Proof-of-concept of a simple DSL for specifying servlets.

backend/bar-db.scm

@@ -29,20 +29,36 @@
     bar-db
     (
      bar-db-init!
+     bd-barcode-lookup
      )
 
   (import scheme
 	  (chicken base)
-	  postgresql)
+	  postgresql
+	  sql-null)
 
-  (define bar-db-conn (make-parameter #f))
+  (define bd-conn (make-parameter #f))
 
   (define (bar-db-init! name host user pass)
-    (bar-db-conn
+    (bd-conn
      (connect
       `((dbname . ,name)
 	(host . ,host)
 	(user . ,user)
 	(password . ,pass)))))
 
+  (define (sql-null->symbol v)
+    (if (sql-null? v)
+	'null
+	v))
+
+  (define (bd-barcode-lookup bc)
+    (sql-null->symbol
+     (car
+      (row-values
+       (query
+	(bd-conn)
+	"select sum(amount*case side when 'credit' then -1 else 1 end) amt from transaction_splits where account=$1"
+	bc)))))
+
   )