Make spec-coerce an optional dependency

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Brief

✨ Discussion piece ✨

spec-coerce isn't a common dependency for us, so i'd like to make it optional. Either by excluding the dependency in consumers (opt-out) or adding the dependency by consumers who want to use it (opt-in) or removing it altogether. In this PR i make coerce-map-indicating-invalidity opt-in.

Alternative 1: keep spec-coerce in project.clj and exclude in consumers (made possible by the 'requiring-resolve'-call).
Alternative 2: Remove function, bump major to 2.0.0

context:

• also components.pedestal uses spec-coerce: https://github.com/nedap/components.pedestal/blob/c4faad869634eaeab12a82a264cf2cb0a6ed6e76/src/nedap/components/pedestal/interceptors/spec_coercer.clj#L14
• utils.spec.predicates extends spec-coerse: https://github.com/nedap/utils.spec.predicates/blob/da4a1216788e50c5aa5aa894127648c0c2a42bd3/src/nedap/utils/spec/predicates.cljc#L89-L94

WDYT @nedap/sts-clojure-dev ?

QA plan

Author checklist

• I have QAed the functionality
• The PR has a reasonably reviewable size and a meaningful commit history
• I have run the branch formatter and observed no new/significative warnings
• The build passes
• I have self-reviewed the PR prior to assignment
• Additionally, I have code-reviewed iteratively the PR considering the following aspects in isolation:
  • Correctness
  • Robustness (red paths, failure handling etc)
  • Modular design
  • Test coverage
  • Spec coverage
  • Documentation
  • Security
  • Performance
  • Breaking API changes
  • Cross-compatibility (Clojure/ClojureScript)

Reviewer checklist

• I have checked out this branch and reviewed it locally, running it
• I have QAed the functionality
• I have reviewed the PR
• Additionally, I have code-reviewed iteratively the PR considering the following aspects in isolation:
  • Correctness
  • Robustness (red paths, failure handling etc)
  • Modular design
  • Test coverage
  • Spec coverage
  • Documentation
  • Security
  • Performance
  • Breaking API changes
  • Cross-compatibility (Clojure/ClojureScript)

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Given that the cljs testsuite broke, a major bump and removing the function all-together may be the path of least resistance.

[vemv]

Perhaps this would work?

;; defined in a separate .clj file
(defmacro when-spec-coerce-available [& body]
  (when (try
          (require 'spec-coerce.core)
          true
          (catch Exception _
            false))
    (do
      ~@body)))

;; no reader conditional needed
(when-spec-coerce-available
  (defn coerce-map-indicating-invalidity ,,,))

Then you'd remove the requires entirely (because there are no conditional requires in cljs) - it would become up to the consumers to 1) provide the dep, and 2) declare the requires

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because there are no conditional requires in cljs

I thought this was fixed (https://anmonteiro.com/2016/10/clojurescript-require-outside-ns/) but with little cljs experience i'm probably mistaken.

Regarding the when-spec-coerce-available, we do a similar thing in f-s, https://github.com/nedap/formatting-stack/blob/541ffcf6341735a63ca451d4d8782f2feaf7aacb/src/formatting_stack/strategies.clj#L211-L228

It could even be a function, I think 🤔.

But this would still be a breaking change (consumers are forced to change their usage by adding a dep + require).

[vemv]

I thought this was fixed (https://anmonteiro.com/2016/10/clojurescript-require-outside-ns/)

It works only in the repl or similar environments, AFAIK

But this would still be a breaking change

Some breaking changes are better than others :) one has a migration path, the other not. It seems to play well with semver + a changelog

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one has a migration path, the other not

IMO the migration paths are similar. Adding the require + dependency to your project.clj vs moving the function into your project.

From what I can see in the github search / grep.app there's no (public!) usage of this fn anyway. Removing it likely has very little impact whichever option we pick.

[vemv]

I like using the affected fn for quick web projects