Ability to expand macros which use &env

[darkleaf]

Hi!
Is any plans to use ztellman/riddley for macro expansion and debugging?

Related to

• Can't debug forms that contain macros that use &env cider#1775
• Debugger breaks on macros that require &env (like async.core/go) cider-nrepl#372

[bbatsov]

Hey there!

There are no plans to use it (I'm not familiar with the library). In general 3rd party libraries can be integrated only at the middleware level, as Orchard is supposed to be self-contained by design.

[darkleaf]

Cider can't debug and expand macros which uses &env argument. Riddley can expand such macros correctly.

[bbatsov]

Understood. I'll take a closer look at the issue when I can, but everyone's more than welcome to beat me to it. I see riddley is a small library, so we can either emulate its approach in Orchard or leverage it directly in cider-nrepl.

[Cartmanishere]

I think there are challenges in directly using ridley.walk/macroexpand-all instead of orchard.meta/macroexpand-all.

In the library's macroexpand function, even inline function call are checked for macroexpansion.
E.g

(ridley.walk/macroexpand-all '(+ 1 2)
=> (. clojure.lang.Numbers (add 1 2))

(orchard.meta/macroexpand-all '(+ 1 2)
=> (+ 1 2)

This change in behavior will break some things down the line in debugging.

One other problem is that orchard's macroexpand attaches the original-form in the metadata. Technically there is a way to be figured out to do the same thing using the predicate and handler provided by ridley.walk/macroexpand-all. But again, there is potential for breaking the further debugging code.

Related:
clojure-emacs/cider#1775
clojure-emacs/cider-nrepl#373

[vemv]

In face of the caveats that @Cartmanishere mentions, and observing that riddley hasn't been maintained for a while and that clojure-emacs/cider#1775 is closed, we can close this one as well.

Of course, a motivated hacker can pick up the task but it doesn't look like we gain much by tracking it today.