Added a fun Maybe example!

test_program.crf

@@ -1,31 +1,51 @@
+-- main = head (Cons (sum (repeat 10 5)) Nil);  
+
+main = case (bind (fmap (\s . s + 1) (Just 5)) (\s . pure (s + 10))) of {
+    Just a => a ;
+    Nothing => minusOne ;
+};
+
+---- MAYBE MONAD ----
+data Maybe () where {
+    Just : Int -> Maybe ()
+    Nothing : Maybe ()
+};
+
+fmap : (Int -> Int) -> Maybe () -> Maybe () ;
+fmap f m = case m of {
+    Just a => pure (f a) ;
+    Nothing => Nothing ;
+};
+
+pure : Int -> Maybe () ;
+pure x = Just x;
+
+-- scombinator not working yet :)
+
+bind : Maybe () -> (Int -> Maybe ()) -> Maybe () ;
+bind x f = case x of {
+    Just x => f x ;
+    Nothing => Nothing ;
+};
+
+-- represents minus one :)
+minusOne : Int ;
+minusOne = 9223372036854775807 + 9223372036854775807 + 1;
+{-
+---- LIST STUFF ----
 -- a simple list data type containing ints
 data List () where {
     Cons : Int -> List () -> List ()
     Nil  : List ()
 };
 
-main = head (repeat 10 5);  
-
-head : List () -> Int ;
-head x = case x of {
-    Cons h _ => h ;
-};
-
-repeat : Int -> Int -> List () ;
-repeat x n = case n of {
-    0 => Nil ;
-    n => Cons x (repeat x (n + minusOne)) ;
-};
-
-minusOne : Int ;
-minusOne = 9223372036854775807 + 9223372036854775807 + 1;
-
 -- take the length of a list
 length : List () -> Int ;
 length x = case x of {
     Cons _ xs => 1 + length xs ;
     Nil => 0 ;
 };
+
 -- sum a list
 sum : List () -> Int ; 
 sum x = case x of {
@@ -35,4 +55,18 @@ sum x = case x of {
 
 -- sum + length of a list
 sumlength: List () -> Int ;
-sumlength x = sum x + length x ;
+sumlength x = sum x + length x ;
+
+-- take the head of a list
+head : List () -> Int ;
+head x = case x of {
+    Cons h _ => h ;
+};
+
+-- repeat an element n times
+repeat : Int -> Int -> List () ;
+repeat x n = case n of {
+    0 => Nil ;
+    n => Cons x (repeat x (n + minusOne)) ;
+};
+-}