From dd52e5dfff8ed0c057a02990a25f7e1a7ec4c75f Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Sun, 22 Aug 2021 17:03:48 +0300
Subject: [PATCH 01/11] m/-set-children doesn't recreate identical schemas

* identity walking is order(s) of magnitude faster
---
 perf/malli/creation_perf_test.cljc | 30 +++++++++++++++++++++---------
 src/malli/core.cljc                |  7 +++++--
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/perf/malli/creation_perf_test.cljc b/perf/malli/creation_perf_test.cljc
index 52b0f550d..5aa6216d5 100644
--- a/perf/malli/creation_perf_test.cljc
+++ b/perf/malli/creation_perf_test.cljc
@@ -4,12 +4,15 @@
             [malli.core :as m]
             [malli.util :as mu]))
 
+(defmacro bench [& body]
+  `(cc/quick-bench ~@body))
+
 (defmacro profile [& body]
   `(let [start# (System/currentTimeMillis)]
      (dotimes [_# 100000] ~@body)
      (let [ms# (- (System/currentTimeMillis) start#)
            times# (int (/ 1000000000 ms#))]
-       (print "invoking" times# "times")
+       (println "invoking" times# "times")
        (time (prof/profile (dotimes [_# times#] ~@body))))))
 
 (defmacro profile-for
@@ -48,21 +51,21 @@
   ;;
 
   ;; 5.2µs
-  (cc/quick-bench (m/validate [:or :int :string] 42))
+  (bench (m/validate [:or :int :string] 42))
   (profile (m/validate [:or :int :string] 42))
 
   ;; 3.0µs
-  (cc/quick-bench (m/schema [:or :int :string]))
+  (bench (m/schema [:or :int :string]))
   (profile (m/schema [:or :int :string]))
 
   ;; 1.7µs
   (let [schema (m/schema [:or :int :string])]
-    (cc/quick-bench (m/validator schema))
+    (bench (m/validator schema))
     #_(profile (m/validator schema)))
 
   ;; 4ns
   (let [validate (m/validator [:or :int :string])]
-    (cc/quick-bench (validate 42))
+    (bench (validate 42))
     #_(profile (validate 42))))
 
 (def ?schema
@@ -75,6 +78,8 @@
 
 (def schema (m/schema ?schema))
 
+(def leaf-schema (m/schema :int))
+
 (comment
 
   ;;
@@ -82,11 +87,11 @@
   ;;
 
   ;; 480ns
-  (cc/quick-bench (m/schema :int))
+  (bench (m/schema :int))
   (profile (m/schema :int))
 
   ;; 44µs
-  (cc/quick-bench (m/schema ?schema))
+  (bench (m/schema ?schema))
   (profile (m/schema ?schema)))
 
 (comment
@@ -95,12 +100,19 @@
   ;; schema transformation
   ;;
 
+  ;; 271ns
+  ;; 14ns (-set-children, -set-properties)
+  (bench (m/walk leaf-schema (m/schema-walker identity)))
+  (profile (m/walk leaf-schema (m/schema-walker identity)))
+
   ;; 26µs
-  (cc/quick-bench (m/walk schema (m/schema-walker identity)))
+  ;; 1.3µs (-set-children, -set-properties)
+  (bench (m/walk schema (m/schema-walker identity)))
   (profile (m/walk schema (m/schema-walker identity)))
 
   ;; 51µs
-  (cc/quick-bench (mu/closed-schema schema))
+  ;; 44µs (-set-children, -set-properties)
+  (bench (mu/closed-schema schema))
   (profile (mu/closed-schema schema)))
 
 (comment
diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index d7fad3c86..2fe74e319 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -170,6 +170,8 @@
 
 (defn -update [m k f] (assoc m k (f (get m k))))
 
+(defn -equals [x y] (or (identical? x y) (= x y)))
+
 (defn -memoize [f]
   (let [value #?(:clj (AtomicReference. nil), :cljs (atom nil))]
     (fn [] #?(:clj (or (.get value) (do (.set value (f)) (.get value))), :cljs (or @value (reset! value (f)))))))
@@ -181,7 +183,8 @@
   (mapv (fn [[k s]] [k (-properties s) (-inner walker s (conj path k) options)]) entries))
 
 (defn -set-children [schema children]
-  (-into-schema (-parent schema) (-properties schema) children (-options schema)))
+  (if (-equals children (-children schema))
+    schema (-into-schema (-parent schema) (-properties schema) children (-options schema))))
 
 (defn -update-options [schema f]
   (-into-schema (-parent schema) (-properties schema) (-children schema) (f (-options schema))))
@@ -398,7 +401,7 @@
                   (-intercepting (-value-transformer transformer this method options)))
                 (-walk [this walker path options]
                   (if (-accept walker this path options)
-                    (-outer walker this path (vec children) options)))
+                    (-outer walker this path children options)))
                 (-properties [_] properties)
                 (-options [_] options)
                 (-children [_] children)

From 42a3e64c01b5fad11faf45d2958c09570c8bf7c3 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Sun, 22 Aug 2021 17:04:13 +0300
Subject: [PATCH 02/11] cleanup

---
 src/malli/core.cljc | 4 ++++
 src/malli/util.cljc | 6 +-----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 2fe74e319..5d925c6e1 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -186,6 +186,10 @@
   (if (-equals children (-children schema))
     schema (-into-schema (-parent schema) (-properties schema) children (-options schema))))
 
+(defn -set-properties [schema properties]
+  (if (-equals properties (-properties schema))
+    schema (-into-schema (-parent schema) properties (-children schema) (-options schema))))
+
 (defn -update-options [schema f]
   (-into-schema (-parent schema) (-properties schema) (-children schema) (f (-options schema))))
 
diff --git a/src/malli/util.cljc b/src/malli/util.cljc
index a5f389cc3..2cf60baca 100644
--- a/src/malli/util.cljc
+++ b/src/malli/util.cljc
@@ -116,11 +116,7 @@
   "Returns a Schema instance with updated properties."
   [?schema f & args]
   (let [schema (m/schema ?schema)]
-    (m/into-schema
-      (m/-parent schema)
-      (not-empty (apply f (m/-properties schema) args))
-      (m/-children schema)
-      (m/-options schema))))
+    (m/-set-properties schema (not-empty (apply f (m/-properties schema) args)))))
 
 (defn closed-schema
   "Closes recursively all :map schemas by adding `{:closed true}`

From af0efd08a5d6ff6943bebaaacb15d7dc063a6c62 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Sun, 22 Aug 2021 23:59:36 +0300
Subject: [PATCH 03/11] faster m/-create-form

---
 perf/malli/creation_perf_test.cljc |  7 +++++++
 src/malli/core.cljc                | 10 +++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/perf/malli/creation_perf_test.cljc b/perf/malli/creation_perf_test.cljc
index 5aa6216d5..e22ee8bde 100644
--- a/perf/malli/creation_perf_test.cljc
+++ b/perf/malli/creation_perf_test.cljc
@@ -115,6 +115,13 @@
   (bench (mu/closed-schema schema))
   (profile (mu/closed-schema schema)))
 
+(comment
+
+  (let [t ::or, p {:a 1}, c (mapv m/schema [:int :int])]
+    ;; 480ns
+    ;; 221ns (faster impl)
+    (bench (m/-create-form t p c))))
+
 (comment
   (prof/serve-files 8080)
   (prof/clear-results))
diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 5d925c6e1..0d0a12544 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -135,11 +135,11 @@
     (-fail! ::child-error (merge {:type type, :properties properties, :children children} opts))))
 
 (defn -create-form [type properties children]
-  (cond
-    (and (seq properties) (seq children)) (into [type properties] children)
-    (seq properties) [type properties]
-    (seq children) (into [type] children)
-    :else type))
+  (let [has-children (seq children), has-properties (seq properties)]
+    (cond (and has-properties has-children) (reduce conj [type properties] children)
+          has-properties [type properties]
+          has-children (reduce conj [type] children)
+          :else type)))
 
 (defn -pointer [id schema options] (-into-schema (-schema-schema {:id id}) nil [schema] options))
 

From c97ade630f6f7e9876e5e22af7a0787b5bca675b Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 08:43:15 +0300
Subject: [PATCH 04/11] faster -val-schema

---
 perf/malli/creation_perf_test.cljc |  9 +++++++++
 src/malli/core.cljc                | 23 ++++++++++++-----------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/perf/malli/creation_perf_test.cljc b/perf/malli/creation_perf_test.cljc
index e22ee8bde..a503386c7 100644
--- a/perf/malli/creation_perf_test.cljc
+++ b/perf/malli/creation_perf_test.cljc
@@ -122,6 +122,15 @@
     ;; 221ns (faster impl)
     (bench (m/-create-form t p c))))
 
+(comment
+  (let [s (m/schema :int)]
+    ;; 440ns
+    ;; 341ns (-create-form)
+    ;; 150ns (delayed form)
+    ;;  30ns (don't -check-children)
+    (bench (m/-val-schema s nil))
+    (profile (m/-val-schema s nil))))
+
 (comment
   (prof/serve-files 8080)
   (prof/clear-results))
diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 0d0a12544..11f4dc000 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -130,9 +130,10 @@
 (defn -unlift-keys [m prefix]
   (reduce-kv #(if (= (name prefix) (namespace %2)) (assoc %1 (keyword (name %2)) %3) %1) {} m))
 
-(defn -check-children! [type properties children {:keys [min max] :as opts}]
-  (if (or (and min (< (count children) min)) (and max (> (count children) max)))
-    (-fail! ::child-error (merge {:type type, :properties properties, :children children} opts))))
+(defn -check-children! [type properties children opts]
+  (let [size (count children), min (:min opts 0), max (:max opts size)]
+    (when (or (< size min) (> size max))
+      (-fail! ::child-error {:type type, :properties properties, :children children, :min min, :max max}))))
 
 (defn -create-form [type properties children]
   (let [has-children (seq children), has-properties (seq properties)]
@@ -640,7 +641,7 @@
 
 (defn -val-schema
   ([schema properties]
-   (-into-schema (-val-schema) properties [schema] (-options schema)))
+   (-into-schema (-val-schema) properties (list schema) (-options schema)))
   ([]
    ^{:type ::into-schema}
    (reify IntoSchema
@@ -649,9 +650,9 @@
      (-properties-schema [_ _])
      (-children-schema [_ _])
      (-into-schema [parent properties children options]
-       (-check-children! ::val properties children {:min 1, :max 1})
-       (let [[schema :as children] (map #(schema % options) children)
-             form (-create-form ::val properties (map -form children))]
+       #_(-check-children! ::val properties children {:min 1, :max 1})
+       (let [schema (schema (first children) options)
+             form (delay (-create-form ::val properties [(-form schema)]))]
          ^{:type ::schema}
          (reify Schema
            (-validator [_] (-validator schema))
@@ -659,17 +660,17 @@
            (-parser [_] (-parser schema))
            (-unparser [_] (-unparser schema))
            (-transformer [this transformer method options]
-             (-parent-children-transformer this children transformer method options))
+             (-parent-children-transformer this (list schema) transformer method options))
            (-walk [this walker path options]
              (if (::walk-entry-vals options)
                (if (-accept walker this path options)
-                 (-outer walker this path [(-inner walker schema path options)] options))
+                 (-outer walker this path (list (-inner walker schema path options)) options))
                (-walk schema walker path options)))
            (-properties [_] properties)
            (-options [_] (-options schema))
-           (-children [_] children)
+           (-children [_] [schema])
            (-parent [_] parent)
-           (-form [_] form)
+           (-form [_] @form)
            LensSchema
            (-keep [_])
            (-get [_ key default] (if (= 0 key) schema default))

From 0e0632a0834ccc6b18c332d8bbe8e7e13b4d9a2d Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 09:14:38 +0300
Subject: [PATCH 05/11] fix -check-children

---
 src/malli/core.cljc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 11f4dc000..99aa41402 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -131,7 +131,7 @@
   (reduce-kv #(if (= (name prefix) (namespace %2)) (assoc %1 (keyword (name %2)) %3) %1) {} m))
 
 (defn -check-children! [type properties children opts]
-  (let [size (count children), min (:min opts 0), max (:max opts size)]
+  (let [size (count children), min (or (:min opts) 0), max (or (:max opts) size)]
     (when (or (< size min) (> size max))
       (-fail! ::child-error {:type type, :properties properties, :children children, :min min, :max max}))))
 

From 6d108e4b5c8bf3599f96167ff95d490ff0eb28fb Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 09:14:48 +0300
Subject: [PATCH 06/11] polish registry-code

---
 src/malli/registry.cljc | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/src/malli/registry.cljc b/src/malli/registry.cljc
index 9fb6cf74a..219be725e 100644
--- a/src/malli/registry.cljc
+++ b/src/malli/registry.cljc
@@ -14,19 +14,11 @@
     (-schema [_ type] (schemas type))
     (-schemas [_] schemas)))
 
-(defn registry
-  [?registry]
-  #?(:clj
-     (when ?registry
-       (if (instance? malli.registry.Registry ?registry)
-         ?registry
-         (if (map? ?registry)
-           (simple-registry ?registry)
-           (when (satisfies? Registry ?registry)
-             ?registry))))
-     :cljs
-     (cond (satisfies? Registry ?registry) ?registry
-           (map? ?registry) (simple-registry ?registry))))
+(defn registry [?registry]
+  (cond (nil? ?registry) nil
+        #?@(:clj [(instance? malli.registry.Registry ?registry) ?registry])
+        (map? ?registry) (simple-registry ?registry)
+        (satisfies? Registry ?registry) ?registry))
 
 ;;
 ;; custom

From 3e3e14cff40834614c10179fabc462230765c53c Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 09:16:07 +0300
Subject: [PATCH 07/11] tighten

---
 src/malli/core.cljc | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 99aa41402..a956b1e43 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -261,10 +261,7 @@
 (defn -registry
   {:arglists '([] [{:keys [registry]}])}
   ([] default-registry)
-  ([opts]
-   (or (when opts
-         (mr/registry (opts :registry)))
-       default-registry)))
+  ([opts] (or (when opts (mr/registry (opts :registry))) default-registry)))
 
 (defn- -lookup [?schema options]
   (let [registry (-registry options)]

From d9128ef3d241bafbda097268b9d70a522d2a9f39 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 12:29:12 +0300
Subject: [PATCH 08/11] partial cherry-pick from #521

---
 src/malli/core.cljc | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index a956b1e43..db2df1524 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -246,11 +246,6 @@
         child-transformer (if (seq child-transformers) (apply -comp (rseq child-transformers)))]
     (-intercepting parent-transformer child-transformer)))
 
-(defn- -properties-and-children [[x :as xs]]
-  (if (or (nil? x) (map? x))
-    [x (rest xs)]
-    [nil xs]))
-
 (defn- -register-var [registry v]
   (let [name (-> v meta :name)
         schema (-simple-schema {:type name, :pred @v})]
@@ -475,8 +470,8 @@
     (-children-schema [_ _])
     (-into-schema [parent properties children options]
       (-check-children! :or properties children {:min 1})
-      (let [children (mapv #(schema % options) children)
-            form (-create-form :or properties (map -form children))
+      (let [children (map #(schema % options) children)
+            form (delay (-create-form :or properties (map -form children)))
             ->parser (fn [f] (let [parsers (mapv f children)]
                                #(reduce (fn [_ parser] (miu/-map-valid reduced (parser %))) ::invalid parsers)))]
         ^{:type ::schema}
@@ -521,7 +516,7 @@
           (-options [_] options)
           (-children [_] children)
           (-parent [_] parent)
-          (-form [_] form)
+          (-form [_] @form)
           LensSchema
           (-keep [_])
           (-get [_ key default] (get children key default))
@@ -1577,8 +1572,11 @@
   ([type properties children]
    (into-schema type properties children nil))
   ([type properties children options]
-   (let [[properties options] (-properties-and-options properties options -form)]
-     (-into-schema (-schema type options) (if (seq properties) properties) children options))))
+   (let [properties (when properties (when (pos? (count properties)) properties))
+         r (when properties (properties :registry))
+         options (if r (-update options :registry #(mr/composite-registry r (or % (-registry options)))) options)
+         properties (if r (assoc properties :registry (-property-registry r options -form)) properties)]
+     (-into-schema (-schema type options) properties children options))))
 
 (defn type
   "Returns the Schema type."
@@ -1633,8 +1631,14 @@
    (cond
      (schema? ?schema) ?schema
      (into-schema? ?schema) (-into-schema ?schema nil nil options)
-     (vector? ?schema) (let [[p c] (-properties-and-children (rest ?schema))]
-                         (into-schema (-schema (first ?schema) options) p c options))
+     (vector? ?schema) (let [t (nth ?schema 0)
+                             n (count ?schema)
+                             ?p (when (> n 1) (nth ?schema 1))]
+                         (if-let [p (when (or (nil? ?p) (map? ?p)) ?p)]
+                           (let [c (when (< 2 n) (subvec ?schema 2 n))]
+                             (into-schema (-schema t options) p c options))
+                           (let [c (when (< 1 n) (subvec ?schema 1 n))]
+                             (into-schema (-schema t options) nil c options))))
      :else (if-let [?schema' (and (-reference? ?schema) (-lookup ?schema options))]
              (-pointer ?schema (schema ?schema' options) options)
              (-> ?schema (-schema options) (schema options))))))

From c9f47985b6b1724841ec68e0ffdb1e3e83fe27c6 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 12:36:45 +0300
Subject: [PATCH 09/11] some numbers

---
 perf/malli/creation_perf_test.cljc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/perf/malli/creation_perf_test.cljc b/perf/malli/creation_perf_test.cljc
index a503386c7..30ae52829 100644
--- a/perf/malli/creation_perf_test.cljc
+++ b/perf/malli/creation_perf_test.cljc
@@ -86,11 +86,11 @@
   ;; schema creation
   ;;
 
-  ;; 480ns
+  ;; 480ns -> 400ns
   (bench (m/schema :int))
   (profile (m/schema :int))
 
-  ;; 44µs
+  ;; 44µs -> 31µs
   (bench (m/schema ?schema))
   (profile (m/schema ?schema)))
 
@@ -112,6 +112,7 @@
 
   ;; 51µs
   ;; 44µs (-set-children, -set-properties)
+  ;; 29µs (lot's of stuff)
   (bench (mu/closed-schema schema))
   (profile (mu/closed-schema schema)))
 

From 32068c650b9d658af39c001e085f84be9f19135f Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 13:11:02 +0300
Subject: [PATCH 10/11] fix

---
 perf/malli/creation_perf_test.cljc |  3 +++
 src/malli/core.cljc                | 13 ++++++-------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/perf/malli/creation_perf_test.cljc b/perf/malli/creation_perf_test.cljc
index 30ae52829..cb0eee9db 100644
--- a/perf/malli/creation_perf_test.cljc
+++ b/perf/malli/creation_perf_test.cljc
@@ -51,10 +51,13 @@
   ;;
 
   ;; 5.2µs
+  ;; 3.6µs
   (bench (m/validate [:or :int :string] 42))
   (profile (m/validate [:or :int :string] 42))
 
   ;; 3.0µs
+  ;; 500ns (delayed mapv childs)
+  ;; 1.7µs
   (bench (m/schema [:or :int :string]))
   (profile (m/schema [:or :int :string]))
 
diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index db2df1524..067565a3f 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -470,7 +470,7 @@
     (-children-schema [_ _])
     (-into-schema [parent properties children options]
       (-check-children! :or properties children {:min 1})
-      (let [children (map #(schema % options) children)
+      (let [children (mapv #(schema % options) children)
             form (delay (-create-form :or properties (map -form children)))
             ->parser (fn [f] (let [parsers (mapv f children)]
                                #(reduce (fn [_ parser] (miu/-map-valid reduced (parser %))) ::invalid parsers)))]
@@ -1633,12 +1633,11 @@
      (into-schema? ?schema) (-into-schema ?schema nil nil options)
      (vector? ?schema) (let [t (nth ?schema 0)
                              n (count ?schema)
-                             ?p (when (> n 1) (nth ?schema 1))]
-                         (if-let [p (when (or (nil? ?p) (map? ?p)) ?p)]
-                           (let [c (when (< 2 n) (subvec ?schema 2 n))]
-                             (into-schema (-schema t options) p c options))
-                           (let [c (when (< 1 n) (subvec ?schema 1 n))]
-                             (into-schema (-schema t options) nil c options))))
+                             ?p (when (> n 1) (nth ?schema 1))
+                             s (-schema t options)]
+                         (if (or (nil? ?p) (map? ?p))
+                           (into-schema s ?p (when (< 2 n) (subvec ?schema 2 n)) options)
+                           (into-schema s nil (when (< 1 n) (subvec ?schema 1 n)) options)))
      :else (if-let [?schema' (and (-reference? ?schema) (-lookup ?schema options))]
              (-pointer ?schema (schema ?schema' options) options)
              (-> ?schema (-schema options) (schema options))))))

From 2a242535560fab13d52527fbf86564e3d36fca74 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Mon, 23 Aug 2021 13:40:38 +0300
Subject: [PATCH 11/11] .

---
 src/malli/core.cljc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/malli/core.cljc b/src/malli/core.cljc
index 067565a3f..9114a3b5d 100644
--- a/src/malli/core.cljc
+++ b/src/malli/core.cljc
@@ -131,8 +131,8 @@
   (reduce-kv #(if (= (name prefix) (namespace %2)) (assoc %1 (keyword (name %2)) %3) %1) {} m))
 
 (defn -check-children! [type properties children opts]
-  (let [size (count children), min (or (:min opts) 0), max (or (:max opts) size)]
-    (when (or (< size min) (> size max))
+  (let [size (count children), min (:min opts), max (:max opts)]
+    (when (or (and min (< size min)) (and max (> size max)))
       (-fail! ::child-error {:type type, :properties properties, :children children, :min min, :max max}))))
 
 (defn -create-form [type properties children]