diff --git a/TODO.md b/TODO.md
--- a/TODO.md
+++ b/TODO.md
@@ -14,9 +14,7 @@
 
 * parameterize number of tests in test programs and add slow-test target
 
-* add diff test for IO functions (diff w/ model output and exit status)
 
-
 documentation
 -------------
 
@@ -25,8 +23,8 @@
 * on data-invariant.md, write missing section;
 
 
-v0.6.7
-------
+other improvements
+------------------
 
 * On `bench/tiers`, print if the enumeration has repetitions
   (import `Function.Eq` for that)
@@ -43,6 +41,35 @@
     classifyBy :: (a -> b) -> [a] -> [(b,a)]
 	countsBy :: (a -> b) -> [a] -> [(b,Int)]
 
+* further improve showing of functions, indead of showing:
+
+    \p q -> case (p,q) of
+            (False,False) -> False
+            (False,True)  -> False
+            (True,False)  -> True
+            (True,True)   -> False
+
+  actually show just:
+
+    \p q -> case (p,q) of
+            (True,False)  -> True
+			_             -> False
+
+  Some thinking may have to be done for:
+
+    \x y -> case (x,y) of
+	        (0,0) -> 0
+			(0,1) -> 0
+			(1,1) -> 1
+			(1,0) -> 1
+			(0,2) -> 0
+			(1,1) -> 1
+			(2,0) -> 1
+			...
+
+  Where: `const (const 1) ->/ [(1,const 0)]`.
+
+
 * idea for restructuring Function modules (all under `Test.LeanCheck.Function`):
 
 	Show                  -- exports just Show (a -> b)
@@ -67,14 +94,10 @@
   a mixed strategy for generation of values.
 
 
-v0.6.8
-------
+later
+-----
 
 * implement stub `Test.LeanCheck.Function.*` modules;
-
-
-v0.6.9
-------
 
 * somehow, improve the improve the enumeration of `Char`s:
 
diff --git a/leancheck.cabal b/leancheck.cabal
--- a/leancheck.cabal
+++ b/leancheck.cabal
@@ -11,7 +11,7 @@
 -- this cabal file too complicated.  -- Rudy
 
 name:                leancheck
-version:             0.6.6
+version:             0.6.7
 synopsis:            Cholesterol-free property-based testing
 description:
   LeanCheck is a simple enumerative property-based testing library.
@@ -50,7 +50,7 @@
 source-repository this
   type:            git
   location:        https://github.com/rudymatela/leancheck
-  tag:             v0.6.6
+  tag:             v0.6.7
 
 library
   exposed-modules: Test.LeanCheck