Support recursive in get-in

[obeah]

Hi,

it seems recursive is not supported by get-in. Was it omitted on purpose?
With small modifications it works for my use case:

(defn- unwrap-recursive [m]
  (cond
    (recursive? m) (deref (:derefable m)) ; probably use schema-value
    :else m))

(defn- get-in-schema [m k & [default]]
  (unwrap-recursive (unwrap-sequence-schemas (get m (key-in-schema m k) default))))

[Deraen]

Yes, it was reverted on purpose. Using schema-value proved too unpredictable and broke existing code: 240f8a5

[Deraen]

We are interested in finding a way to support this. Ideas welcome.

Some ideas here: #8 (comment)

[ikitommi]

Could there be a separately special get-in-value, which would walk over schema Records?

[Deraen]

Perhaps. I think -value postfix doesn't clearly indicate that Schema values would be walked over all along the path. Maybe -values is better?

[ikitommi]

There is already get-schema-value which walks over one level and is documented "Returns the sub-schema or sub-schemas of given schema.". So, get-in-schema-value could be coherent name...

[obeah]

Thanks. I understand the problem with "conditional", "maybe" etc. (actually will be doing some special form of get-in for my particular use case of "conditional" - it will return a union of values for all possible branches). As for "recursive" I definitely missing smth - it seems to me it would be just enough to resolve it to actual underlying schema and continue but you obviously encountered some issues with that.

[Deraen]

@obeah It is also somewhat unpredictable with recursive:

(get-in {:a {:b (s/recursive Foo)}} [:a :b])
;; Foo
;; or (s/recursive Foo) ?

[obeah]

thanks, got it. It seems that for this particular case, current implementation returns recursive, not underlying schema:
(get-in {:a {:b (s/recursive Foo)}} [:a :b])

But for the case when caller wants to go one or more levels deeper then it seems reasonable to resolve "recursive" to actual schema and continue.
So (get-in {:a {:b (s/recursive Foo)}} [:a :b :key-in-foo]) would return schema for :key-in-foo.