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Comment by bmillare | Hacker News Reader

Can you elaborate with an example for s/valid? on needing to preconfrom your data. I have not had this issue.

Also note for others with regard to eagerness, this is only for maps. "When conformance is checked on a map, it does two things - checking that the required attributes are included, and checking that every registered key has a conforming value. We’ll see later where optional attributes can be useful. Also note that ALL attributes are checked via keys, not just those listed in the :req and :opt keys. Thus a bare (s/keys) is valid and will check all attributes of a map without checking which keys are required or optional."

Can you explain the point of :opt with s/keys if it will always check any registered spec in if present?

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> Can you elaborate with an example for s/valid? on needing to preconfrom your data. I have not had this issue.

If you have any conformers, s/valid? will use them before validating.

So, if you have a 'set' conformer, for example, s/valid? will tell you that the data is valid even if the value is not a set, but a vector, for example.

Your code must explicitly call 'conform', checking with s/valid? is not enough.

Found the answer to s/keys and :opt "The :opt keys serve as documentation and may be used by the generator."

The important aspect to keep in mind is that it makes the key optional, not the value of the key.

Thus if you have a map without the key, the value won't be validated. But if the key is present, then it will validate its value.

If you want to make the value of the key optional, in the spec for the value of the key, you need to add `nil?` as a valid value.

> Thus if you have a map without the key, the value won't be validated. But if the key is present, then it will validate its value.

Exactly. Which is something I did not expect. I expected '(s/valid? ::my-spec x)' to tell me if x is valid according to ::my-spec, checking only those keys that ::my-spec lists in :req and :opt (if present).

For maps, you might as well think of s/valid? as ignoring the first parameter. It validates anything it can.

Oh, you mean because it will validate even qualified keys that arn't defined on req and opt if they have a corresponding spec?

I admit, that's surprising. Not sure why they made it so.

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