException) at user/eval744 (REPL:1).
Divide by zero
user=> (pst)
        clojure.core/eval        core.clj: 3214
                      ...
      user$eval744.invoke  NO_SOURCE_FILE:    1
user$eval744.invokeStatic  NO_SOURCE_FILE:    1
                      ...
java.lang.ArithmeticException: Divide by zero
nil

[timothypratley]

Hi Alex! Thank you. Is there a concept of injections or middleware in ~/.clojure/deps.edn? that would activate this?

[alexmiller]

No, nothing like this. clj just runs clojure.main, which is just a program runner, so there are a variety of ways to have it run programs around your repl (which is of course, also just a program) if you like.

For example, you could create a script that injects pretty, then starts the repl:

$ cat myrepl.clj
((requiring-resolve 'io.aviso.repl/install-pretty-exceptions))
(clojure.main/main)

Then create a deps.edn with an alias that includes pretty and runs the script (this and the prior file could also be in your ~/.clojure dir, becoming available to all deps.edn projects):

$ cat deps.edn
{:aliases
 {:myrepl {:extra-deps {io.aviso/pretty {:mvn/version "0.1.37"}}
           :main-opts ["myrepl.clj"]}}}

Then start clj with your alias:

$ clj -A:myrepl
Clojure 1.10.0
user=> (/ 1 0)
java.lang.ArithmeticException: Divide by zero
user=> (pst)
clojure.core/eval    core.clj: 3214
              ...
     user/eval744  myrepl.clj:    1
              ...
java.lang.ArithmeticException: Divide by zero

There are of course an infinite number of ways to install/configure/start/prep your repl but you have full program-making capability at your fingertips.

[mjmeintjes]

You can also check out https://github.com/mbuczko/revolt. I’ve found it to be pretty useful for this type of situation, as you can create your own plugins and tasks and then load them using deps.edn aliases.

[timothypratley]

Thanks @alexmiller and @mjmeintjes ; I very much appreciate your direction in this matter.