Boot and the data_readers.clj file

[Malabarba]

@Naomarik reports here that the debugger isn't working in boot. The error indicates that boot doesn't see our data_readers.clj file at the root of the class path.

According to http://clojure.org/reader:

When Clojure starts, it searches for files named data_readers.clj at the root of the classpath. Each such file must contain a Clojure map of symbols, like this:

{foo/bar my.project.foo/bar
foo/baz my.project/baz}

Does anyone know if this might be a boot bug or if we're doing something wrong?

[bbatsov]

Pinging @micha.

[Naomarik]

I've found that (boot.core/load-data-readers!) will work once the repl is going, but I'm not sure where to put this so it does it automatically.
Reference: boot-clj/boot#47

[Malabarba]

Maybe cider-nrepl should do it? Though I'm not sure how.

[Malabarba]

Although, considering that this is a general Clojure thing, it would be nice if Boot handled it by default.

[camelpunch]

Bump. I've found that (boot.core/load-data-readers!) removes the error, but doesn't cause C-M-x to jump into the debugger when a #break is present.

[Malabarba]

@camelpunch There are some places where a #break doesn't work, so that might be unrelated to boot. Could you see if it works for you by hitting C-M-x in the following snippet?

(let [x 1]
  (inc #break x))

[camelpunch]

Yes, that works. Thanks!

[Malabarba]

If anyone here uses boot, I'd still like to know if there's any way to load forms on startup. Even if there's no way for cider to do it, we should add instructions to the Readme.

@alexander-yakushev You've been using boot lately, haven't you?

[alexander-yakushev]

I can confirm that doing (boot.core/load-data-readers) fixes the problem and the debugger works. Boot has an option to provide :eval form but only for the client — it doesn't work if REPL is started in server mode.

@Malabarba RE: debugger. Holy maker of pepperoni, I just tried it for the first time and it's frigging amazing! I didn't know that I've been missing so much :).

[Malabarba]

@alexander-yakushev Thanks ^^

I guess the best we can do then is load this form as part of cider-nrepl if the symbol boot.core/load-data-readers resolves to a var. @bbatsov what do you think?

[bbatsov]

I think it's a reasonable approach and I've heard no other suggestions, so let's get this done.

[alexander-yakushev]

I object, your honor.

First, boot.core/load-data-readers does nothing more but reloading readers
and setting root of data-readers to it.

Second, that fails when evaluated at the same time as middleware init,
because apparently Boot runs those in a separate thread, and I get 'setting
from non-binder thread' exception.

On Mon, Jan 11, 2016, 19:41 Bozhidar Batsov [email protected]
wrote:

I think it's a reasonable approach and I've heard no other suggestions, so
let's get this done.

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[bbatsov]

OK, I guess we're back to the drawing board then. :-)

[bbatsov]

@Malabarba Maybe we should at least document this problem somewhere?

[micha]

If there's anything I can do to help let me know. (I'm mostly a Vim user
though.)

Micha Niskin

On Mon, Jan 11, 2016 at 2:34 PM, Bozhidar Batsov [email protected]
wrote:

OK, I guess we're back to the drawing board then. :-)

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#1462 (comment)
.

[alexander-yakushev]

@micha How about having a separate :eval option that is evaluated by server rather than the one invoked by REPL client?

[Malabarba]

@micha It would be great if data_readers.clj was loaded by default when a boot REPL is started. The Clojure documentation states that this file is loaded automatically, so I think it makes sense for the REPL to behave the same way.

[bbatsov]

Yeah, that'd be a dream solution. :-)

[micha]

Sure, I can do that. Would you consider it a bugfix or feature? So I know
whether to land it in 2.6.0 or a patch release.

Micha Niskin

On Tue, Jan 12, 2016 at 1:57 AM, Bozhidar Batsov [email protected]
wrote:

Yeah, that'd be a dream solution. :-)

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.

[Malabarba]

I think I'd call it a bugfix, but it could definitely go either way.

[bbatsov]

Any progress with this?

[Malabarba]

While we wait for an upstream fix, I think I have a workaround. the debug.clj middleware can call (boot.core/load-data-readers!) when it receives the debug-init message. That only happens after the repl is connected, so I think it avoids the previous problem, right?

(of course, it will check whether that function exists first, so it won't error on non-boot projects)

[alexander-yakushev]

(of course, it will check whether that function exists first, so it won't error on non-boot projects)

There isn't much point in calling exactly Boot's function as it is nothing else but:

  (#'clojure.core/load-data-readers)
  (set! *data-readers* (.getRawRoot #'*data-readers*))

And calling that in Leiningen won't hurt either.

[Malabarba]

Even better.

[Malabarba]

Pushed Alex's snippet.

[tmarble]

Clojars is still based on the version clojure-emacs/cider-nrepl@1723057

I just did a local lein install with clojure-emacs/cider-nrepl@ebf3526 and that avoids the ugly stack trace (Can't set!: *data-readers* from non-binding thread)

FWIW I don't think the debugger is actually working as I tried C-u C-M-x, but that provoked a stack trace.

[Malabarba]

Sorry, I've redeployed now. If the debugger still doesn't work for you, please file a new issue.

[Malabarba]

Ignore the accidental close, the issue itself is very much still open.

[Malabarba]

@micha Has this made into a boot stable release?

[arichiardi]

@Malabarba It's been milestoned

[Malabarba]

@arichiardi Thanks for the notice!

[micha]

Attempted a fix with boot-clj/boot#439...does it work?

[bbatsov]

Guess someone should try this out.

[tmarble]

@micha OMG that works!

@Malabarba is there a current "cheatsheet" for the debugger? I've seen your blog, but I'm wondering if there is a current list keybindings (functions) and overview of what's possible? Sorry if this is obvious and I've missed it (ENOTENOUGHCOFFEE).

@bbatsov I just have to say CIDER is amazing! I love the docstring on mouseover symbol thing!

[bbatsov]

@Malabarba is there a current "cheatsheet" for the debugger? I've seen your blog, but I'm wondering if there is a current list keybindings (functions) and overview of what's possible? Sorry if this is obvious and I've missed it (ENOTENOUGHCOFFEE).

See http://cider.readthedocs.org/en/latest/extended_workflow/#debugging :-)

[tmarble]

@bbatsov Благодаря!!!

[Malabarba]

@tmarble indeed. The man page should always contain everything. And we try to keep the debugger features easily discoverable.

[Malabarba]

Ok. Since the fixed has been merged into boot master, I'm closing this issue. We should have a definitive fix when 2.6.0 comes out.

[zalky]

Hi all, is anyone still experiencing this issue?

I can load all the cider data readers:

boot.user> (load-data-readers!)
{db/id #'datomic.db/id-literal,
 db/fn #'datomic.function/construct,
 base64 #'datomic.codec/base-64-literal,
 ordered/set #'flatland.ordered.set/into-ordered-set,
 ordered/map #'flatland.ordered.map/ordered-map,
 dbg #'cider.nrepl.middleware.debug/debug-reader,     ; <- appears to be there
 break #'cider.nrepl.middleware.debug/breakpoint-reader,
 light #'cider.nrepl.middleware.enlighten/light-reader}

and I still get an error when the file is compiled:

clojure.lang.Compiler$CompilerException: java.lang.RuntimeException: No reader function for tag dbg

Cider version: 0.18.0
Boot version: 2.8.1