Simplify the compiler, better subquery support

The compiler's been simplified a bit by breaking out the `writer` stuff into
its own namespace and by generally making the monadic stuff better. It's all
hidden behind a nice, simple, `clojure-sql.compiler/compile` function now. Call
that and you'll get back what you need. (Internally it's a writer monad which
is really modelled as a state monad with the only operation able to be
performed on the state being `tell`.)

Subqueries are now handled by the DSL in such a way as to not blow up
everything. Subqueries have no support for referencing values in the
superquery, though, so their utility is quite limited at present. Thinking
about how to do subqueries properly may be difficult.

1 files changed, 6 insertions, 13 deletions

diff --git a/src/clojure_sql/query.clj b/src/clojure_sql/query.clj
index 239aab4..00eb212 100644
--- a/src/clojure_sql/query.clj
+++ b/src/clojure_sql/query.clj
@@ -1,20 +1,13 @@
-(ns clojure-sql.query
-  (:require [clojure-sql.compiler :as c]))
+(ns clojure-sql.query)
 
-
-(def ^:private ^:dynamic *database-type* nil)
-(defn set-database-type! [new-type]
-  (alter-var-root #'*database-type* (constantly new-type))
-  nil)
-
-(def ^:private ^:dynamic *query-deref-behaviour* #(c/compile-query *database-type* %))
+(def ^:private ^:dynamic *query-deref-behaviour* identity)
 (defn set-query-deref-behaviour! [f]
   (alter-var-root #'*query-deref-behaviour* (constantly f))
   nil)
 
-(defrecord ^:private Query []
+(defrecord ^:private Query [] 
   clojure.lang.IDeref
   (deref [this] (*query-deref-behaviour* this)))
-(defmethod print-method Query [query writer]
-  (binding [*out* writer]
-    (pr (c/compile-query nil query))))
+
+(def query? (partial instance? (class (->Query))))
+