Add support for uri? in malli.transform (Clojure only)

With Reitit (0.7.0-alpha7), using the below route definition, I get a
failure during the coercion when passing the uri "http://example.com".

    ["/uri"
      {:post {:summary "Post a URI - fails coercion"
              :coercion reitit.coercion.malli/coercion
              :parameters {:body {:uri uri?}}
              :responses {200 {:body {:uri uri?}}}
              :handler (fn [{{{uri :uri} :body} :parameters}]
                         {:status 200 :body {:uri uri}})}}]]

When I replaced the :coercion with the Clojure Spec version, the
coercion works.

With this change the Malli coercer should also work.

I made it Clojure specific since it relies on `java.net.URI`.

src/malli/transform.cljc

@@ -6,6 +6,7 @@
   #?(:clj (:import (java.time Instant ZoneId)
                    (java.time.format DateTimeFormatter DateTimeFormatterBuilder)
                    (java.time.temporal ChronoField)
+                   (java.net URI)
                    (java.util Date UUID))))
 
 (def ^:dynamic *max-compile-depth* 10)
@@ -95,6 +96,17 @@
       x)
     x))
 
+#?(:clj
+   (defn -string->uri [x]
+     (if (string? x)
+       (try
+         (URI. x)
+         ;; TODO replace with URISyntaxException once we are on
+         ;; babashka >= v1.3.186.
+         (catch Exception _
+           x))
+       x)))
+
 #?(:clj
    (def ^DateTimeFormatter +string->date-format+
      (-> (DateTimeFormatterBuilder.)
@@ -221,6 +233,7 @@
    'uuid? -string->uuid
    'double? -number->double
    'inst? -string->date
+   #?@(:clj ['uri? -string->uri])
 
    :enum {:compile (-infer-child-compiler :decode)}
    := {:compile (-infer-child-compiler :decode)}
@@ -231,6 +244,7 @@
    :qualified-keyword -string->keyword
    :qualified-symbol -string->symbol
    :uuid -string->uuid
+   ;#?@(:clj [:uri -string->uri])
 
    :set -sequential->set})
 
@@ -244,6 +258,7 @@
    'qualified-symbol? -any->string
 
    'uuid? -any->string
+   #?@(:clj ['uri? -any->string])
 
    :enum {:compile (-infer-child-compiler :encode)}
    := {:compile (-infer-child-compiler :encode)}
@@ -253,7 +268,7 @@
    :qualified-keyword m/-keyword->string
    :qualified-symbol -any->string
    :uuid -any->string
-   ;:uri any->string
+   ;#?@(:clj [:uri -any->string])
    ;:bigdec any->string
 
    'inst? -date->string

test/malli/transform_test.cljc

@@ -3,7 +3,8 @@
             [clojure.test :refer [are deftest is testing]]
             [malli.core :as m]
             [malli.core-test]
-            [malli.transform :as mt]))
+            [malli.transform :as mt])
+  #?(:clj (:import (java.net URI))))
 
 (deftest ->interceptor-test
   (are [?interceptor expected]
@@ -67,6 +68,11 @@
   ;; Ensure that uuid0 is also a valid uuid
   (is (= #uuid "00000000-0000-0000-0000-000000000000" (mt/-string->uuid "00000000-0000-0000-0000-000000000000"))))
 
+#?(:clj
+   (deftest string->uri
+     (is (= (URI. "http://example.com") (mt/-string->uri "http://example.com")))
+     (is (= "broken link" (mt/-string->uri "broken link")))))
+
 (deftest string->date
   (is (= #inst "2018-04-27T18:25:37Z" (mt/-string->date "2018-04-27T18:25:37Z")))
   (is (= #inst "2018-04-27T18:25:37.100Z" (mt/-string->date "2018-04-27T18:25:37.1Z")))
@@ -115,6 +121,7 @@
 
 (deftest any->string
   #?(:clj (is (= "1/2" (mt/-any->string 1/2))))
+  #?(:clj (is (= "http://example.com" (mt/-any->string (URI. "http://example.com")))))
   (is (= "0.5" (mt/-any->string 0.5)))
   (is (= nil (mt/-any->string nil))))
 
@@ -996,7 +1003,17 @@
         (is (= {0 #uuid"2ac307dc-4ec8-4046-9b7e-57716b7ecfd2"
                 1 #uuid"820e5003-6fff-480b-9e2b-ec3cdc5d2f78"
                 2 #uuid"017de28f-5801-8c62-9ce9-cef70883794a"}
-               (m/decode schema data mt/json-transformer)))))))
+               (m/decode schema data mt/json-transformer))))))
+  #?(:clj
+     (let [schema [:map-of uri? uri?]
+           good "http://example.com"
+           bad "invalid url"
+           data {good good
+                 bad bad}]
+       (testing data
+         (is (= {(URI. good) (URI. good)
+                 bad bad}
+                (m/decode schema data mt/json-transformer)))))))
 
 #?(:clj
    (deftest -safe-test