there is no such method - it is java.util.Date/from (was added in Java 1.8, should exist in Datomic cloud)

Sorry, that’s the method I meant to type. HEre’s the exception I see:

Execution error (ExceptionInfo) at datomic.core.require/anomaly! (require.clj:53).
Unable to load namespace for java.util.Date/from

(FWIW, this is running against Datomic Local, but I assume it’s high-fidelity with Datomic Cloud/Ion).

well I will hand over to Datomic team here ... :)

are quoted expressions expected to work?

I think they must be quoted.

(generally -otherwise they expression is evaluated before submission in the query.)

Surprisingly, this works (note the immediately executed thunk):

(let [{conn :datomic/connection} @user/sysref
      db (d/db conn)
      works-here (java.util.Date/from (java.time.Instant/now))]
  (d/q {:query '{:find [?xnow]
                 :in [$]
                 :where [[(#(java.util.Date/from ^java.time.Instant (java.time.Instant/now))) ?xnow]]} 
        :args [db]}))

https://docs.datomic.com/cloud/query/query-data-reference.html#built-in-functions This leads me to believe it’s a smaller set of allowable functions and not any arbitrary expression

https://docs.datomic.com/cloud/query/query-data-reference.html#calling-java-methods

This led me to believe that as long as the class was available on the classpath https://docs.datomic.com/cloud/query/query-data-reference.html#calling-static-methods

The fact that it works when buried inside a thunk leads me to believe that I either have the syntax wrong or there is a something wrong in the query parser.

have you tried your minimal with the type hint added?

(let [{conn :datomic/connection} @user/sysref
      db (d/db conn)
      works-here (java.util.Date/from (Instant/now))]
  (d/q {:query '{:find [?xnow]
                 :in [$]
                 :where [[(java.util.Date/from ^java.util.Date (java.time.Instant/now)) ?xnow]]} ; not here
        :args [db]}))

Yes. I’ve type-hinted everything to the point where the type hints overwhelmed me.

I got one of the type hints wrong in my example above, but correcting it does not solve the problem. Corrected version:

(let [{conn :datomic/connection} @user/sysref
      db (d/db conn)
      works-here (java.util.Date/from (java.time.Instant/now))]
  (d/q {:query '{:find [?xnow]
                 :in [$]
                 :where [[(java.util.Date/from ^java.time.Instant (java.time.Instant/now)) ?xnow]]} ; not here
        :args [db]}))

no nesting allowed

That makes sense… except why is my anonymous fn allowed?

the docs don't mention it

I too have noticed that in some cases.

not sure

take out your nesting and try again

Generally, I’m finding that anonymous functions solve a lot of issues with nesting. It appears as though a complex anonymous fn with typed db args works well.

but calling a side effect, especially clock/now is gross inside a query

pass that in as an ordinary arg

Yeah, this is just an example. The real work is computing a window around a db value and passing in now

(too much noise around the real issue)

can you describe the real work semantically? there is maybe a different way to accomplish

e.g. "window around db value"

Find db entities with an date attr before a cutoff that is a function of another attribute of the entity.

But, I can solve that problem in other ways (e.g. db fn).

a db fn is for transactions

Sorry, query fn.

The frustration is that I should be able to do it just in the query.

[?e :cutoff/inst ?x] [?e :date ?d] [(my-logic ?x) ?actual-cutoff] [(< ?d ?actual-cutoff)]

https://docs.datomic.com/cloud/query/query-data-reference.html#calling-clojure-functions

put the fn on the ion allow list

I know how to add a clojure fn … and if I have to, I’ll solve the problem that way (with deploy cycle). But why can’t it work with an inline fn?

the query clause is not an argument that accepts arbitrary code, even though it looks like it

That’s understandable. I hope this thread helps others that seek to find the boundary.

you can also do (map-or-filter (fn [ent] ...arbitrary logic) (d/index-pull ....))

not sure if your use-case is amenable to that

Possibly. FWIW, I’m finding that un-nesting doesn’t resolve the issue. What does seem to resolve the issue is avoiding the Class/method syntax and reverting to the (. class method) syntax.

So this, surprisingly, also works:

(let [{conn :datomic/connection} @user/sysref
      db (d/db conn)
      works-here (java.util.Date/from (java.time.Instant/now))]
  (d/q {:query '{:find [?xnow]
                 :in [$]
                 :where [[(. java.util.Date from ^java.time.Instant (java.time.Instant/now)) ?xnow]]} ; not here
        :args [db]}))

Nested, but removing the / syntax on Date/from.