diff --git a/Makefile b/Makefile
index 9c0be2f..d5c908c 100644
--- a/Makefile
+++ b/Makefile
@@ -28,6 +28,9 @@ test :
 	./language ./sample-programs/basic-3
 	./language ./sample-programs/basic-4
 	./language ./sample-programs/basic-5
+	./language ./sample-programs/basic-6
+	./language ./sample-programs/basic-7
+	./language ./sample-programs/basic-8
 
 run :
 	cabal -v0 new-run language -- "test_program"
diff --git a/sample-programs/basic-5 b/sample-programs/basic-5
index 9a9a723..319b9b0 100644
--- a/sample-programs/basic-5
+++ b/sample-programs/basic-5
@@ -1,8 +1,8 @@
--- double : _Int -> _Int ;
--- double n = n + n;
+double : _Int -> _Int ;
+double n = n + n;
 
 id : 'a -> 'a ;
 id x = x ;
 
-main : ('a -> 'b -> 'c) ;
-main = id ;
+main : _Int ;
+main = id double 5;
diff --git a/sample-programs/basic-6 b/sample-programs/basic-6
new file mode 100644
index 0000000..467d263
--- /dev/null
+++ b/sample-programs/basic-6
@@ -0,0 +1,10 @@
+data Bool () where {
+    True : Bool ()
+    False : Bool ()
+};
+
+main : Bool () -> _Int ;
+main b = case b of {
+    False => 0;
+    True => 0
+}
diff --git a/sample-programs/basic-7 b/sample-programs/basic-7
new file mode 100644
index 0000000..3ddf98b
--- /dev/null
+++ b/sample-programs/basic-7
@@ -0,0 +1,10 @@
+data Bool () where {
+    True : Bool ()
+    False : Bool ()
+};
+
+ifThenElse : Bool () -> 'a -> 'a -> 'a;
+ifThenElse b if else = case b of {
+        True => if;
+        False => else
+    }
diff --git a/sample-programs/basic-8 b/sample-programs/basic-8
new file mode 100644
index 0000000..d916d03
--- /dev/null
+++ b/sample-programs/basic-8
@@ -0,0 +1,24 @@
+data Maybe ('a) where {
+    Nothing : Maybe ('a)
+    Just : 'a -> Maybe ('a)
+};
+
+fromJust : Maybe ('a) -> 'a ;
+fromJust a =
+    case a of {
+        Just a => a
+    };
+
+fromMaybe : 'a -> Maybe ('a) -> 'a ;
+fromMaybe a b =
+    case b of {
+        Just a => a;
+        Nothing => a
+    };
+
+maybe : 'b -> ('a -> 'b) -> Maybe ('a) -> 'b;
+maybe b f ma =
+    case ma of {
+        Just a => f a;
+        Nothing => b
+    }
diff --git a/test_program b/test_program
index bc463fe..d916d03 100644
--- a/test_program
+++ b/test_program
@@ -1,23 +1,24 @@
--- data Bool () where {
---     True : Bool ()
---     False : Bool ()
--- };
-
 data Maybe ('a) where {
     Nothing : Maybe ('a)
     Just : 'a -> Maybe ('a)
 };
 
--- main : Bool () -> Maybe (Bool ()) ;
--- main x =
---     case x of {
---         True => Nothing;
---         False => Just True
---     };
-
-fun : Maybe ('a) -> 'a ;
-fun a =
+fromJust : Maybe ('a) -> 'a ;
+fromJust a =
     case a of {
-        Just c => c
+        Just a => a
     };
 
+fromMaybe : 'a -> Maybe ('a) -> 'a ;
+fromMaybe a b =
+    case b of {
+        Just a => a;
+        Nothing => a
+    };
+
+maybe : 'b -> ('a -> 'b) -> Maybe ('a) -> 'b;
+maybe b f ma =
+    case ma of {
+        Just a => f a;
+        Nothing => b
+    }