diff --git a/Data/Boolean.hs b/Data/Boolean.hs
--- a/Data/Boolean.hs
+++ b/Data/Boolean.hs
@@ -40,6 +40,7 @@
   | Boolean :&&: Boolean
   -- | and disjunction of boolean formulas.
   | Boolean :||: Boolean
+ deriving Show
 
 -- | Literals are variables that occur either positively or negatively.
 -- 
diff --git a/incremental-sat-solver.cabal b/incremental-sat-solver.cabal
--- a/incremental-sat-solver.cabal
+++ b/incremental-sat-solver.cabal
@@ -1,5 +1,5 @@
 Name:          incremental-sat-solver
-Version:       0.1.2
+Version:       0.1.3
 Cabal-Version: >= 1.6
 Synopsis:      Simple, Incremental SAT Solving as a Library
 Description:   This Haskell library provides an implementation of the