diff --git a/src/datomish/db.cljc b/src/datomish/db.cljc
index 21859713..4f308092 100644
--- a/src/datomish/db.cljc
+++ b/src/datomish/db.cljc
@@ -144,13 +144,35 @@
           ]
       rowid)))
 
+
+(defn datoms-attribute-transform
+  [db x]
+  {:pre [(db? db)]}
+  (entid db x))
+
+(defn datoms-constant-transform
+  [db x]
+  {:pre [(db? db)]}
+  (sqlite-schema/->SQLite x))
+
+(defn datoms-source [db]
+  (source/map->DatomsSource
+    {:table :datoms
+     :fulltext-table :fulltext_values
+     :fulltext-view :all_datoms
+     :columns [:e :a :v :tx :added]
+     :attribute-transform (partial datoms-attribute-transform db)
+     :constant-transform (partial datoms-constant-transform db)
+     :table-alias source/gensym-table-alias
+     :make-constraints nil}))
+
 (defrecord DB [sqlite-connection schema entids ident-map current-tx]
   ;; ident-map maps between keyword idents and integer entids.  The set of idents and entids is
   ;; disjoint, so we represent both directions of the mapping in the same map for simplicity.  Also
   ;; for simplicity, we assume that an entid has at most one associated ident, and vice-versa.  See
   ;; http://docs.datomic.com/identity.html#idents.
   IDB
-  (query-context [db] (context/->Context (source/datoms-source db) nil nil))
+  (query-context [db] (context/->Context (datoms-source db) nil nil))
 
   (schema [db] (.-schema db))
 
diff --git a/src/datomish/query.cljc b/src/datomish/query.cljc
index ac7c13c3..2279c996 100644
--- a/src/datomish/query.cljc
+++ b/src/datomish/query.cljc
@@ -116,17 +116,18 @@
   [q]
   (dp/parse-query q))
 
-(comment
-  (def sql-quoting-style nil)
-  (datomish.query/find->sql-string
-    (datomish.query.context/->Context (datomish.query.source/datoms-source nil) nil nil)
-    (datomish.query/parse
-      '[:find ?timestampMicros ?page :in $ ?latest :where
-        [?page :page/starred true ?t]
-        [?t :db/txInstant ?timestampMicros]
-        (not [(> ?t ?latest)]) ])
-    {:latest 5})
-)
+#_
+(def sql-quoting-style nil)
+
+#_
+(datomish.query/find->sql-string
+  (datomish.query.context/->Context (datomish.query.source/datoms-source nil) nil nil)
+  (datomish.query/parse
+    '[:find ?timestampMicros ?page :in $ ?latest :where
+      [?page :page/starred true ?t]
+      [?t :db/txInstant ?timestampMicros]
+      (not [(> ?t ?latest)]) ])
+  {:latest 5})
 
 #_
 (datomish.query/find->sql-string
diff --git a/src/datomish/query/clauses.cljc b/src/datomish/query/clauses.cljc
index 69920f41..26d55dee 100644
--- a/src/datomish/query/clauses.cljc
+++ b/src/datomish/query/clauses.cljc
@@ -4,46 +4,46 @@
 
 (ns datomish.query.clauses
   (:require
-     [datomish.query.cc :as cc]
-     [datomish.query.functions :as functions]
-     [datomish.query.source
-      :refer [attribute-in-source
-              constant-in-source
-              source->from
-              source->constraints]]
-     [datomish.util :as util #?(:cljs :refer-macros :clj :refer) [raise raise-str cond-let]]
-     [datascript.parser :as dp
-      #?@(:cljs
-            [:refer
-             [
-              Constant
-              DefaultSrc
-              Function
-              Not
-              Or
-              Pattern
-              Placeholder
-              PlainSymbol
-              Predicate
-              Variable
-              ]])]
-     [honeysql.core :as sql]
-     [clojure.string :as str]
-     )
+   [datomish.query.cc :as cc]
+   [datomish.query.functions :as functions]
+   [datomish.query.source
+    :refer [attribute-in-source
+            constant-in-source
+            source->from
+            source->constraints]]
+   [datomish.util :as util #?(:cljs :refer-macros :clj :refer) [raise raise-str cond-let]]
+   [datascript.parser :as dp
+    #?@(:cljs
+        [:refer
+         [
+          Constant
+          DefaultSrc
+          Function
+          Not
+          Or
+          Pattern
+          Placeholder
+          PlainSymbol
+          Predicate
+          Variable
+          ]])]
+   [honeysql.core :as sql]
+   [clojure.string :as str]
+   )
   #?(:clj
-       (:import
-          [datascript.parser
-           Constant
-           DefaultSrc
-           Function
-           Not
-           Or
-           Pattern
-           Placeholder
-           PlainSymbol
-           Predicate
-           Variable
-           ])))
+     (:import
+      [datascript.parser
+       Constant
+       DefaultSrc
+       Function
+       Not
+       Or
+       Pattern
+       Placeholder
+       PlainSymbol
+       Predicate
+       Variable
+       ])))
 
 ;; Pattern building is recursive, so we need forward declarations.
 (declare
@@ -114,7 +114,7 @@
 (defn- plain-symbol->sql-predicate-symbol [fn]
   (when-not (instance? PlainSymbol fn)
     (raise-str "Predicate functions must be named by plain symbols." fn))
-  (#{:> :< :=} (keyword (name (:symbol fn)))))
+  (#{:> :>= :< :<= := :!=} (keyword (name (:symbol fn)))))
 
 (defn apply-predicate-clause [cc predicate]
   (when-not (instance? Predicate predicate)
@@ -240,14 +240,14 @@
 
 (defn not-join->where-fragment [not-join]
   [:not
-    (if (empty? (:bindings (:cc not-join)))
-      ;; If the `not` doesn't establish any bindings, it means it only contains
-      ;; expressions that constrain variables established outside itself.
-      ;; We can just return an expression.
-      (cons :and (:wheres (:cc not-join)))
+   (if (empty? (:bindings (:cc not-join)))
+     ;; If the `not` doesn't establish any bindings, it means it only contains
+     ;; expressions that constrain variables established outside itself.
+     ;; We can just return an expression.
+     (cons :and (:wheres (:cc not-join)))
 
-      ;; If it does establish bindings, then it has to be a subquery.
-      [:exists (merge {:select [1]} (cc->partial-subquery (:cc not-join)))])])
+     ;; If it does establish bindings, then it has to be a subquery.
+     [:exists (merge {:select [1]} (cc->partial-subquery (:cc not-join)))])])
 
 
 ;; A simple Or clause is one in which each branch can be evaluated against
diff --git a/src/datomish/query/source.cljc b/src/datomish/query/source.cljc
index 5c72612b..4a054e53 100644
--- a/src/datomish/query/source.cljc
+++ b/src/datomish/query/source.cljc
@@ -4,14 +4,14 @@
 
 (ns datomish.query.source
   (:require
-     [datomish.query.transforms :as transforms]
-     [datascript.parser
-      #?@(:cljs
-            [:refer [Variable Constant Placeholder]])])
+   [datomish.query.transforms :as transforms]
+   [datascript.parser
+    #?@(:cljs
+        [:refer [Variable Constant Placeholder]])])
   #?(:clj
-       (:import [datascript.parser Variable Constant Placeholder])))
+     (:import [datascript.parser Variable Constant Placeholder])))
 
-(defn- gensym-table-alias [table]
+(defn gensym-table-alias [table]
   (gensym (name table)))
 
 ;;;
@@ -43,25 +43,25 @@
   (constant-in-source [source constant]))
 
 (defrecord
-  DatomsSource
-  [table               ; Typically :datoms.
-   fulltext-table      ; Typically :fulltext_values
-   fulltext-view       ; Typically :all_datoms
-   columns             ; e.g., [:e :a :v :tx]
+    DatomsSource
+    [table               ; Typically :datoms.
+     fulltext-table      ; Typically :fulltext_values
+     fulltext-view       ; Typically :all_datoms
+     columns             ; e.g., [:e :a :v :tx]
 
-   ;; `attribute-transform` is a function from attribute to constant value. Used to
-   ;; turn, e.g., :p/attribute into an interned integer.
-   ;; `constant-transform` is a function from constant value to constant value. Used to
-   ;; turn, e.g., the literal 'true' into 1.
-   attribute-transform
-   constant-transform
+     ;; `attribute-transform` is a function from attribute to constant value. Used to
+     ;; turn, e.g., :p/attribute into an interned integer.
+     ;; `constant-transform` is a function from constant value to constant value. Used to
+     ;; turn, e.g., the literal 'true' into 1.
+     attribute-transform
+     constant-transform
 
-   ;; `table-alias` is a function from table to alias, e.g., :datoms => :datoms1234.
-   table-alias
+     ;; `table-alias` is a function from table to alias, e.g., :datoms => :datoms1234.
+     table-alias
 
-   ;; Not currently used.
-   make-constraints    ; ?fn [source alias] => [where-clauses]
-   ]
+     ;; Not currently used.
+     make-constraints    ; ?fn [source alias] => [where-clauses]
+     ]
   Source
 
   (source->from [source attribute]
@@ -93,15 +93,3 @@
 
   (constant-in-source [source constant]
     ((:constant-transform source) constant)))
-
-(defn datoms-source [db]
-  (map->DatomsSource
-    {:table :datoms
-     :fulltext-table :fulltext_values
-     :fulltext-view :all_datoms
-     :columns [:e :a :v :tx :added]
-     :attribute-transform transforms/attribute-transform-string
-     :constant-transform transforms/constant-transform-default
-     :table-alias gensym-table-alias
-     :make-constraints nil}))
-
diff --git a/test/datomish/api.cljc b/test/datomish/api.cljc
index 5669a2fa..d1155dd0 100644
--- a/test/datomish/api.cljc
+++ b/test/datomish/api.cljc
@@ -37,3 +37,5 @@
 (def entid db/entid)
 
 (def ident db/ident)
+
+(def <q db/<?q)
diff --git a/test/datomish/query_test.cljc b/test/datomish/query_test.cljc
new file mode 100644
index 00000000..df527f4d
--- /dev/null
+++ b/test/datomish/query_test.cljc
@@ -0,0 +1,54 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+(ns datomish.query-test
+  #?(:cljs
+     (:require-macros
+      [datomish.pair-chan :refer [go-pair <?]]
+      [datomish.node-tempfile-macros :refer [with-tempfile]]
+      [cljs.core.async.macros :as a :refer [go]]))
+  (:require
+   [datomish.api :as d]
+   #?@(:clj [[datomish.pair-chan :refer [go-pair <?]]
+             [tempfile.core :refer [tempfile with-tempfile]]
+             [datomish.test-macros :refer [deftest-async]]
+             [clojure.test :as t :refer [is are deftest testing]]
+             [clojure.core.async :refer [go <! >!]]])
+   #?@(:cljs [[datomish.pair-chan]
+              [datomish.test-macros :refer-macros [deftest-async]]
+              [datomish.node-tempfile :refer [tempfile]]
+              [cljs.test :as t :refer-macros [is are deftest testing async]]
+              [cljs.core.async :as a :refer [<! >!]]]))
+  #?(:clj
+     (:import [clojure.lang ExceptionInfo]))
+  #?(:clj
+     (:import [datascript.db DB])))
+
+#?(:cljs
+   (def Throwable js/Error))
+
+(def test-schema
+  [{:db/id        (d/id-literal :test -1)
+    :db/ident     :x
+    :db/unique    :db.unique/identity
+    :db/valueType :db.type/integer
+    :db.install/_attribute :db.part/db}
+   ])
+
+(deftest-async test-q
+  (with-tempfile [t (tempfile)]
+    (let [conn      (<? (d/<connect t))
+          {tx0 :tx} (<? (d/<transact! conn test-schema))]
+      (try
+        (let [{tx1 :tx} (<? (d/<transact! conn [{:db/id 101 :x 505}]))]
+
+          (is (= (<? (d/<q (d/db conn)
+                           `[:find ?e ?a ?v ?tx :in $ :where
+                             [?e ?a ?v ?tx]
+                             [(> ?tx ~tx0)]
+                             [(!= ?a ~(d/entid (d/db conn) :db/txInstant))] ;; TODO: map ident->entid for values.
+                             ] {}))
+                 [[101 (d/entid (d/db conn) :x) 505 tx1]]))) ;; TODO: map entid->ident on egress.
+        (finally
+          (<? (d/<close conn)))))))