diff --git a/src/opennlp/span.clj b/src/opennlp/span.clj
index c311f12..f7d9ce0 100644
--- a/src/opennlp/span.clj
+++ b/src/opennlp/span.clj
@@ -33,7 +33,8 @@
 (defn merge-spans
   "Given two overlapping spans where the first comes before the second, return a
   merged span with the type of the first."
-  [A B] (assoc A :end (:end B)))
+  [A B] 
+  (assoc A :end (:end B)))
 
 (defn span-disjoint?
   "Return true of A does not overlap B."
@@ -42,13 +43,14 @@
 
 (defn span-overlaps?
   "Return true if A overlaps B."
-  [A B] (not (span-disjoint? A B)))
+  [A B] 
+  (not (span-disjoint? A B)))
 
 (defn intersection-span
-  "Return the intersection of two spans as a span."
+  "Return the intersection of two spans as a span. Type of new span is :intersection."
   [A B]
   {:pre [(not (span-disjoint? A B))]}
-  (make-span (max (:start A) (:start B)) (min (:end A) (:end B)) nil))
+  (->Span (max (:start A) (:start B)) (min (:end A) (:end B)) :intersection))
 
 (defn span-length
   "Return the length of the span."
@@ -63,11 +65,10 @@
 (defn shift-span
   "Shift a span by i positions."
   [span i]
-  (make-span (+ (:start span) i) (+ (:end span) i) (:type span)))
+  (->Span (+ (:start span) i) (+ (:end span) i) (:type span)))
 
 (defn between-span
-  "Return a span of the area between two spans A and B. Precondition: (:end A)
-  < (:start B)."
+  "Return a span of the area between two spans A and B. Type of new span is :between."
   [a b]
-  {:pre [(< (:end a) (:start b))]}
-  (make-span (:end a) (:start b) :between))
+  {:pre [(<= (:end a) (:start b))]}
+  (->Span (:end a) (:start b) :between))