I'm having some trouble spec'ing a fn that walks maps allowing you to hyphenate keys etc. I wonder if someone can point out my mistake as I'm having a hard time decrypting the error message…

(defn walk-map
  "Recursively apply a function to all map entries. When map is nil returns an
  empty map."
  [f m]
  (if m
    (walk/postwalk (fn [x] (if (map? x) (into {} (map f x)) x)) m)
    {}))

(s/fdef walk-map
  :args (s/cat :f (s/fspec :args (s/tuple ::s/any ::s/any) :ret ::kv)
               :m ::maybe-any-map)
  :ret ::any-map)

(defn hyphenate-keys
  "Recursively transforms all map keys from underscored strings to hyphenated
  keywords."
  [m]
  (walk-map (fn [[k v]] [(hyphenated-keyword k) v]) m))

(s/fdef hyphenate-keys
  :args (s/cat :m ::maybe-any-map)
  :ret ::any-map)

The error:

ERROR in (t-hyphenate-keys) (core.clj:4631)
expected: (= (sut/hyphenate-keys {:a 1, "a" 2}) {:a 2})
  actual: clojure.lang.ExceptionInfo: Call to #'example.common/walk-map did not conform to spec:
In: [0] val: ({}) fails at: [:args :f] predicate: (apply fn),  nth not supported on this type: PersistentArrayMap
:clojure.spec/args  (#object[example.common$hyphenate_keys$fn__20568 0x754a38a0 "ex[email protected]"] {:a 1, "a" 2})

I've tried a s/cat to capture ::s/any but I'm sure I'm missing something.

With the s/cat that I'd expect I need:

ERROR in (t-walk-map) (core.clj:4631)
expected: (= (sut/walk-map (fn [[k v]] [(name k) (if (number? v) (inc v) v)]) {:a 1, :b {:c 2, :d {:e 3}}}) {"a" 2, "b" {"c" 3, "d" {"e" 4}}})
  actual: clojure.lang.ExceptionInfo: Call to #'example.common/walk-map did not conform to spec:
In: [0] val: ([[] []]) fails at: [:args :f] predicate: (apply fn),  clojure.lang.PersistentVector cannot be cast to clojure.lang.Named
:clojure.spec/args  (#object[example.common_test$fn__21912$fn__21926 0x7787a602 "example.common_te[email protected]"] {:a 1, :b {:c 2, :d {:e 3}}})

(s/fdef walk-map
  :args (s/cat :f (s/fspec :args (s/cat :kv ::s/any) :ret ::kv)
               :m ::maybe-any-map)
  :ret ::any-map)

Shouldn't an fspec with :args (s/cat :kv ::s/any) match any and all args?

This is what's confusing me. This spec looks right, but doesn't work in the fspecs :args.

(s/explain-data (s/cat :kv (s/tuple ::s/any ::s/any)) [[:a {:b 2}]])

what is your hyphenated-keyword fn doing? I’m not sure I’m following what’s happening there, but it looks like it’s blowing up in that function, and that’s causing the spec failure

(defn- hyphenated-keyword
  [x]
  (if (or (string? x) (keyword? x))
    (-> x keyword->string infl/hyphenate keyword)
    x))

The relevant specs I'm using:

(s/def ::any-map
  (s/map-of (s/nilable ::s/any) (s/nilable ::s/any)))

(s/def ::maybe-any-map
  (s/nilable ::any-map))

Not sure if ::s/any is already nilable… 🙂

In the walk-map test I get a cast exception:

ERROR in (t-walk-map) (core.clj:4631)
expected: (= (sut/walk-map (fn [[k v]] [(name k) (if (number? v) (inc v) v)]) {:a 1, :b {:c 2, :d {:e 3}}}) {"a" 2, "b" {"c" 3, "d" {"e" 4}}})
  actual: clojure.lang.ExceptionInfo: Call to #'example.common/walk-map did not conform to spec:
In: [0] val: ([[] []]) fails at: [:args :f] predicate: (apply fn),  clojure.lang.PersistentVector cannot be cast to clojure.lang.Named
:clojure.spec/args  (#object[example.common_test$fn__21912$fn__21926 0x5ea46e79 "example.common_te[email protected]"] {:a 1, :b {:c 2, :d {:e 3}}})

ERROR in (t-underscore-keys) (core.clj:4631)
expected: (= (sut/underscore-keys {"a-b" 1}) {"a_b" 1})
  actual: clojure.lang.ExceptionInfo: Call to #'example.common/walk-map did not conform to spec:
In: [0] val: ([[] []]) fails at: [:args :f] predicate: (apply fn)
:clojure.spec/args  (#object[example.common$underscore_keys$fn__20550 0x1f36bed9 "[email protected]"] {"a-b" 1})

These error messages aren't intuitive. I've got a feeling this will be another thing newcomers to Clojure really struggle with.

This looks like it might help with the vague error message: https://github.com/clojure/clojure/commit/68fe71f0153bb6062754442c0a61c075b58fd9bc

It recurses into a ::pcat to expand out the error explanation, and I think I'm looking at a ::pcat above.

Okay, so only the commented out test fails:

(deftest t-walk-map
  (are [f m x] (= (sut/walk-map f m) x)
    identity nil    {}
    identity {}     {}
    identity {:a 1} {:a 1}

    ;; (fn [[k ^long v]] [(name k) (if (number? v) (inc v) v)])
    ;; {:a 1 :b {:c 2 :d {:e 3}}}
    ;; {"a" 2 "b" {"c" 3 "d" {"e" 4}}}
    ))

Okay. Looks like spec was exercising my walk-map with keys like [] and (). I was then calling name on vectors etc.

Fixed that by making my test fn valid. 🙂

(deftest t-walk-map
  (are [f m x] (= (sut/walk-map f m) x)
    identity nil    {}
    identity {}     {}
    identity {:a 1} {:a 1}

    (fn [[k v]]
      [(if (named? k) (name k) k)
       (if (number? v) (inc ^long v) v)])
    {:a 1 :b {:c 2 :d {:e 3}}}
    {"a" 2 "b" {"c" 3 "d" {"e" 4}}}))

One down. One to go!

ERROR in (t-underscore-keys) (core.clj:4631)
expected: (= (sut/underscore-keys nil) {})
  actual: clojure.lang.ExceptionInfo: Call to #'example.common/walk-map did not conform to spec:
In: [0] val: ([[] []]) fails at: [:args :f] predicate: (apply fn)
:clojure.spec/args  (#object[example.common$underscore_keys$fn__20550 0x6dd8e64b "[email protected]"] nil)

I wonder if it's the same problem. I need to make sure I have named keys.

It was. Because I had enabled instrumentation my functions were being called with vectors, sets, etc. and those weren't supported.

so i'm converting from schema, and i'm having some issues with respect to preventing clutter within my namespace. maybe i'm not structuring my data correctly

ex. `(def TextBlock {:type (schema/eq "Text") :foreground-color Color :background-color Color :style {(schema/optional-key :bold) schema/Bool (schema/optional-key :underline) schema/Bool (schema/optional-key :italic) schema/Bool} :text Letter}) (s/def ::foreground-color ::color) (s/def ::background-color ::color) (s/def ::style (s/keys :opt-un [::bold ::underline ::italic])) (s/def ::textblock (s/keys :req-un [::type ::foreground-color ::background-color ::style]))`

how would I apply s/def to ::bold, ::underline and ::italic, without s/def? I don't want those in the namespace

if I did have them in the namespace, i'd prefer to have them called something like ::font-style-underline, but the underlying spec would need to accept :underline as the style key

Is there any way to do this? I'm confused on whether I should be inlining the spec stuff. I'm sticking to what I did with plumatic.schema by placing all of my schemas in one file called schemas.cljs

@benzap: I don't think you can. You need to def the keywords in order to enable reuse.

And I'd think you only want really common schema in a global namespace as spec is embracing namespaced keywords.

So, :font/bold and :font/underline instead of :schemas/font-style-underline etc.

I've used specs like :common/any-map because I want nilable maps in a lot of places, but there might be a better way I haven't yet found.

(And I've done away completely with my shared schema namespaces for now.)

@jcf: I see, so I guess i'll have to start embracing namespaced keywords as well 🙂

I already have a font.cljs, would it be common to place spec in-line with the code?

That's what I'm doing, and what I've seen in all the examples.

It makes sense keeping everything starting with font in font.cljs; that's where I'd look at least!

Hrm, is there a way to specify a transform to a spec's conformed data?

I'm speccing datomic query, which accepts either a list or a map, and I'd like them to conform the same way

Found it! Looks like clojure.spec/conformer is what I was after.

I haven't seen this discussed elsewhere, but as a warning, protocol functions called in a non-higher order way (where clojure knows the protocol function is being called an creates an optimized call site for it) don't properly check args and returns against specs if instrumented