prevent records from being treated as maps

Thanks to @djwhitt and @blinsay for reporting and for providing
test cases.

Fixes #106

src/honeysql/helpers.clj

@@ -7,12 +7,17 @@
 (defmethod build-clause :default [_ m & args]
   m)
 
+(defn plain-map? [m]
+  (and
+    (map? m)
+    (not (instance? clojure.lang.IRecord m))))
+
 (defmacro defhelper [helper arglist & more]
   (let [kw (keyword (name helper))]
     `(do
        (defmethod build-clause ~kw ~(into ['_] arglist) ~@more)
        (doto (defn ~helper [& args#]
-               (let [[m# args#] (if (map? (first args#))
+               (let [[m# args#] (if (plain-map? (first args#))
                                   [(first args#) (rest args#)]
                                   [{} args#])]
                  (build-clause ~kw m# args#)))

test/honeysql/core_test.clj

@@ -155,13 +155,13 @@
              :param3 param3})))))
 
 (deftest test-raw
-  (is (= ["1 + 1"]
+  (is (= ["SELECT 1 + 1 FROM foo"]
          (-> (select (sql/raw "1 + 1"))
              (from :foo)
              sql/format))))
 
 (deftest test-call
-  (is (= ["min(?)" "time"]
+  (is (= ["SELECT min(?) FROM ?" "time" "table"]
          (-> (select (sql/call :min "time"))
              (from "table")
              sql/format))))