Apply clj-kondo metadata to let-dataset macro

[radovanne]

Issue

While using tablecloth, clj-kondo doesn't apply proper linting to let-dataset macro.

Reason for fix

Clj-kondo by default doesn't recognise custom macros which makes it unpleasant to work with because it trows Unresolved symbol error where it shouldn't be.

Solution

As far as I know there are three possible ways to make clj-kondo behave properly.

1. Add {:clj-kondo/lint-as 'clojure.core/let} metadata to macro.

• this metadata tells clj-kondo to lint let-dataset as if it were a clojure.core/let.

2. Add {:clj-kondo/ignore [:unresolved-symbol]} metadata to macro.

• any error symbol can be placed in the list and clj-kondo will ignore it, :unresolved-symbol is just in our case.

3. Adjusting local .clj-kondo config, but that would resolve issue only for me.

Why I chose this approach

• I chose first approach and not the second one is because If we use second approach with ignore metadata, language-server-protocol fails to work inside that let-dataset binding. I was not able to:

1. See binding signature.
2. Jump to definition.
3. Jump to or list references where that binding is used.

• With first approach let-dataset macro behaves like normal let binding, that being said it will also show if some binding is not being used!
  eg:

(tc/let-dataset [x (range 1 6)
                 y 1
                 z (dfn/+ x y)])

In this example clj-kondo will inform us that binding z is not being used.

• If by any chance we don't want clj-kondo to inform us about unused binding we can add additional metadata key to metadata map.

(defmacro let-dataset
  {:clj-kondo/lint-as 'clojure.core/let
   :clj-kondo/ignore [:unused-binding]}  <--
  ([bindings] `(let-dataset ~bindings nil))
  ([bindings options]
   (let [cols (take-nth 2 bindings)
         col-defs (mapv vector (map keyword cols) cols)]
     `(let [~@bindings]
        (dataset ~col-defs ~options)))))

Question:

• Because of my inexperience with tablecloth and how it is used I am not sure if people would prefer to see which binding is not being used ( normal let binding behaviour ) or would they prefer to not see which binding is not being used?
• Adding underscore to binding name made clj-kondo ignore unused-binding like it should but I don't think that people would do that because that binding name will be visualised by Clay as column name or value.
• If people would prefer to not see that unused binding info from linter then I can add additional metadata.

[radovanne]

exporter/write-api! doesn't build macro as intended, it doesn't put macro metadata on it.
I will reopen when it is ready.