When s/spec is used to create a new sequential context, I can’t find a way to capture the sequential thing itself.

For example:

(s/def ::ingredient (s/cat :quantity number? :unit keyword?))
(s/def ::recipe (s/cat :amount (s/spec ::ingredient) :description string?))
(s/conform ::recipe [[2.0 :teaspoon] "Cinnamon"])
=> {:amount {:quantity 2.0, :unit :teaspoon}, :description "Cinnamon"}

Here, there seems to be no way to capture the [2.0 :teaspoon] vector object if I also want to match its contents.

@cfleming: you are matching its contents via the cat. If you want to receive the vector as the conformed value you could use coll-of to do a different kind of match or use a conformer to transform the matched result into any arbitrary structure

Probably the latter is what you want

is there a way to update a map spec? I’d like to say “this fn takes a foo map, and returns a foo map with an extra key added on”. It’d be nice to say (s/def bar (conj foo ::extra-key)), without specifying the keys of the second map explicitly

arg. repl development overwrites instrumentation

Question: why is the second argument (`retag`) necessary in a multi-spec expression? In the guide, it is the same as the dispatch function, and I don't see any use case where providing a different function would be beneficial. And if it's the same, naming it again is redundant, as it can be retrieved via the public field dispatchFn.

As an experiment, I’ve added an optional spec namespace to clojure.java.jdbc: https://github.com/clojure/java.jdbc/blob/master/src/main/clojure/clojure/java/jdbc/spec.clj — feedback welcome (the tests attempt to require that ns and instrument clojure.java.jdbc when running tests, so under 1.9.0 the specs are actually checked for all calls in the tests)

Is there any mechanism that will allow you to include possible exceptions as part of a spec?

How can I spec a function that takes an atom(x), where x conforms to a spec?

thinking something like atom-of instead of coll-of