Add ifn? schema

CHANGELOG.md

@@ -14,6 +14,10 @@ We use [Break Versioning][breakver]. The version numbers follow a `<major>.<mino
 
 Malli is in [alpha](README.md#alpha).
 
+## 0.5.0 (2021-04-13)
+
+* Add `ifn?` predicate, [#416](https://github.com/metosin/malli/pull/416)
+
 ## 0.4.0 (2021-03-31)
 
 * `:nil` schema, [#401](https://github.com/metosin/malli/pull/401)

README.md

@@ -331,6 +331,22 @@ Using regular expressions:
 ; => false
 ```
 
+`ifn?` accepts any value that implements Clojure(Script)'s IFn:
+
+```clj
+(m/validate ifn? :keyword)
+; => true
+
+(m/validate ifn? [])
+; => true
+
+(m/validate ifn? {})
+; => true
+
+(s/validate ifn? 123)
+; => false
+```
+
 ## Serializable Functions
 
 Enabling serializable function schemas requires [sci](https://github.com/borkdude/sci) as external dependency. If

src/malli/clj_kondo.cljc

@@ -53,6 +53,7 @@
 (defmethod accept 'sequential? [_ _ _ _] :sequential)
 (defmethod accept 'ratio? [_ _ _ _] :int) ;;??
 (defmethod accept 'bytes? [_ _ _ _] :char-sequence) ;;??
+(defmethod accept 'ifn? [_ _ _ _] :ifn)
 
 (defmethod accept :> [_ _ _ _] :number) ;;??
 (defmethod accept :>= [_ _ _ _] :number) ;;??

src/malli/core.cljc

@@ -1752,7 +1752,8 @@
         #'boolean? #'string? #'ident? #'simple-ident? #'qualified-ident? #'keyword? #'simple-keyword?
         #'qualified-keyword? #'symbol? #'simple-symbol? #'qualified-symbol? #'uuid? #'uri? #?(:clj #'decimal?)
         #'inst? #'seqable? #'indexed? #'map? #'vector? #'list? #'seq? #'char? #'set? #'nil? #'false? #'true?
-        #'zero? #?(:clj #'rational?) #'coll? #'empty? #'associative? #'sequential? #?(:clj #'ratio?) #?(:clj #'bytes?)]
+        #'zero? #?(:clj #'rational?) #'coll? #'empty? #'associative? #'sequential? #?(:clj #'ratio?) #?(:clj #'bytes?)
+        #'ifn?]
        (reduce -register-var {})))
 
 (defn class-schemas []

src/malli/error.cljc

@@ -72,6 +72,7 @@
    #?@(:clj ['bytes? {:error/message {:en "should be bytes"}}])
    :re {:error/message {:en "should match regex"}}
    :=> {:error/message {:en "invalid function"}}
+   'ifn? {:error/message {:en "should be an ifn"}}
    :enum {:error/fn {:en (fn [{:keys [schema]} _]
                            (str "should be "
                                 (if (= 1 (count (m/children schema)))

src/malli/generator.cljc

@@ -223,6 +223,7 @@
 
 (defmethod -schema-generator :=> [schema options] (-=>-gen schema options))
 (defmethod -schema-generator :function [schema options] (-function-gen schema options))
+(defmethod -schema-generator 'ifn? [_ _] gen/keyword)
 (defmethod -schema-generator :ref [schema options] (-ref-gen schema options))
 (defmethod -schema-generator :schema [schema options] (generator (m/deref schema) options))
 (defmethod -schema-generator ::m/schema [schema options] (generator (m/deref schema) options))

test/malli/clj_kondo_test.cljc

@@ -29,6 +29,12 @@
              [:=> [:cat :int] [:int {:min 0}]]
              [:=> [:cat :int :int [:* :int]] :int]])
 
+(defn siren
+  [f coll]
+  (into {} (map (juxt f identity) coll)))
+
+(m/=> siren [:=> [:cat ifn? coll?] map?])
+
 (deftest clj-kondo-integration-test
 
   (is (= {:op :keys,
@@ -48,7 +54,9 @@
                             :ret :int},
                          :varargs {:args [:int :int {:op :rest, :spec :int}],
                                    :ret :int,
-                                   :min-arity 2}}}}}
+                                   :min-arity 2}}}
+              'siren
+              {:arities {2 {:args [:ifn :coll], :ret :map}}}}}
             (-> 'malli.clj-kondo-test
                 (clj-kondo/collect)
                 (clj-kondo/linter-config)

test/malli/core_test.cljc

@@ -698,6 +698,16 @@
 
         (is (= form (m/form schema))))))
 
+  (testing "ifn schemas"
+    (let [schema (m/schema ifn?)]
+      (is (true? (m/validate schema (fn []))))
+      (is (true? (m/validate schema (constantly 1))))
+      (is (true? (m/validate schema :keyword)))
+      (is (true? (m/validate schema #?(:clj (reify clojure.lang.IFn
+                                              (invoke [_] "Invoked!"))
+                                       :cljs (reify IFn
+                                              (-invoke [_] "Invoked!"))))))))
+
   (testing "fn schemas"
     (doseq [fn ['(fn [x] (and (int? x) (< 10 x 18)))
                 "(fn [x] (and (int? x) (< 10 x 18)))"]]

test/malli/error_test.cljc

@@ -423,6 +423,10 @@
              (m/explain 123)
              (me/humanize)))))
 
+(deftest ifn-test
+  (is (= ["should be an ifn"]
+         (me/humanize (m/explain ifn? 123)))))
+
 (deftest multi-error-test
   (let [schema [:multi {:dispatch :type}
                 ["plus" [:map [:value int?]]]

test/malli/json_schema_test.cljc

@@ -73,6 +73,7 @@
 
    [[:=> :cat int?] {} :fn]
    [[:function [:=> :cat int?]] {} :fn]
+   [ifn? {}]
 
    [integer? {:type "integer"}]
    #?@(:clj [[ratio? {:type "number"}]

test/malli/transform_test.cljc

@@ -710,6 +710,7 @@
                       [[:enum P1 "S" "M" "L"] "s" "S"]
                       [[:re P1 ".*"] "kikka" "KIKKA"]
                       [[:fn P1 'string?] "kikka" "KIKKA"]
+                      [[ifn? P1] "kikka" "KIKKA"]
                       [[:maybe P1 keyword?] "kikka" :KIKKA]
                       [[:vector PS keyword?] ["kikka"] [:KIKKA]]
                       [[:sequential PS keyword?] ["kikka"] [:KIKKA]]