diff --git a/types.go b/types.go
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--- /dev/null
+++ b/types.go
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package main
+
+type Projection struct {
+	sample float32
+	stats  RecordStats
+}
+
+type Features map[string]float32
+
+type RecordStats struct {
+	compatibility float32
+	count         int
+}
+
+type Range struct {
+	max float32
+	min float32
+}
+
+type Record struct {
+	accessCount    int
+	compatibility  float32
+	distanceToStn  float32
+	distanceToUser float32
+	features       Features
+	id             int
+	name           string
+	score          float32
+}
+
+type Records []Record
+
+func (slice Records) Len() int {
+	return len(slice)
+}
+
+func (slice Records) Less(i, j int) bool {
+	return slice[i].score > slice[j].score
+}
+
+func (slice Records) Swap(i, j int) {
+	slice[i], slice[j] = slice[j], slice[i]
+}